Antihistamines in the management of canine atopic dermatitis: a retrospective study of 170 dogs (1992–1998)
G. ZUR, P. J. IHRKE, S. D. WHITE and P. H. KASS
School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot, Israel; School of Veterinary Medicine, University of California-Davis, Davis, California, USA
Antihistamines have become widely used in veterinary medicine for the treatment of atopic dermatitis during the past two decades. Antihistamines are used most commonly as an adjunct to other antipruritic therapies. Various antihistamines were given to 170 dogs diagnosed as having canine atopic dermatitis at the Veterinary Medical Teaching Hospital, University of California at Davis from 1992 to 1998. A good response to antihistamines was seen in 28% and a moderate response in 27% of the dogs. Diphenhydramine and hydroxyzine were the most commonly used and most often effective antihistamines, while chlorpheniramine and clemastine were administered less frequently and had much lower response rates. Dogs in which clinical signs occurred at younger ages exhibited better response to antihistamines (P = 0.008). Dogs that were 1–3 years of age when clinical signs of atopic dermatitis first occurred responded better to hydroxyzine than dogs that were less than 1 year of age when signs began (P = 0.052). Dogs that had signs for less than 1 year responded better to diphenhydramine (P = 0.027). Female dogs responded slightly better than male dogs to antihistamines in general (P = 0.076), but less well to diphenhydramine (P = 0.0362). Cocker spaniel dogs showed a tendency (P = 0.0653) not to respond to antihistamines. Dogs with positive reactions to weeds had very good response rates (P = 0.002). The efficacy of antihistamine treatment was not influenced by the severity of clinical signs.
Clinical trial of Cry j 1 DNA vaccine for hyposensitization in atopic dogs sensitized to Japanese cedar pollen
K. MASUDA, M. SAKAGUCHI, S. SAITO, K. YAMASHITA, K. OHNO, A. HASEGAWA and H. TSUJIMOTO
Department of Veterinary Internal Medicine, The University of Tokyo, Tokyo; National Institute of Infectious Diseases; The Jikei University School of Medicine; Pharmaceutical Research Laboratory, Hitachi Chemical, Chiba; Nihon University, Kanagawa, Japan
DNA vaccines are known to be quite effective in the alteration of immune responses. To investigate the usefulness of a DNA vaccine for hyposensitization in allergic diseases, a clinical trial using a DNA vaccine was used in atopic dogs sensitized to Japanese cedar (Cryptomeria japonica, CJ) pollen. Four atopic dogs with CJ pollinosis were found to be reactive to Cry j 1, one of the major allergens of CJ pollen, via intradermal skin testing, IgE serum antibody testing, and lymphocyte blastogenic response. These tests all indicated that Cry j 1 was the major allergen in these four atopic dogs. Three dogs were injected with Cry j 1 DNA vaccine, a plasmid containing Cry j 1 gene (pCACJ1), and one dog was injected with the plasmid without Cry j 1 gene insert (pCANC) as a negative control. The plasmids (0.5 mg head−1) were injected intramuscularly once monthly for 5 months. DNA vaccination finished just before the usual CJ pollen season (March to April). In 2/3 dogs injected with pCACJ1, clinical signs of atopic dermatitis were not seen, whereas the control dog developed typical atopic dermatitis. After DNA vaccination, lymphocyte blastogenic response to CJ pollen extract was found to decrease in the three treated dogs. These data suggest that Cry j 1 DNA vaccine can be a novel treatment to induce hyposensitization in atopic dogs sensitized to CJ pollen. Supported by a grant from the Science and Technology Agency in Japan.
Why do owners discontinue immunotherapy?
H. T. POWER
Dermatology for Animals, Campbell, California, USA
Most studies evaluating the efficacy of immunotherapy for the management of canine atopic dermatitis (CAD) have focused on patients actively receiving immunotherapy. The present study was performed to evaluate some of the reasons why owners discontinued immunotherapy. A questionnaire was mailed to 256 clients who had failed to reorder allergens within the last 18 months. A similar questionnaire was sent to 140 clients whose dogs were receiving immunotherapy. Of those patients that were no longer receiving immunotherapy, 23% showed no signs of CAD, 12% were partially improved and 64% still exhibited allergic symptoms. These clinical signs consisted of generalized pruritus (39%), pedal pruritus (31%), otitis (10%) and facial pruritus (6%). In dogs with persistent signs of CAD, therapeuticc management approaches included: steroid therapy (21%); antibiotic, antifungal and/or nonsteroidal antipruritic medication (29%); increased attention to shampoo therapy, flea control, and diet (27%); alternative veterinary therapies (4%); or ‘learning to live with it’ (14%). Owners who had discontinued immunotherapy reported to have done so because of persistence of clinical signs (44%), resolution of signs and lesions (29%), or clinical signs controlled with a combination of flea control, shampoo therapy and/or diet (13%). Of owners maintaining immunotherapy, 65% reported ‘good’ to ‘excellent’ control of their dog’s allergic signs. This study suggests that some dogs achieve resolution of signs of CAD with immunotherapy of limited duration. Additionally, these results imply that evaluations of the efficacy of immunotherapy should include patients in which immunotherapy is discontinued.
Quantification of indoor allergens from house-dust samples taken from the home environment of atopic dogs
I. Medical Clinic, Veterinary University, Vienna, Austria
The concentration of environmental allergens plays a role in the threshold phenomenon of atopic dermatitis. In several studies involving asthmatic people or people with atopic dermatitis, indoor allergens were quantified. Concentratoins greater than 2 μg g−1 dust were proposed as the threshold for risk of sensitization in people. The purpose of this study was to quantify the allergen concentrations in house-dust samples from homes where an atopic dog lived. Dogs suspected of being atopic based upon the history and clinical signs were either intradermally skin tested or had an in vitro serum test performed to confirm the diagnosis. Dust samples were collected from 100 homes where an atopic dog lived. The ‘Dustscreen® Test’ was performed to quantify the following allergen concentrations: house-dust mites (Der p 1 and 2, Der f 1 and 2), cat allergen (Fel d 1) and cockroach allergen (Bla g 2). In 3% of the samples taken from dog beds (n = 100) and in 2% of samples from the room (n = 100), the allergen Der p 1 was greater than 2 μg g−1 dust. Der f 1 was higher than 2 μg g−1 dust in 6% of the dog beds and in 5% of the rooms sampled. House-dust mite allergens of Group 2 (Der p 2 and Der f 2) were lower than 2 μg g−1 dust in all 200 samples. The cockroach allergen (Bla g 2) was negative in all 200 samples. In 1% of the samples from dog beds, the cat allergen concentration was higher than 2 μg g−1 dust. Supported by a grant from the ‘Hochschuljubiläumsstiftung’ of the city of Vienna.
Immunotherapy treatment in nine cats with feline asthma syndrome
Nine cats had respiratory signs of several months’ duration with a mean age of onset of 12 months of age. The clinical presentation included recurrent episodes of coughing, wheezing and dyspnoea. The episodes were severe and some required emergency treatment. All cats improved with glucocorticoid therapy and relapsed when the therapy was discontinued. The radiographic findings included prominent bronchial wall thickening and diffuse interstitial lung patterns. Increased numbers of inflammatory cells were found in all bronchial samples collected and the predominant cell types included eosinophils (>60%) and macrophages. These clinical findings were compatible with feline asthma syndrome. In order to find an underlying allergenic cause, intradermal skin testing was performed in all nine cats using 42 aeroallergens. The IDST were positive in the nine cats and the reactive allergens involved included Dermatophagoides farinae (four cats); Acarus siro (three cats); Glyciphagus domesticus, Dermatophagoides pteronyssinus, Tyrophagus putrescentiae, cockroach and ox-eye daisy (two cats), and false acacia (one cat). When storage mite or cockroach antigens were positive, removal of dried food was recommended and resulted in a remission of clinical signs for at least 2 years in two of the cats. Specific immunotherapy was prescribed for seven cats. Four cats have been followed since 1994, two cats since 1997 and one cat since 1998. Six cats improved considerably, allowing glucocorticoid therapy to be discontinued after 4–6 months. Immunotherapy has been continued.
The use of fluorescein for intradermal skin testing in cats
M. SCHENJKEL, B. BIGLER and T. JUNGI
Kleintierpraxis Laupeneck, Bern; and University of Bern, Bern, Switzerland
Intradermal skin testing (IDST) in atopic cats is a difficult diagnostic procedure. Most clinicians find feline IDSTs difficult to interpret. In this study, a technique is described that allows for better visualization of IDST reactions in cats. One hundred and eight cats with clinical signs compatible with possible atopic dermatitis were intradermally skin tested. Clinical signs included pruritus, symmetrical alopecia, miliary dermatitis and eosinophilic granuloma complex lesions. Twenty cats without signs of atopic dermatitis were tested using the same procedure (negative control group). Cats received intramuscular atropine and xylazine HCL for sedation. The lateral thorax was clipped and prepared for the intradermal injection of 29 different allergens. To better visualize the results of the test, fluorescein was administered intravenously just prior to the injection of the allergens. Due to extravasation of the fluorescein in an allergic skin reaction, positive reactions were seen as well demarcated fluorescent wheals under an ultraviolet (Wood’s) lamp. Seventy-five cats tested positive, while none of the negative control cats tested positive. The most common allergic reactions were to Dermatophagoides farinae, Dermatophagoidespteronyssinus, Acarus siro and Tyrophagus putrescientiae. The most common clinical presentation was abdominal alopecia with intensely pruritic lesions (miliary dermatitis and/or eosinophilic granuloma complex lesions). Immunotherapy was successful in 70% of the cats. This study was self-funded.
Intradermal skin testing in Icelandic horses
G. STARK and R. WAGNER
I. Medical Clinic for Horses and Small Animals, University for Veterinary Medicine of Vienna, Vienna, Austria
Intradermal skin testing is a valid diagnostic tool for the identification of allergens in horses with summer seasonal recurrent dermatitis (SSRD). In this study, commercial extracts of whole Culicoides variipennis, pollen, mites and insects were tested in Austrian SSRD Icelandic horses. Forty-three SSRD and 38 normal horses, vaccinated and regularly dewormed with ivermectin and without corticosteroid pretreament, were used in this study. Culicoidesvariipennis evoked positive cutaneous reaction in 1/38 normal horses and 3/43 SSRD horses at the proposed dilutions of 1:10 and 1:5. In normal horses, 22/38 and 13/43 SSRD horses showed positive responses at the dilution of 1:2. It is therefore concluded that the Culicoidesvariipennis extract is not appropriate to identify affected Icelandic horses in Austria. Reasons for this may be too low an allergen concentration per extract or the lack of cross-reactivity. No significant differences in skin reactions, either in number or intensity, to other allergens were detected in normal horses or horses with SSRD. Altogether 26/38 normal horses and 37/43 SSRD horses reacted to insects, 15/38 normal horses and 24/43 SSRD horses had cutaneous responses to insects and pollens and only one horse in each group reacted exclusively to house dust mite. No horse reacted to birch or Alternaria, whereas strong responses were seen with Dermatophagoides farinae (9/38 normal horses and 12/43 SSRD horses) and D. pteronyssinus (8/38 normal horses and 11/43 horses with CHS). Complete negative test results were visible in 11/38 normal horses and 5/43 SSRD horses.
Atopy and the Venn Diagram: explaining concepts to clients
C. J. CHESNEY
Mott Clinic for Veterinary Dermatology, Broadclyst, Exeter, UK
The diagnosis and long-term management of atopic patients is complicated for both clinicians and clients. It is often difficult for clients to grasp the relationship of concurrent skin diseases and/or flare factors. The purpose of this discussion is to present a Venn Diagram Model as a client education tool. The goal of this exercise was to find a visual aid to help clients understand the complexities of atopic dermatitis. Data for the construction of the Venn Diagram were obtained from case records in the author’s practice. The model depicts subsets of dogs with atopic dermatitis and staphylococcal pyoderma, food allergy, etc. A retrospective survey of client records for 12 months preceding and 12 months following introduction of the teaching model was carried out. The survey focused on client compliance and completion of food trials. The retrospective survey showed that the number of cases lost to follow-up after introduction of the Venn Diagram explanation was significantly less than that for the immediately preceding year (P = 0.0031), thus implying that the teaching tool has a positive impact. In the year preceding its use 39/75 (52%) of cases completed the trial compared with 59/82 (72%) after its introduction. This model enabled clients to grasp the factors involved in the pathogenesis of the signs affecting their dog. It may be a useful aid in explaining the intricacies of atopy. The model presents, in a readily accessible manner, an overview of several factors, the implied relationships between them, and their relative numerical importance.
Treatment of canine atopic dermatitis using anti-allergic peptides (MS-antigen) extracted from the urine of human patients with allergic diseases
N. YOSHIDA, F. NAITOH, K. IIMORI and T. IWASAKI
Veterinary Medical Teaching Hospital, Gifu University, Gifu, Japan
We describe the treatment of two dogs with atopic dermatitis using nonspecific immunotherapy. Both dogs were treated with MS-antigen (Hitachi Chemical, Ibaraki, Japan); this drug has been shown to have an effective antiallergic mechanism in people. A 3-year-old male West Highland white terrier dog was presented with a 2-year history of severe nonseasonal pruritus, lichenification and pigmentation in the axillary, inguinal and pinnal regions. Prior conventional treatment resulted in little improvement. Intradermal skin testing showed positive reactions to house dust mites and mugwort. The dog received a total of 15 injections of MS-antigen. Therapy was started with a gradual increase from 0.2 mL up to 1.0 mL every 3–4 days. Thereafter, the dog received 1.0 mL once monthly for 6 months. There was a marked improvement in clinical signs by the 12th injection or after 5 months of treatment. The second patient was a 5-year-old male black Labrador retriever dog with persistent scaling, erythema and severe pruritus. Intradermal skin testing revealed positive reactions to almost all commonly tested allergens, including house dust mites, pollens, weeds, foods, fleas, and dander. MS-antigen therapy was started as described above. After the 15th injection, the dog’s scaling and pruritus had resolved. After 20 injections, the dog’s clinical response allowed for the withdrawl of other therapeutic agents. MS-antigen may serve as an alternative to antigen-specific immunotherapy in canine atopic dermatitis. This work was supported by a Grant-in-Aid from the Ministry of Education, Science, Sports and Culture (#10839007).
A comparative study of the Heska Allercept® test and intradermal skin testing in dogs with suspected atopic dermatitis in the UK
A. P. FOSTER, J. D. LITTLEWOOD, P. WEBB, J. L. N. WOOD, K. ROGERS and S.E. SHAW
Department of Clinical Veterinary Science, University of Bristol, Langford; Animal Health Trust, Newmarket, UK
Atopic dermatitis in dogs is a common allergic skin disease that affects substantial numbers of dogs in the UK. The purpose of this study was to compare the results of allergy tests using intradermal skin tests and an in vitro test. In this study, 265 cases were evaluated. Dogs were intradermally skin tested with Greer™ allergens using a standard established technique. At the same time, serum samples were drawn and submitted for evaluation by ELISA using the Allercept® test for allergen-specific IgE. The allergens used in the in vitro and intradermal skin test included grass, tree and weed pollens, molds, flea saliva and house dust mite species. The optical density readings from the ELISA for each allergen were compared with the results of IDST for the 265 dogs. The prevalence of positive reactions in the ELISA was equal or greater for almost all of the allergens, except for two notable exceptions, Dermatophagoides farinae and D. pteronyssinus. These two allergens were the most common positive reactions by IDST (prevalence, D. farinae = 78.9%, D. pteronyssinus = 66.4%). The results of the two tests were significantly different (McNemar’s test, P < 0.05) for 16 of the 22 allergens. The sensitivities of the ELISA compared to the skin tests (where there were more than three dogs with positive reactions in both tests) varied between 19.3% and 77.1% (D. pteronyssinus = 19.3%, D. farinae = 67.9%) and the specificity varied between 64.2% and 96.6% (D. pteronyssinus = 96.6%, D. farinae = 89.3%).
Acitretin for the treatment of primary seborrhoea in Cocker spaniel dogs
Charles Small Animal Clinic, Taipei, Taiwan, Republic of China
Acitretin (Neotigason®, Soriatane®Roche) is a synthetic retinoid. This is a new drug for the treatment of disorders of keratinization. In this study, acitretin was used to treat six Cocker spaniel dogs diagnosed with primary seborrhoea. The purpose of this clinical trial was to evaluate the therapeutic benefit of this drug and note any adverse effects or safety concerns associated with its use. Dogs were treated for 6 weeks at a dosage of 10 mg per dog or approximately 1–1.42 mg kg−1. At the end of 6 weeks, the owners reported a clinical improvement in skin lesions. In addition, improvements were also found in dermatopathological changes within these 6 weeks of therapy. According to the manufacturer, possible adverse effects include heptotoxicity, keratoconjunctivitis sicca, triglyceride elevation and musculoskeletal ab-normalities. No adverse effects were noted in these six dogs. Supported by a grant from The Association of Veterinary Dermatology-Taipei and Roche Products Ltd, Taiwan.
Clinical and histopathological course, management and heredity of sebaceous adenitis in the Akita dog
I. M. REICHLER, B. HAUSER, I. SCHILLER, M. HUBLER, R. W. DUNSTAN, K. M. CREDILLE, H. BINDER, T. GLAUSE and S. ARNOLD
Faculty of Veterinary Medicine, University of Zürich, Switzerland; College of Veterinary Medicine, Texas A & M University, College Station, Texas, USA
The Akita dog breed has a high predisposition for sebaceous adenitis. This study describes the clinical and histopathological findings in 26 Akita dogs with sebaceous adenitis confirmed by skin biopsy. The histological findings showed an inflammatory reaction targeted against the sebaceous glands, or a reduction in the number of glands. The first skin lesions occurred mainly on the dorsal midline. Clinically, they appeared as small areas of scaling and alopecia and over time lesions became generalized. Not all dogs went on to develop generalized skin lesions, in some dogs lesions improved. Progressive sebaceous gland destruction was variable from dog to dog and was not seen in all cases. Bud-like sebaceous gland proliferation was seen, suggesting that regeneration of the sebaceous glands may occur. The variable clinical courses may be a reflection of different treatments. It is difficult to comment on the success of any one-treatment protocol, because of the small number of dogs, the wide variability in treatments and the differences in the clinical appearance of lesions. The owners were advised to bathe dogs 1–2 times per week using an antiseborrheic shampoo and moisturizing rinse. A long-term improvement was seen in six dogs that also received fish oil. By analysing the pedigrees of 16 litters an autosomal recessive pattern of inheritance seems most likely. Apart from a genetic predisposition, an immune mediated factor may also influence the onset and the course of sebaceous adenitis.
Effects of four diets with varying omega 6:omega 3 ratios on the health and appearance of the skin and hair coat in normal dogs
K. L. CAMPBELL, D. P. LAFLAMME and J. HARRISON
College of Veterinary Medicine, University of Illinois, Urbana, Illinois; Ralston Purina Company, St.Louis, Missouri, USA
Many dietary supplements and ‘premium’ diets are marketed with claims of improving the health and appearance of the skin and hair coats of dogs; however, few have been objectively evaluated. The objectives of this study were to compare the effects of four diets with varying ratios of omega 6:omega 3 fatty acids on the health of the skin and hair coat in normal dogs. Forty-eight healthy dogs were randomly assigned to one of four test diets via Latin squares (diets A, B, C, and D). The study was double-blinded. Dermatological assessments were done at the start and end of each feeding period and consisted of scoring hair shine, skin surface appearance, skin surface scaliness, ease of epilation of hairs, transepidermal water loss (Acaderm Tewameter, Menlo Park, CA), skin surface hydration (Acaderm Corneometer), skin surface lipid concentration (Acaderm Sebumeter), hair surface lipid concentration (Acaderm Sebumeter), and skin surface pH (Acaderm Skin pH Meter). Analysis of variance model for crossover design was used to assess diet effects while adjusting for variation among dogs. There were no significant differences attributable to the diets despite differences in omega 6:omega 3 ratios (24:1 for diet A, less than 1:1 for diet B, 5:1 for diet C, and 11:1 for diet D). This study shows that widely different ranges of omega 6:omega 3 ratios in nutritionally balanced diets have no apparent effects on the health of the skin and hair coat of healthy dogs. Supported by a grant from the Ralston Purina Company.
Four cases of canine metabolic epidermal necrosis
E. FLORANT, J. GUILLOT, F. DEGORCE-RUBIALES and M. MIALOT
Les Sablons Veterinary Clinic, Plaisir; Ecole Nationale Vétérinaire d’Alfort, Maisons-Alfort; Laboratoire d’Anatomie Pathologique Vétérinaire du Sud-Ouest, Toulouse; Laboratoire d’Histocytopathologie Vétérinaire, Maisons-Alfort, France
Four dogs (two male, two female) ranging in age from 7 to 10 years old were presented for examination. All of the dogs had a history of thick and adherent crusts and erosive to ulcerative skin lesions. The lesions were painful and developed on the pressure points, distal limbs, foot-pads (four dogs), lips, eyelids, anus, prepuce, vulva (two dogs) and scrotum (one dog). Secondary bacterial (four dogs) and Malassezia (two dogs) infections were present. Approximately 1–4 months after initial examination, clinical signs of systemic disease were observed. Two dogs developed gastrointestinal signs (diarrhoea, vomiting) and had elevated liver enzymes on serum biochemistry profiles. Histological examinations of skin biopsies were compatible with hepatocutaneous syndrome. Zinc, fatty acids and egg yolk supplementation led to a partial remission of skin lesions in two dogs. However, because of general debilitation all four dogs were euthanazed 2–9 months after diagnosis. Necropsy revealed cirrhosis of the liver in two dogs. No macroscopic or microscopic abnormalities were found on the liver or the pancreas in the two other dogs. These two dogs had normal serum chemistry profiles, but severe gastrointestinal signs before euthanasia. This report found that metabolic epidermal necrosis may not always be associated with hepatic or pancreatic lesions. In humans, the hepatocutaneous syndrome may be seen in association with such intestinal disorders as adenocarcinomas or Crohn’s disease. These case reports suggest that the same could be true in dogs; the hepatocutaneous syndrome may simply be a cutaneous reaction pattern to various metabolic abnormalities.
Response of adrenal sex hormones to cosyntropin in dogs with hyperadrenocorticism
L. A. FRANK, L. P. SCHMEITZEL and J. W. OLIVER
College of Veterinary Medicine, University of Tennessee, Knoxville, Tennessee, USA
Elevated concentrations of adrenal androgens poststimulation with cosyntropin (ACTH) are used to diagnose alopecic disorders in dogs presumably attributed to adrenal androgen imbalance. Canine hyperadrenocorticism may also be associated with a similar clinical appearance. Some clinicians measure adrenal androgen concentrations based on clinical appearance without first ruling out hyperadrenocorticism. The purpose of this study was to evaluate adrenal sex hormone concentrations in neutered dogs with hyperadrenocorticism. In a retrospective analysis, serum samples of 10 dogs diagnosed with hyperadrenocorticism were evaluated for cortisol, progesterone, testosterone, dehydroepiandrosterone sulphate (DHEAS) or androstenedione, and 17-OH progesterone before and 1 h after ACTH administration. Dogs with hyperadrenocorticism were selected based on clinical signs, clinicopathologic abnormalities, and an exaggerated ACTH stimulation test in most cases. Diagnosis was confirmed with a low dose dexamethasone suppression test (LDDST), ultrasonography, and/or response to treatment for hyperadrenocorticism. Eight of the dogs had substantial elevations in one or more of the adrenal sex hormones poststimulation (androstenedione, 5/9; progesterone, 6/10; 17-OH progesterone, 4/10; DHEAS, 2/8). Testosterone was not increased in any of the dogs tested. Only one dog failed to have any increases in adrenal sex hormones before or after ACTH stimulation. Results from this study support the importance of first ruling out hyperadrenocorticism before measuring adrenal sex hormone concentrations. The variability as to which adrenal sex hormone concentrations were elevated may indicate a role for these hormones in the many different clinical presentations seen with hyperadrenocorticism. Supported by the Department of Small Animal Clinical Sciences, University of Tennessee.
Seasonal variations in skin surface pH, skin surface hydration, and hair epilation of normal dogs in Midwestern United States climate
K. L. CAMPBELL, D. P. LAFLAMME and J. HARRISON
College of Veterinary Medicine, University of Illinois, Urbana, Illinois; Ralston Purina Company, St. Louis, Missouri, USA
Dog owners equate the appearance of the skin and hair coat with the health of their dog. Appearance is subjective; thus objective measurements are helpful in the evaluation of the effects of diets, supplements, and topical products on the skin and hair coat of dogs. Both subjective and objective measurements may be influenced by the season of the year. The goal of this study was to determine the effects of season on skin surface hydration, transepidermal water loss, skin surface scaliness, skin surface pH, skin surface lipid concentrations, and hair epilation of normal dogs in the Midwestern United States (Illinois). Forty-eight normal healthy dogs were included in the study and evaluated four times over a 1-year period. Analysis of variance and Tukey’s Honestly Significant Difference procedures were used to assess season differences in the above parameters. Significant seasonal differences were found for skin surface hydration (measured via Acaderm Corneometer, Menlo Park, CA), skin surface pH (measured via Acaderm Skin pH Meter, Menlo Park, CA), skin surface scaliness (visual scoring system), and ease of hair epilation (visual scoring system). Skin hydration was highest in the fall, skin pH was highest in the summer, skin scaliness was highest in the winter, and ease of hair epilation was highest in the spring. These results show that seasonal differences occur in both objective and subjective parameters used to assess the health of skin and hair coats in dogs. Supported by a grant from the Ralston Purina Company.
Cefadroxil in the treatment of canine pyoderma
F. SCARAMPELLA, C. NOLI and L. J. I. HORSPOOL
Viale dei Mille, Milan, Italy; Intervet International BV, Boxmeer, The Netherlands
The safety and efficacy of once daily administration of cefadroxil, a first generation cephalosporin, was compared with twice daily administration of amoxicillin–clavulanic acid, in the treatment of canine pyoderma in Germany, the Netherlands, the UK and Italy. Group 1 (104 dogs) was treated with cefadroxil (Cefa-cure®, Intervet) orally once daily at a dose rate of 20 mg kg−1 bodyweight. Group 2 (98 dogs) was treated with amoxicillin-clavulanic acid (Synulox® tablets, Pfizer) orally twice daily at a dose rate of 12.5 mg kg−1 bodyweight. Each dog was examined on days 0, 7 and 21, on the last day of treatment and again on days 7 and 28 post-cessation of therapy. Duration of treatment varied from 21 to 91 days. The clinical response to treatment was assessed using the change in the overall severity score, the proportion of treatment failures, and the overall response. Suspected adverse reactions to treatment (mild gastrointestinal signs) were reported for 3% of the dogs treated with cefadroxil and 1% of the dogs treated with amoxicillin-clavulanic acid. A similar reduction in the overall severity scores was observed in both groups. One week after treatment was stopped, 93% of Group 1 and 82% of Group 2 were classified as having responded to treatment. In the present study, cefadroxil produced a significantly better overall response than amoxicillin-clavulanic acid, a combination known to be effective in the treatment of canine pyoderma. Once daily administration of cefadroxil is a safe, effective and suitable treatment for canine pyoderma.
A dose response study to determine the optimal concentration of chlorhexidine in a shampoo base
K. V. MASON, A. FROST, D. O’BOYLE and L. MCKINNON
School of Veterinary Science, University of Queensland; Dermcare-Vet Pty Ltd, Springwood, Queensland, Australia
Chlorhexidine is a biguanidine antiseptic used at concentrations of up to 4% in shampoos for the treatment and prevention of pyoderma. There are conflicting results in studies on the efficacy of this common antiseptic in shampoos, due in part to differing concentrations of chlorhexidine in the shampoos. Currently there is no information on the optimal therapeutic concentration of chlorhexidine in a shampoo. This study describes the residual effectiveness of different chlorhexidine concentrations against Staphylococcus intermedius on dog skin. The varying concentrations were formulated in a pharmaceutically compatible shampoo base. Ten dogs had six areas of skin clipped and then randomly treated with 0%, 1%, 2%, 3%, or 4% chlorhexidine shampoo diluted 1:30. The shampoo was in contact with the skin for 10 min and then rinsed off with 400 mL of sterile water. After 24 h a standard cup made from the cut end of a 20 mL syringe was attached to each treatment site with methylmethacrylate glue. Each treatment site was then challenged with a broth solution containing 1×106S. intermedius using the cup device. The site was occluded using a sterile rubber stopper on the end of the syringe. After 5 h the number of viable colony forming units was calculated. Lecithin was added to the diluting medium to inactivate any residual chlorhexidine. The most effective concentrate was 3% (P < 0.01) followed by 4% (P < 0.05) with 2% having a slight but not significant effect and 1% having no effect. That finding that a 3% concentration was more effective than the 4% concentration is explained by an interaction of the excipient and the chlorhexidine, both of which are surfactants.
Comparison of two protocols of administration of cephalexin in the treatment of deep pyoderma in dogs
E. GUAGUÈRE, C. SALOMON and P. CADOT
Clinique Vétérinaire Saint Bernard, Lomme; Virbac S.A, Carros Cedex; Boulogne-Billancourt, France
Cephalexin and marbofloxacin are widely used in the treatment of canine pyoderma in Europe. A multicentre clinical trial was conducted to compare the efficacy of these two antibiotics in the treatment of canine deep pyoderma. The study was controlled and the patients were randomly assigned to treatment groups. A total of 98 dogs ranging in age from 9 months to 18 years were used in this study; 96 dogs finished the study. All dogs had a clinical diagnosis of deep pyoderma. Group C1 dogs (n = 28) were treated with cephalexin at a dose of 30 mg kg−1 orally once daily. Group C2 dogs (n = 33) were treated at the recommended dose of 15 mg kg−1 orally twice daily. Group M dogs were treated with marbofloxacin at a dose of 2 mg kg−1 orally once daily. Staphylococci were isolated in 51% of cases via culture and sensitivity; there were approximately 1.6 pathogen isolates per case. Deep pyoderma resolved in 75%, 85%, and 77% of dogs in Groups C1, C2, and M, respectively. Based upon the results of this study, we consider cephalexin at a dose of 30 mg kg−1 orally once daily to be effective in the treatment of canine deep pyoderma. Cephalexin is considered a time-dependent antibiotic in the treatment of staphylococcal infections and 15 mg kg−1 orally twice daily is the recommended dose. Nevertheless, cephalexin at a dose of 30 mg kg−1 orally once daily was very effective in this study. Several factors may explain this, including the extracellular concentration, as well as the post-antibiotic and subinhibitory effects of cephalexin.
Photodynamic therapy in veterinary dermatology: review and application
K. P. BYRNE and L. E. DUDA
School of Veterinary Medicine, University of Pennsylvania, Philadelphia, USA
Photodynamic therapy (PDT) uses a photosensitizer activated by light to induce cell death via formation of free radicals. Porphyrin derivatives have an affinity for tumour cells and their corresponding vasculature, making them photosensitive targets. The light source required depends on the sensitizer used and the type and location of the lesion. The most widely used lasers for PDT are the argon ion pumped dye laser (wavelength = 630 nm) and the gold vapor laser (628 nm). PDT has been used in cats and dogs with squamous cell carcinoma (SCC) and also has been used successfully in the treatment of Bowen’s disease in humans. A 17-year-old male-neutered domestic cat presented to the Veterinary Hospital University of Pennsylvania (VHUP) for evaluation of a pruritic skin lesion. A 4-cm crusted lesion was present on the ventral neck. Histological examination of a skin biopsy was diagnostic for SCC in situ. The lesion encompassed a significant portion of the neck, surgical excision was considered to be inadvisable and PDT was performed. Photofrin® (Sanofi Pharmaceuticals, New York, USA) 3.0 mg kg−1 was given intravenously. Forty-eight hours later, an application of laser light was performed using a potassium titanyl phosphate (KTP)/neodymium (ND):YAG switchable pump laser and PDT dye module tuned to a wavelength of 630 nm. Light was delivered at a fluence of 31.5 J cm−2 and a power density of 65 mW cm−2, and then a second application was delivered at a fluence of 43.5 J cm−2 and a power density of 100 mW cm−2. One year post-treatment the PDT treated area has no gross lesion compatible with SCC in situ.
Dermatitis and pythiosis in North Carolina horses following hurricane Floyd
S. L. VIVRETTE, J. L. BAKER, L. C. HUDSON, P. R. WOODS and L. J. KUHN
College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina; Southern Pines Equine Associates, Southern Pines, North Carolina; East Carolina Veterinary Service, Greenville, North Carolina, USA
Two dermatological problems were identified in horses in the state of North Carolina (NC) following hurricane Floyd in September 1999. Sixteen horses presented with diffuse dermatitis, scaling, crusting, variable erosions, and pitting oedema of the distal limbs. Lesions were generalized in one horse. Histological examination of skin biopsies showed there was mild to moderate diffuse neutrophilic and lymphocytic deep dermatitis and mild to moderate diffuse lymphocytic panniculitis with oedema. Bacterial cultures of skin biopsy specimens yielded numerous saprophytic microorganisms. Treatment included systemic administration of antibiotics in seven of the horses. Sloughing of skin of the distal extremities was observed in three of the treated horses that had been standing in heavily polluted water for 4 days. The skin lesions of all the horses resolved completely. The second problem included single to multiple, 20×20 cm proliferative, purulent, ulcerative lesions on the abdomen and thigh of three horses. Histological examination of skin biospy specimens showed there was abundant, pyogenic granulation tissue with marked eosinophilic inflammation. Poorly septate hyphae were present in the biopsy specimen of one horse. Pythium insidiosum was identified on culture of purulent material aspirated from lesions of two horses and serologically in three horses. Treatment, including systemic antimicrobials and topical therapy, was unsuccessful in two horses and they were euthanized. One horse had aggressive surgical resection of lesions, and 1-month post-surgery there was no evidence of recurrence. Pythiosis is rarely identified in NC horses. Both of these skin diseases were most likely due to horses standing in contaminated water for long periods of time.
Pasture dermatosis in the nonpigmented lower limb in the horse
M. M. SLOET VAN OLDRUITENBORGH-OOSTERBAAN, E. ENZERINK, J. P. KOEMAN and J. H. KNAAP
Faculty of Veterinary Medicine, Utrecht University; Research Institute for Horse Husbandry, Lelystad, The Netherlands
In the Netherlands, clinical symptoms of dermatitis, described as ‘leucocytoclastic pastern vasculitis’ by T. Stannard and as ‘photo-aggravated pastern vasculitis’ by S. White, are seen regularly. At a research farm, the condition occurs annually during the summer months. Only mares at pasture show lesions on the nonpigmented areas of the lower limbs and, in particular, the medial and lateral aspects of pastern and fetlock. Lesions are often multiple, reasonably well-demarcated, nonpruritic but painful. Sometimes, lesions are found on nonpigmented noses. Initially lesions are characterized by erythema and oozing accompanied by mild to severe oedema, after which crusting erosions and superficial ulcerations develop. In chronic cases, the lesions develop a rough ‘warty’ surface. It is rare in juvenile horses, and not seen in foals. In September 1997, 16 of 34 adult mares at the research farm showed lesions while at pasture. Skin biopsies from three mares with lesions revealed a slight perivascular oedema and perivascular lymphohistiocytic inflammation with a few neutrophils and eosinophils, in the upper dermis. A complete blood screen did not reveal abnormalities. Two mares with lesions were stabled and treated with prednisolone and seven were stabled only. The treated mares improved significantly and were better within 3 weeks, compared with the untreated horses. In 1998, 44 mares with nonpigmented lower limb(s) were divided into a paddock group (n = 10), kept in a sand-paddock and fed hay and concentrates, and a pasture group (n = 34), kept continuously at pasture. None of the paddock group developed lesions while 29 horses (85%) of the pasture group showed lesions of varying severity.
Linear ‘zebra’ urticarial dermatosis in multiple horses
H. C. SCHOTT II, E. J. ROSSER, P. BLOOM and J. VISSER
College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA
From 1995 to 1999, five geldings and one mare at a stable of 40 horses developed a linear ‘zebra’ dermatosis. Lesions were striking and consisted of parallel linear eruptions arising over the shoulders and extending caudodorsally to the flank. More subtle lesions were distributed in a curving dorsal to ventral pattern along the neck. Affected horses varied in breed and colour and ranged in age from 6 to 25 years. Although lesions tended to become more severe during the summer and fall, they never completely resolved. The condition was mildly pruritic as horses would occasionally bite at and/or rub the lesions. Horses were stabled at night (bedded on shavings) and turned out to pasture during the day. Feed consisted of locally grown hay and a grain mixture of oats and corn. Skin biopsies collected from one of the more severely affected horses revealed mild, superficial to mid-level, perivascular dermatitis composed of a mixture of mast cells, lymphocytes, and eosinophils. In addition, epidermal hyperplasia, dermal fibrosis, and eosinophilic necrotic crusts were apparent in traumatized areas. In the same horse, an intradermal skin test and an Onchocerca spp. macerated tissue preparation yielded negative results and a 30-day change in environment had no effect on the pattern or severity of lesions. Frequent treatment with ivermectin also had no apparent effect but the condition appeared to be partially responsive to systemic corticosteroid therapy. At present, the aetiology of this ‘zebra’ dermatosis remains an enigma, although an environmental trigger is suspected.
A multicentre prospective study of otitis externa in France: 802 cases
E. BENSIGNOR and D. LEGEAY
Veterinary Clinic, Paris and Schering-Plough Vétérinaire, Levallois-Perret, France
Canine otitis externa is a common problem and involves various predisposing, primary, and perpetuating causes. The purpose of this prospective study was to assess the epidemiological, clinical, and microbiological findings of canine otitis externa in France. Dogs with clinical signs of otitis externa (erythema of the ear canal and/or cerumen and/or pus and/or pain or pruritus) were entered into this study between late November and early December of 1999. The epidemiological, clinical, and microbial findings of each case were recorded. In addition, cases were classified as mite-related, erythematous-ceruminous or purulent. Bacterial cultures were done in cases of purulent otitis externa. There were 802 cases of otitis externa in this study. The mean age of the dogs was 5.9 years. Poodle dogs were predisposed (P < 0.05). Otitis externa was acute and chronic in 58% and 42% of the cases, respectively. Bilateral otitis was observed in 53% of the cases. Mite-related otitis was rare (7%). Non-parasite related erythematous-ceruminous otitis externa (72%) was more common than purulent otitis externa (21%). The main cause of erythematous-ceruminous otitis was infection with Malassezia pachydermatis (75%). In 70% of these cases, yeast was present in high numbers. Cocci were isolated in 82% of the cases, whereas rods were statistically less frequent (32%, P < 0.05). Bacteriological culture (112 samples) revealed that Staphylococcus intermedius, Pseudomonas aeruginosa and Proteus mirabilis were most the most common isolates from dogs with purulent otitis externa. Atopic dermatitis was a common underlying cause of otitis externa in dogs.
Efficacy of cyclosporin in the treatment of idiopathic sterile nondular panniculitis in two dogs
Clinique Vétérinaire Saint Bernard, Lomme, France
Idiopathic sterile nodular panniculitis (ISNP) refers to a sterile inflammatory disease of the subcutaneous fat. The aetiology is unknown and is most likely immunological. This disease usually responds well to glucocorticoids, but relapses are frequent requiring long-term alternate day therapy. This report describes the use of cyclosporin in two dogs with ISNP. An 8-year-old Gordon setter dog and a 5-year-old cross-bred daschshund dog were referred with the complaint of multiple, firm to fluctuant nodules on the trunk and in the subcutaneous tissue. Some of the nodules had ulcerated or fistulated and they exuded an oily, clear yellow liquid. The dogs were febrile. Bacterial cultures and an antinuclear antibody test were negative. Histological examination of biopsies showed a nodular to diffuse granulomatous panniculitis; microorganisms were not seen. The dogs were treated with cyclosporin at 5 mg kg−1 oraly once daily 2 h before meals. Within 2 weeks, there was an 80% reduction in the nodules and the dogs were afebrile. Treatment was continued for another 3 weeks; lesions were completely resolved by the end of 6 weeks of treatment. Cyclosporin was continued on an alternate day regimen for 1 month and then every 3 days for yet another month. No relapses were noted in the 6 months following the end of treatment. No adverse effects were noted. Cyclosporin was effective in the treatment of ISNP at dose of 5 mg kg−1. Response to cyclosporin therapy adds further evidence that the aetiology of ISNP may be immune-mediated.
Prevalence of Leishmania infection in dogs living in endemic regions
L. SOLANO-GALLEGO, P. MORELL, M. ARBOIX, J. ALBEROLA and L. FERRER
Universitat Autònoma de Barcelona, Barcelona; Centre Sanitari Municipal, Palma de Mallorca, Spain
There is increasing experimental and epidemiological evidence to suggest that the incidence of Leishmania infection dogs living in endemic countries is higher than described. In order to document this, we investigated the prevalence of Leishmania infantum infection in dogs living in Majorca (Spain), a Leishmania endemic area. Samples were collected from 100 dogs of varying ages and breeds that were euthanazed in an animal shelter operated by the city of Palma de Mallorca. All dogs were examined and the following diagnostic tests were performed: polymerase chain reaction (PCR) testing for Leishmania DNA in bone marrow aspirates and in skin and conjunctival biopsies; immunohistochemical staining for Leishmania organisms in skin and conjunctival biopsies; and detection of serum anti-Leishmania antibodies by enzyme-linked immunoassay. Leishmania organisms were detected, either by PCR or by immunohistochemistry, in 62 dogs. Parasites were most frequently detected in the skin (54 dogs). Of the infected animals, 30 dogs were seropositive and nine had clinical signs of canine leishmaniasis. In this study, we found that the infection rate was considerably higher than that detected by serology or by evidence of clinical disease. This fact must be taken into account in any programme or campaign designed to control canine and/or human leishmaniasis.
Comparison of polymerase chain reaction, parasitology and serology in the diagnosis of canine leishmaniosis
M. SARIDOMICHELAKIS, C. BILLINIS, M. MYLONAKIS, A. KOUTINAS, V. SPIROU, N. DIAKOU, D. ARGYRIADIS, L. LEONTIDES, A. GALATOS, P. GOULETSOU, M. LIAPI, C. PAITAKI, O. PAPADOPOULOS and S. HARALABIDIS
Clinic of Companion Animal Medicine, Laboratory of Microbiology and Infectious Diseases, Laboratory of Parasitology and Parasitic Diseases, Aristotles University of Thessaloniki; Center of Veterinary Institutes, Thessaloniki; Faculty of Veterinary Medicine, University of Thessaly, Karditsa, Greece
Polymerase chain reaction (PCR) in bone marrow (BM) samples, lymph node (LN) and BM parasitological examination, indirect immunofluorescence assay (IFA) and enzyme-linked immunosorbent assay (ELISA) are commonly used in the diagnosis of canine leishmaniosis (CL). The aim of this study was to compare the sensitivity and specificity of these methods between symptomatic and asymptomatic dogs. A total of 90 dogs were entered into the study. They were divided into three groups: Group A (n = 42) included symptomatic CL cases, Group B (n = 28) asymptomatically infected dogs and Group C (n = 20) noninfected dogs. The diagnosis was based on positive PCR and/or parasite detection in LN and/or BM aspiration smears. Dogs were considered uninfected when both PCR and parasitology were negative, even after examining 1000 oil fields. Because no single test was positive in Group C, the specificity of all five diagnostic tests was 100%. The sensitivity was 98.6% for PCR, 78.9% for LN parasitology, 65.7% for BM parasitology, 64.3% for IFA and 60.9% for ELISA when both Groups A and B were considered together. The relevant figures for Group A were 100% (PCR), 89.7% (LN), 90.2% (BM), 97.6% (IFA) and 95.1% (ELISA), whereas for Group B they were 96.4% (PCR), 55.6% (LN), 26.9% (BM), 14.3% (IFA) and 10.7% (ELISA). The sensitivity was significantly higher in Group A for LN (P < 0.01) and BM (P < 0.001) parasitology, as well as for the serological tests applied (P < 0.001), in comparison with Group B. These results show that PCR is the only accurate method to diagnose asymptomatic carriers, whereas serology and parasitology fail to detect them in a certain number of dogs.
Oral lesions of leishmaniasis in two dogs
A. BLAVIER, L. CHABANNE, J. L. CADORÉ, C. FOURNEL and G. BOURDOISEAU
Ecole Nationale Vétérinaire de Lyon, Marcy L’Etoile, France
Skin lesions are frequently reported in canine leishmaniasis (CL). Classical skin symptoms include diffuse nonpruritic symmetrical alopecia, silver white scales, asbestos-like scales, cutaneous or mucosal ulcers and onychogryposis. The nodular and the sterile pustular forms are unusual presentations of the disease. We describe two dogs with atypical mucosal nodules caused by Leishmania infantum. The first was a 7-year-old Siberian husky dog that was initially presented for sneezing, persistent cough, and dyspneic episodes occurring at night. On physical examination, several nodules were present on the tongue and some were ulcerated. Amastigotes of Leishmania infantum were observed on smears obtained by fine needle aspiration of the nodules. This dog was also diagnosed with eosinophilic rhinitis and pneumonia, all of which could have been related to the Leishmaniainfantum infection. The second case involved a 3-year-old giant poodle dog referred for hyperkeratosis and nonhealing ulcers on the footpads. Similar nodules were seen on the tongue and cytological analysis confirmed a diagnosis of CL.
Histopathology and immunohistochemistry of exfoliative dermatitis in canine leishmaniosis: a comparative study between lesional and normal looking skin
E. I. PAPADOGIANNAKIS, A. F. KOUTINAS, M. SARIDOMICHELAKIS and A. KARAMERIS
Faculty of Veterinary Medicine, Aristotles University of Thessaloniki; Department of Pathology and Molecular Biology, Military General Hospital, Athens, Greece
Exfoliative dermatitis (ED) is the most common cutaneous manifestation in canine leishmaniosis (CL). The aim of this study was to investigate the density of five leukocyte antigens (CD3, CD45RA, CD8α, CD8β, and CD4), and class II major histocompatibility complex molecules (MHC-II) in the epidermis and dermis. A total of nine dogs with spontaneous CL were entered into this study. Skin biopsies, obtained from lesional (Group A, n = 9) and nonlesional (Group B, n = 7) skin were processed for routine histopathology and immunohistochemistry (frozen sections stained by avidin-biotin peroxidase). An indirect immunoperoxidase method was used to demonstrate the amastigotes. The latter were present in only 5/7 biopsies from Group B. Mild to severe pyogranulomatous to granulomatous dermatitis was seen in both groups. However, histopathology was less severe in Group B than in Group A. The density of lymphocyte subpopulations, scored semiquantitively, was significantly greater in Group A only for CD8α+ and CD8β+ cells. The same was true for MHCII+ expression on Langerhans cells and keratinocytes. There was a weak to moderate presence of CD45RA+ cells that followed the inflammatory pattern. The number of CD4+ cells was almost equal to that of CD8+. In ED, microscopic lesions appear even in the nonlesional skin. The presence of parasites only in the latter may indicate an earlier stage of the infection as a smaller number of recruited CD8+ cells was found. Moreover, the antigen presenting cells of the epidermis may have not been activated yet.
Histopathology of canine distemper associated pedal hyperkeratosis (hard pad disease): a study of 16 clinical cases
A. F. KOUTINAS, W. BAUMGÄRTNER, D. TONTIS, M. SARIDOMICHELAKIS, Z. POLYSOPOULOU and S. LEKKAS
Aristotles University of Thessaloniki, Greece; Justus-Liebig University, Giessen, Germany; University of Thessaly, Karditsa, Greece
Canine distemper virus (CDV) may be associated with skin lesions, most commonly pedal hyperkeratosis. Histologically, it is characterized by severe orthokeratotic hyperkeratosis and the presence of eosinophilic inclusion bodies. The purpose of this study was to obtain more histological information on this disease and to localize CDV in the footpad tissue. Sixteen dogs ranging in age from 3 months to 4 years were used in the study. All of the dogs presented with neurological symptoms of CD (e.g. myoclonus, partial seizures, and spinal ataxia) and expressed CDV antigen in the skin of footpads. Clinical signs of pedal hyperkeratosis were present in 12/16 dogs. Sections of skin biopsy punches were stained routinely with H &E and CDV antigen was demonstrated by a standard avidin-biotin complex method. Histological examination revealed orthokeratotic hyperkeratosis (15/16), irregular acanthosis (14/16) with thickened rete ridges (13/16), pigmentary incontinence (7/16) and mononuclear perivascular (13/16) and mild periadnexial (9/16) dermatitis. An intracytoplasmic plus intranuclear CDV antigen expression was found mainly in the stratum spinosum and granulosum, the eccrine sweat glands and their ducts, and in fibroblasts, pericytes and endothelial cells of the superficial dermis. In contrast to what has been reported, neither CDV inclusion bodies nor intracytoplasmic vacuolation of the stratum spinosum cells were detected in any of our cases. Based on these findings, CDV-associated pedal hyperkeratosis requires tissue immunohistochemistry for a definitive diagnosis. CDV infection in the upper epidermal keratinocytes may have an impact on cellular proliferation and differentiation leading to the development of the hyperkeratosis.
Mechanobullous disease of Belgian foals resembles lethal (Herlitz) junctional epidermolysis bullosa of humans and is associated with failure of laminin-5 assembly
K. E. LINDER, T. OLIVRY, J. A.YAGER, J. D. BAIRD and G. MENEGUZZI
Ontario Veterinary College, University of Guelph, Guelph, Canada; College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, USA; School of Medicine, University of Nice, France
A mechanobullous disease, similar to human junctional epidermolysis bullosa (JEB), occurs in neonatal Belgian foals. Trauma-induced vesicles and bullae of skin and mucous membranes develop at birth, prompting euthanasia. Histologically, the lesion is a subepidermal bulla with the separation occurring through the lamina lucida. The disease is considered autosomal recessive; there is concern that the genetic mutations responsible are spreading through the North American Belgian horse population. This study further characterizes the ultrastructural lesions and identifies candidate genes for future genomic studies, with the aim of developing a screening test to identify healthy carriers. From two pure-bred Belgian foals, with clinical, histological and gross post-mortem findings consistent with JEB, skin and mucosal samples were collected for comparative EM, indirect immunofluorescent antibody (IFA) staining and immunoblot analysis of basement membrane zone (BMZ) proteins. Similar tissues from one clinically normal Belgian foal and non-Belgian adult horses served as controls. Electron microscopy revealed BMZ separation through the lamina lucida. Hemidesmosomes were severely attenuated, lacking an inner-plaque or subbasal dense plate. There was decreased IFA immunoreactivity to laminin-5 and its subunit chains γ-2 and β-3, whereas immunoreactivity to type XVII collagen appeared normal. Immunoblot analysis of BMZ proteins confirmed decreased expression of the γ-2 chain. Genes for the subunits of laminin-5 are being sequenced. Results are consistent with a failure of BMZ laminin-5 protein assembly and suggest a mutation in either the LAMC2 or the LAMB3 subunit gene. Belgian JEB is, thus, most similar to Herlitz-type JEB, a lethal form observed in humans.
A spontaneous canine homologue of human mucous membrane pemphigoid (cicatricial pemphigoid): autoantibodies recognize heterogeneous epitopes throughout the target antigen BPAG2 (BP180)
T. OLIVRY, M. SCHACHTER, L. XU, S. M. DUNSTON, M. P. MARINKOVICH and L. S. CHAN
College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina; School of Medicine, Stanford University, Palo Alta, California; School of Medicine, Northwestern University, Chicago, Illinois, USA
In humans, mucous membrane pemphigoid (MMP) is the denomination given to an autoimmune subepithelial blistering dermatosis previously known as cicatricial pemphigoid. It is characterized by vesicles, ulcers and scarring that affect primarily mucosae and mucocutaneous junctions with minor skin involvement. In human patients, circulating autoantibodies recognize epitopes on various basement membrane proteins such as collagen XVII, laminin-5 or laminin-6. We describe the clinico-pathological and immunological characteristics of eight dogs that had a dermatosis homologous to MMP in humans. These canine patients exhibited vesicles (7/8) or erosions (8/8). Lesions were present on mucous membranes or mucocutaneous junctions of the oral cavity (8/8), nose (6/8), conjunctiva (3/8), genitalia (2/8) and anus (2/8). Examination of lesional biopsies revealed subepithelial vesicles with few or no inflammatory cells (7/8). Direct immunofluorescence demonstrated IgG (7/8) or activated complement (2/8) at the dermoepithelial junction. Circulating basement membrane-specific IgG autoantibodies were detected in 8/8 dogs by means of indirect immunofluorescence using salt-split epithelial substrates. In seven dogs, autoantibodies bound the epidermal side of induced clefts and recognized various epitopes on collagen XVII, as determined by immunoblotting using canine epidermal cells and ELISA using synthetic peptides of the canine collagen XVII NC16A segment. In the last dog, IgG autoantibodies bound to the dermal side of salt-split epithelia and recognized epitopes in the 30 kDa carboxy-terminal segment of human collagen XVII using immunoblotting and recombinant peptides. Canine MMP, like its human counterpart, exhibits distinctive clinical signs and histopathological lesions, yet circulating autoantibodies target different antigenic epitopes.
Immunoadsorption of autoantibodies in human pemphigus foliaceus with baculovirus-expressed recombinant canine desmoglein 1
K. NISHIFUJI, M. AMAGAI, S. J. PARK, T. NISHIKAWA and T. IWASAKI
Veterinary Medical Teaching Hospital, Gifu University, Gifu; Keio University School of Medicine, Tokyo, Japan
Pemphigus foliaceus (PF) is an autoimmune skin disease that is recognized in both people and animals. The autoimmune target of human PF is desmoglein (Dsg) 1, a desmosomal cell-cell adhesion molecule. The purpose of this study was to produce a recombinant protein to represent the entire extracellular domain of canine Dsg1 with a proper conformation by the baculovirus expression system. We first demonstrated that IgG in human PF sera recognized the intercellular components of normal canine epidermis by indirect immunofluorescence. These sera were also capable of binding to the cell surfaces of living cultured canine keratinocytes, and this immunoreactivity was removed by preincubation of these sera with human Dsg1 baculoprotein. We next produced a recombinant canine Dsg1 by baculovirus expression system. The secreted form of canine Dsg1 baculoprotein was observed in the culture supernatant of High-Five insect cells. We lastly incubated 10 human PF serum samples either with canine Dsg1 baculoprotein or control supernatants and then performed living keratinocyte staining. Immunoreactivity of all PF sera was removed by preincubation with canine Dsg1 baculoprotein; control supernatant did not alter their immunoreactivity. These findings show that a recombinant canine Dsg1 can be produced to represent the major epitopes of the native canine Dsg1 by a baculovirus expression system. In addition, this immunoadsorption assay with baculoprotein combined with the living canine keratinocyte staining will be useful in studies to characterize the autoantibodies in canine pemphigus. This work was supported by Grants-In-Aid for Scientific Research from the Ministry of Education, Science, Sports, and Culture of Japan.
Efficacy of fipronil (Frontline® Top-Spot) against ear mites in cats
E. BENSIGNOR and E. GUAGUÈRE
Veterinary Clinic, Paris and Clinique Vétérinaire Saint Bernard, Lomme, France
Approved therapies for the treatment Otodectes cynotis require repeated applications, making client compliance difficult. Fipronil has proved useful in treating flea and tick infestations in dogs and cats, and also in the treatment of other parasite infestations. It has been used in limited trials in the treatment of ear mite infestations in dogs and cats. The purpose of this study was to evaluate the efficacy of Frontline® Top-Spot in the treatment of Otodectes cynotis infestation in cats. Cats presenting with clinically confirmed Otodectes cynotis infestations were used in the study. Cats were given a total clinical score based upon the sum of individual 0–4 scores for erythema, amount of cerumen, excoriations, and alopecia. Pruritus was also noted (auricular-pedal reflex). Fipronil was administered topically in the external ear canal. Efficacy of the treatment was assessed at 8, 28 and 56 days after the inclusion visit. There were 52 cats in this study. Total clinical scores ranged from 5 to 16 (mean 9.7). Forty-three cats (83%) presented with severe pruritus and the remaining presented with mild to no pruritus (17%). First follow-up visit showed a marked improvement in the clinical signs in 44 cats. No parasites were observed in 47 cases (90%). At the second follow-up visit, 45 animals (87%) were considered cured; however, seven cats had relapsed (13%). At the third follow-up visit, a relapse was noted in three cats. No adverse effect was observed during the whole study, except for a mild pruritus in one cat.
Newly recognized manifestation of trombiculosis with epithelial encystment in 12 dogs
P. BOURDEAU, F. DEGORCE-RUBIALES, C. BRETON and A. POUJADE DELVERDIER
National Veterinary School, Nantes, France; Laboratoire d’Anatomie Pathologique du Sud-Ouest, Toulouse; Laboratoire d’Anatomie Pathologique Vetopath, Antibes, France
The clinical and histopathological manifestations of a cystic parasitic disease are presented. Skin biopsies were collected from 12 rural dogs in southern France with a chronic generalized erythematous dermatitis with papules and suppuration. Previous treatments (antibiotics, corticosteroids, lindane or avermectins) were ineffective. Skin biopsies were fixed in formalin, routinely processed and stained with haematoxylin and eosin and PAS stains. In all cases, histological examination showed a ‘cystic’ reaction centred on a solitary parasitic element surrounded by an amorphous calcified layer. The organism appeared undamaged. The cyst wall had a pseudocarcinomatous hyperplastic stratified squamous epithelium that was undergoing abrupt keratinization with brightly coloured eosinophilic keratin. It resembled trichilemmal catagen follicle keratinization. Some cysts showed a keratin filled pore leading to the skin surface. This pore contained hair shafts, suggesting it originated from the follicular infundibulum. The surrounding dermis showed mucinosis, fibroplasia, oedema, neovascularization and a plasma cell infiltrate. The parasites (average size 213×486 μm) had a nonsegmented body, striated cuticle, grouped long legs, short rostrum, absence of blood in the body cavity, and long ciliated setae, suggestive of the genus Trombicula. In two cases, repeated skin scrapings documented the presence of Trombicula autumnalis. These cases differ from previous descriptions of trombiculosis. The lesions had an atypical distribution being generalized or more common on the head, the neck and the dorsum. Pain was more common than pruritus. This histological pattern could represent a specific and original epithelial model of reaction-rejection with encystment.
Flea bite hypersensitivity: new aspects on the involvement of mast cells in the pathogenesis
M. WELLE, U. V. RUEDORFFER, R. FISCH, P. ROOSJE, M. GRIOT-WENK and J. PEEL
University of Berne, Switzerland and Novartis Animal Health Inc., Switzerland
Flea bite hypersensitivity is a common skin disorder in dogs. Studies have shown that type I and IV hypersensitivity reactions are involved in the pathogenesis. Mast cells are known to be essential effector cells in an allergic response. However, the role of mast cell subtypes, characterized by their proteases chymase and tryptase contents, has not been investigated in canine flea allergy dermatitis. The purpose of this study was to investigate mast cell subtypes in flea-sensitized dogs after flea exposure. Flea-sensitized dogs (n = 28) and nonsensitized dogs (n = 5) were challenged with fleas. Control groups, consisting of sensitized (n = 12) and nonsensitized dogs (n = 9), were not exposed to fleas. Skin biopsies from control and challenge sites were taken before, and 24 and 72 h after flea application. Biopsies were processed for histopathology. Tissue sections were stained with haematoxylin and eosin, toluidine blue, anti-IgE, and an enzyme-immunohistochemical technique for tryptase and chymase. In addition, flea-specific serum IgE and IgG concentrations were measured and an intradermal skin test with flea antigen was performed. Repeated measures analysis of variance was used for statistical analysis (SAS/SAT computer program). Significant differences between the numbers and percentage of mast cell subtypes were detected after flea exposure independent of biopsy site between the four groups and the time points. There was no difference in findings with toluidine blue and IgE-stainings. Only sensitized dogs had positive intradermal skin tests and detectable flea-specific serum IgE and IgG antibodies. The surveyed data provide evidence that degranulation of mast cell proteases occurs after flea feeding, suggesting that they play a role in the pathogenesis of flea bite hypersensitivity.
Characteristics of generalized canine demodicosis and parasitological study on 103 cases
P. BOURDEAU, E. GUAGUERE, D-N. CARLOTTI, F. LE LOUARN and L. MARTIGNONI
National Veterinary School, Nantes; Clinique Vétérinaire Saint Bernard, Lomme; Cabinet de Dermatologie Vétérinaire, Mérignac; Novartis Animal Health, Rueil-Malmaison, France
The following is a summary of 103 dogs with generalized demodicosis and/or demodectic pododermatitis. Five lesional areas and one control area were skin scraped. Dogs were treated with milbemycin oxime 0.5–1 mg kg−1 orally once daily and when controlled, treated once monthly. There was a high prevalence of demodicosis in pure breed dogs (n = 44). Only 28% of cases were not secondary infected when lesions were extensive (> 50% of the body surface) compared with those having less extensive lesions (25%–50% of the body affected). Demodex mites were easily found in control areas (10.3 mites/Ssc). In comparison, there were 22.8 mites/Ssc in lesional areas. On day 0, mites were most prolific in lesional areas being highest in areas with secondary infections. The only significant difference between the 25% of dogs that rapidly cured and the 25% with the slowest response were a higher number of adults of Demodex at visits 2, 3, and 4. There were no significant differences in breeds, haircoat, size, sex, age, and duration of illness; previous treatment; or clinical presentation. At initial examination, indicators of a good prognosis were a low number of adult mites in lesional areas and absence of eggs in unaffected areas. On day 30, the indicators of a good prognosis were > 75% of dead mites. A parasitological cure of 85.7% was found on day 120 in this group compared with a cure of 69.2% on day 180 in dogs with < 75% of dead mites on day 30.
Treatment of canine scabies with twice weekly administration of milbemycin oxime (42 cases)
Veterinary Clinic, Paris, France
Treatment recommendations for canine scabies involve using either topical (organophosphates, amitraz) or systemic (ivermectin, moxidectin, milbemycin oxime) parasiticidal drugs. The efficacy of weekly treatment with milbemycin oxime has been reported to be as high as 100% in a North American study. However, in Swedish study, only 40/56 (71%) dogs were cured using this protocol. A recent comparison of various dosages has shown that alternate day administration of milbemycin oxime may be more effective than weekly treatments. The purpose of this study was to evaluate the efficacy of twice weekly oral milbemycin oxime for the treatment of canine scabies. Two dog kennels with a scabies infestation were used in this study. All dogs had mild to moderate (24 dogs, 57%) or severe (18 dogs, 43%) pruritus. Skin lesions compatible with scabies (papules, crusts) were present. Skin scrapings were positive for Sarcoptes scabiei (adults, larvae and/or eggs) in 15 dogs (36%) and were negative in six dogs (14%); skin scrapings were not done in 21 dogs (50%). All animals were treated with milbemycin oxime (Interceptor®, Novartis), at a dose of 2 mg kg−1 orally twice a week for three consecutive weeks. Clinical signs and severity of pruritus were assessed using a scoring index modified from the Canine Atopic Dermatitis Extensive Scoring Index (CADESI). The animals were evaluated each week during treatment and for 2 weeks after the last dose of milbemycin oxime. After 1 week, all dogs were less pruritic (average CADESI score reduced by 60%). After the last dose, either none or only mild pruritus and lesions were reported. Adverse effects were not observed.
Seasonal allergic dermatitis in sheep due to Phlebotomus perniciosus
L. ORDEIX, L. SOLANO-GALLEGO, R. RABANAL, M. BUADE, A. FONDATI and L.FERRER
Departament de Patologia i Producció Animals and Departament de Farmacologia i Terapèutica, Universitat Autònoma de Barcelona; Conselleria de Sanitat i Consum, Govern Balear, Spain
A seasonally pruritic dermatitis was studied in several flocks of sheep in the Mediterranean area. Lesions first appeared in May and spontaneously resolved by October. The affected animals (4%–6% of the flock) showed intense pruritus, erythema, papules and crusts that were distributed on the mid-ventrum and periocular region. Skin biopsies taken from three affected sheep showed irregular epidermal hyperplasia, hyperkeratosis, intraepidermal eosinophilic pustules and superficial and deep perivascular and interstitial inflammatory infiltrates composed mainly of eosinophils, plasma cells and lymphocytes. These findings were similar to a previous report and a diagnosis of insect hypersensitivity was made. Several mosquito traps were installed and Phlebotomus perniciosus was identified suspected to be the causative agent. An intradermal skin test with Phlebotomus and Culicoides antigen was performed in six animals (two affected and four nonaffected). Thirty minutes after antigen injection, the strong positive reactions were noted in the two affected animals to both dilutions of Phlebotomus test antigen. In the four sheep without lesions, two had negative reactions to both dilutions of Phelebotomus and two had positive reactions to only the most concentrated dilution. All six animals had mild positive reactions to the Culicoides antigen. There were no differences in serum IgE concentrations between the two groups. The overall data suggested that the seasonal pruritic dermatitis reported here was due to a hypersensitivity reaction to Phlebotomus.
Treatment of 36 cases of canine Sarcoptes using a 0.25% fipronil solution
W. BORDEAU and B. HUBERT
Unité de Parasitologie-Mycologie-Dermatologie, Ecole Nationale Vétérinaire d’Alfort, Maisons-Alfort Cedex; Clinique Vétérinaire Foch, Beziers, France
There are many topical and systemic therapies available for the treatment of Sarcoptes scabiei in dogs. However, some of these treatments are potentially toxic (e.g. the use of amitraz in Chihuahua dogs and ivermectin in collie dogs). In this study, we treated 36 cases of canine scabies using a 0.25% fipronil (alcohol-based) solution. Dogs were of various breeds and ranged in age from 6 week to 14 years, and weighed between 1.5 and 42 kg. Definitive diagnosis was confirmed by finding Sarcoptes scabiei mites and/or eggs on skin scrapings. Dogs were treated once weekly for 2 weeks with fipronil at a dose of 6 mL kg−1. The solution was applied with a sponge to ensure thorough contact with the skin surface. All in contact animals were treated with the same protocol. One month after treatment, the dogs were examined and skin scrapings were performed. Clinical examination revealed that lesions had resolved in the majority of dogs and pruritus was gone. All skin scrapings were negative at that time. The dogs were followed for the next 3 months and no relapses were reported. In addition, no adverse effects were noted with this therapy. Based on this clinical study, fipronil appears to be an effective alternative therapy for canine scabies. It is an especially attractive alternative to avermectins that are best avoided in puppies, pregnant and nursing bitches, debilitated animals, and breed sensitive dogs (e.g. collie). The major disadvantage of fipronil is the large quantity of solution needed to treat big dogs.
Evaluation of a commercially available serological test for the diagnosis of canine scabies
C. F. CURTIS
Dermatology Referral Service, Ware, Herts, UK
The definitive diagnosis of canine scabies can be problematic, consequently serological tests to demonstrate mite antibodies have become popular with laboratories claiming high (> 90%) levels of specificity and sensitivity. No independent reports have been published, so this study was designed to assess the accuracy of a commercial ELISA for the diagnosis of canine scabies. Serum samples from 37 dogs were submitted in a blinded fashion. Of these, 13 were normal, nonpruritic dogs, 12 were atopic (with positive intradermal reactions to Dermatophagoides farinae (DF) amongst other allergens) and 12 had sarcoptic mange, diagnosed by identification of mites/ova in scrapings. With optical density values of > 0.16 = positive, 0.145–0.16 = questionable and < 0.145 = negative, 11/13 nonpruritic dogs were negative and two were questionable, 12/12 atopics were negative and 10/12 scabies cases were positive; this corresponds to a sensitivity of 83% (10/12), specificity of 92% (23/25), positive predictive value of 100% and negative predictive value of 92%. In conclusion, this study demonstrates that a small proportion of dogs with scabies will have false negative results serologically, but that atopic dogs sensitive to DF antigen are unlikely to show false positive reactions. This is reassuring when one considers the cross-antigenicity between DF and S. scabiei, which has been shown to lead to sensitization to DF during S. scabiei infestations in both man and dogs. The author would like to thank the referring veterinary surgeons for the cases recruited and Set Bornstein of the National Veterinary Institute Uppsala, Sweden and Larry Roberts of IDEXX Laboratories, Wetherby Yorkshire UK for their technical and financial support of this study.
Long-term flea control in cats: relationship between clinical signs and flea burden
F. ASCHER, L. GARDEY and P. HOUFFSCHMITT
Virbac S.A, Carros, France
Using cats from households having had flea infestations in years past, 43 cats were assigned to a control group (placebo) and 46 to a treatment group (10% Pyriproxyfen spot on, 0.6 mL cat−1, Virbac). The cats were treated on days 0, 90 and 180. Fleas were counted before each treatment and every month from June (day 120) to October (day 240). Short-acting permethrin foam was applied to the cats to facilitate flea collection, if fleas were seen in the fur. Pruritus, erythema and lesions consistent with miliary dermatitis were scored (0 = none to 3 = serious). The flea populations decreased from winter to spring in both groups. Thereafter, they increased in the placebo group, while they remained near zero in the treatment group. At days 0, 90, 120, 150, 180, 210 and 240, respectively, the mean flea burdens were 1.09, 0.70, 2.00, 2.58, 4.74a, 5.57b, and 2.06 in the placebo group and 1.24, 0.33, 0.15, 0.52, 0.43a, 0.17b and 0.44 in the treatment group. On the same days, the clinical scores were 0.09, 0.16, 0.49, 0.58, 0.93c, 1.48d and 0.88e in the placebo group and 0.20, 0.13, 0.13, 0.39, 0.37c, 0.11d, and 0.21e in the treatment group ( anova, values with the same superscripts are significantly different). Convenience treatments against high flea burdens in placebo and the treatment group were recorded 18 and one times, respectively. Similar results were observed with subgroup analysis, i.e by comparing subgroups of cats which were either infested by fleas or not at inclusion. The relationship between flea burdens and clinical signs was clearly demonstrated as the clinical scores paralleled the flea populations.
Efficacy of selamectin in the treatment of nasal mite (Pneumonyssoides caninum) infection in dogs
L. GUNNARSSON, G. ZAKRISSON, D. CHRISTENSSON, A. UGGLA, V. CRACKNELL, D. DOMINGO and S. TOLLING
National Veterinary Institute (SVA) and Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden; Pfizer Animal Health, New York, New York, USA
The mite, Pneumonyssoides caninum, is a parasitic mite of the nasal cavity and sinuses of dogs. It was first reported in the USA in 1940. A recent investigation carried out in Sweden showed that 95 (20%) of 474 dogs submitted for necropsy were infected with P. caninum. Ivermectin and milbemycin oxime have been used to treat the mite; currently there is no licensed treatment. The purpose of this study was to evaluate the efficacy of selamectin in the treatment of P. caninum infestation in dogs. Twelve 4-month-old beagle dogs were used in this study. The dogs were housed in the animal facility of the Swedish National Veterinary Institute and each was inoculated with 24–41 nasal mites, as previously reported. Six to 11 days after inoculation, the dogs were randomly assigned to either a treated or an untreated (negative control) group. Selamectin was administered topically at a dosage of 6–24 mg kg−1 of body weight every 2 weeks for 6 weeks (i.e. three treatments). One week after the last treatment no nasal mites were found in any of the treated dogs at necropsy. In contrast, 4–23 nasal mites were found in five of the six untreated control dogs. Thus, selamectin appears to be effective against P. caninum infection. This study was supported by a grant from Pfizer Animal Health.
Treatment of solar-induced squamous cell carcinomas in dogs using cobalt radiation and environmental control
Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
The purpose of this study was to determine the effectiveness of combined cobalt radiation, surgery and environmental control on the remission period and/or cure rate of canine squamous cell carcinomas (SCC). The Johannesburg region has high levels of UV radiation, and thus SCC is a common tumour. There were 38 dogs (mainly bull terrier or Staffordshire terrier dogs) in this study. Patients were irrradiated every 48 h. The initial clinical appearance of the skin and response to radiation determined the number of treatments. Radiation dose was 2 Gy per treatment. The breed, age, sex, clinical and histiological gradings, pre/post radiation treatments, total number of Gys administered, degree of owner environmental compliance and period of remission were recorded. The owners were required to keep the dog out of the sun and/or to use a body suit which blocks 98% of UV. We were able to follow 17 dogs. Four dogs were euthanazed because of the SCC, five had a recurrence and eight had a remission of 12–30 months. There was a positive correlation between the initial appearance of the skin and the commitment of the owner and the period of remission. It was the clinical impression of referring veterinarians that this combined treatment plan had lengthened the remission period. It appears that the combination of radiation, surgery and environmental control lengthens the remission period in some dogs with SCC. Supported by University of Witwatersrand.
Use of acitretin in the treatment of canine epitheliotropic lymphoma
Park Veterinary Centre, Liverpool, UK
The use of retinoids in the treatment of canine epitheliotropic lymphoma (CEL) has been suggested by several veterinary dermatologists. Acitretin, a second generation retinoid, has not been used to treat CEL. In an open trial, five dogs with CEL were given acitretin (Neotigason®, Roche) at a dose rate of 2.5 mg kg−1 once daily. There were three golden retriever dogs, one corgi dog and one Bernese mountain dog, of which two were male and three were female. The mean age at the time of diagnosis was 10.5 years. Treatment response was determined by improvement in overall attitude of the dog and in the skin lesions. The time from first administration of the drug to euthanasia was also noted. All of the owners recognized an improvement in the dog’s attitude at the start of the treatment and an initial improvement in skin lesions. However, survival time was no better than that recorded in the literature for this disease. Mean survival time from first administration of the drug to euthanasia was approximately 4 months. It was concluded that acitretin seems to have some initial benefits; however, these are short lived. It does not appear that acitetin is a useful drug in the treatment of canine epitheliotropic lymphoma. Acitretin was provided by Roche Phamaceuticals.
Feline vaccine-associated sarcomas: an ultrastructural study of 20 tumours (1996–1999)
B. R. MADEWELL, S. M. GRIFFEY, M. C. MCENTEE and R. J. MUNN
School of Veterinary Medicine and School of Medicine, University of California-Davis, Davis, California, USA
Twenty feline vaccine-associated sarcomas were examined by transmission electron microscopy. Tumours contained pleomorphic spindle cells, histiocytoid cells and giant cells. Most tumours contained myofibroblasts that had morphological features similar to those of fibroblasts. These cells were further distinguished by subplasmalemmal dense plaques and thin cytoplasmic actin myofilaments organized as elongated bundles concentrated at irregular intervals forming characteristic dense bodies. Intracellular crystalline particulate material was found in five of the 20 tumours. One tumour contained budding and immature retroviral particles.
Leflunomide for the treatment of canine reactive histiocytosis
A. G. CANNON, V. K. AFFOLTER, J. PATZ, C. R. GREGORY and P. F. MOORE
Animal Dermatology & Allergy, Sacramento, California; School of Veterinary Medicine, University of California-Davis, Davis; California, USA
Canine Reactive Histiocytosis (CRH) encompasses a spectrum of histiocytic disorders including cutaneous histiocytosis (CH), in which lesions are limited to the skin, and systemic histiocytosis (SH), in which lesions involve the skin and other organs. CRH has a variable clinical course with lesions and symptoms waxing and waning and/or resolving or progressing. Lesions are characterized histologically by a sterile, pleocellular inflammatory infiltrate consisting primarily of activated dermal dendritic cells, lymphocytes and fewer neutrophils. The goal of therapy is to suppress the immunological response; corticosteroids are often ineffective with notable adverse effects, while cyclosporin A is expensive. This study evaluated a new immunomodulatory drug, leflunomide (Arava®, Hoechst Marion Roussel) for the treatment of CRH. Leflunomide is used in human medicine for the treatment of rheumatoid arthritis and in veterinary medicine for autoimmune haemolytic anaemia and prevention of kidney transplant rejection. Adverse effects in dogs include lymphopenia and gastric ulceration. Nine dogs diagnosed with CRH by histopathology and immunohistochemistry were treated with leflunomide at a dose of 2–4 mg kg−1, achieving leflunomide trough plasma levels of 20 mcg mL−1. All dogs responded after 7–10 days of therapy. Treatment was continued until there was complete remission. Lesions recurred when the dose of leflunomide was tapered, but resolved when reinstituted. Vomiting, lymphopenia and anaemia were uncommon adverse effects and treatment was not stopped in any of the dogs. Leflunomide appears effective for the treatment of CRH. Trough drug concentrations and complete blood counts monitoring for bone marrow suppression should be done. Hoechst Marion Roussel supplied leflunomide.
Ultrastructural, physicochemical, immunocytochemical and flow cytometrical characterization of feline eosinophils
A. FONDATI, D. FONDEVILA, A. IBORRA and L. FERRER
Departament de Patologia i Produccié Animals and Institut de Biologia Fonamental, Universitat Autònoma de Barcelona, Spain
Feline eosinophilic skin diseases are very common, yet feline eosinophils are poorly understood. The purpose of this study was to characterize the ultrastructural and biochemical constituents of feline eosinophils. In particular, we wanted to verify the existence of Major Basic Protein (MBP) in feline eosinophils. As part of the study design, fluorescein isothiocyanate (FITC) binding affinity to feline eosinophils was studied as a flow cytometric method to detect feline eosinophils. Eosinophils were collected through peritoneal lavage in two cats experimentally infected with Toxocara canis eggs followed by intraperitoneal injection of Toxocara antigen. Using this technique, 3847×106 nucleated cells, containing 85% eosinophils, were obtained and stored in liquid nitrogen. Ultrastructurally, electron dense oval granules were observed, as well as structures homologous to lipid bodies. Following sucrose lysis and homogenization of eosinophils, granule sedimentation by ultracentrifugation and acid-extraction of cationic proteins, proteins with a molecular weight homologous to human and rodent eosinophilic cationic proteins were identified in preliminary electrophoretic studies. The presence of a Major Basic-like Protein was immunocytochemically demonstrated with rabbit antihuman MBP antibodies (supplied by Dr G. J. Gleich). Feline eosinophils, unlike human eosinophils, were not selectively labelled by FITC in flow cytometric studies. These results indicate that large numbers of purified feline eosinophils can be obtained by peritoneal lavage and it appears that they possess MBP, which is similar to human MBP.
Feline paraneoplastic alopecia: retrospective study of seven cases
W. BORDEAU, E. GUAGUERE, E. BENSIGNOR and Z. ALHAIDARI
Unité de Parasitologie-Mycologie-Dermatologie, Ecole Nationale Vétérinaire d’Alfort, Maisons Alfort Cedex; Clinique Vétérinaire Saint Bernard, Lomme; Cabinet de Dermatologie Vétérinaire, Bordeaux; Cabinet Vétérinaire, Roquefort Les Pins, France
Feline paraneoplastic alopecia (FPA) is a recently described rare syndrome in which alopecia occurs in association with pancreatic or bile duct carcinomas. To date, only eight cases have been reported in the literature. Seven additional cases of FPA from France are described in this report. There were four female and three male cats (six DSH, one Siamese) ranging in age from 7 to 14 years (mean, 10.8). All of the cats had signs of systemic illness with most owners reporting lethargy, weight loss, or dysorexia. Digestive symptoms were observed in two cases, and an abdominal mass was palpable in two others. Dermatological examination revealed alopecia affecting the abdomen, thorax and/or limbs in all cases. Hair loss was not seen on the dorsum of the cats. Alopecia began on the abdomen in some cases and on the distal limbs in other cases. Mild erythema of the skin was seen in three cats. In contrast to other reports, pruritus was present in only one cat. There was a generalized shiny appearance of the skin. This latter change is unique and may be pathognomonic for FPA when compatible alopecia is present. Histopathological examination of skin biopsies revealed follicular telogenization, miniaturization and atrophy, and mild to moderate acanthosis with thinning of the stratum corneum. Hyperamylasemia and hyperlipasemia were present in one and two cats, respectively. The associated gastrointestinal tumours were either pancreatic adenocarcinomas or cholangiocarcinomas. Metastases were present in 5/6 cases. Six cats were euthanazed 3–26 week (mean 10.5) after the appearance of the skin lesions.
Collagenolytic granuloma in three domestic shorthaired (DSH) cats following foreign body penetration
L. CORNEGLIANI and A. VERCELLI
Ambulatorio Veterinario Associato, Torino, Italy
Three DSH cats were presented with a 2–3 week history of pruritic and painful skin lesions. Two were 3-month-old male cats with nodular, ulcerative lesions on the chin and pads. The third cat was a 5-year-old castrated male with nodules and ulcerated plaques on the lateral trunk and dorsal back. The first two cats lived together and were strictly indoor cats, whereas the third cat was an indoor-outdoor cat. Vaccinations were current and the owners practised flea control. When the lesions first developed, the cats were treated with a short course of oral cephalexin at a dose of 20 mg kg−1 twice daily with no response. Skin scrapings, hair plucking, dermatophyte culture and bacterial culture were negative. Cytological examination of skin impressions suggested an eosinophilic reaction. Skin biopsies were taken, routinely processed and stained with haematoxylin and eosin and Periodic acid-Schiff stains. The epidermis showed ulcers and hyperplasia. The dermis was infiltrated with eosinophils, mast cells and macrophages, with vertically orientated degenerate collagen bundles. A foreign body reaction surrounding fragments of vegetative material was seen under low magnification. A diagnosis of collagenolytic reaction secondary to the penetration of foreign material was made. Further investigation revealed that owners had cacti (Mamillaria spp.) in the home and the cats were in contact with them. Lesions resolved when the cacti were removed and recurred when reintroduced into the home. This case is interesting because the development of collagenolytic eosinophilic granulomas secondary to foreign bodies has not been reported to the authors’ knowledge.
Feline idiopathic ulcerative dermatosis
M. HEIMAN and J. FONTAINE
Institut de Pathologie et Génétique, Loverval and Bruxelles, Belgium
Eight cases of a dermatopathy resembling the feline idiopathic ulcerative dermatitis are reported. In contrast to other reports, the skin disease in these eight cats was much more severe and was associated with debilitation and death (spontaneous or euthanasia). Eight cats with this skin disease were followed for 2 years. The cats were of both sexes and were from 2 to 9 years of age when the lesion first developed. Clinically, the lesions presented as painful, large, chronic ulcerative plaques on the dorsal neck. In some cases, there was unilateral extension to the temporal area. There was no history of an injection at the site prior to lesion development. All treatments, either topical or systemic (e.g. antibiotics, glucocorticoids, cyclosporin) failed to improve the skin lesion. Three of the cats were FIV positive and one was FIV and FeLV negative but had a positive Toxoplasma titre (1:80). The other four cats had no abnormalities on routine blood testing and had negative serological tests for FIV, FeLV, and Toxoplamsa. Two of the cats died spontaneously, the cat with toxoplasmosis and another cat that had lymphocytic pancreatitis and a nephropathy. Histological examination of skin biopsy specimens showed a sharply demarcated ulcer with minimal inflammatory component, adnexal atrophy and vasculopathy of the small vessels of the deep dermis and subcutis. A variable degree of endothelial cell hyperplasia, fibrin degeneration of the walls, and a mild non-necrotic neutrophilic and lymphocytic infiltrate characterized the vasculopathy. The follicles showed pyknotic and apoptotic cells. In one case neural oedema was observed. The pathogenesis and aetiology of the feline ulcerative idiopathic dermatitis is not yet known and may involve a potential vascular, neural or infectious aetiology.
Cutaneous asthenia in Burmese cats: a vasculopathy?
G. BURTON, D. STENZEL and K.V. MASON
Animal Skin and Allergy Clinic, Glen Waverley, Melbourne; Analytical Electron Microscopy Facility, Queensland; University of Technology, Brisbane; Albert Animal Hospital, Pacific Highway, Springwood, Brisbane, Australia
Cutaneous asthenia is a genetic disease of cats characterized by hyperextensible and fragile, easily torn skin. Nine Burmese cats (four males and five females) ranging from 5 to 12 months of age were diagnosed with cutaneous asthenia based on clinical signs and ultrastructural skin biopsy finding. Clinical lesions consisted of necrotic eschars, atrophic alopecia and purpura. Tearing of the skin was not reported. Extensibility indices, routine histopathology, Masson’s-Trichrome stain and transmission electron microscopy (TEM) were performed on affected cats and two nonaffected controls. Hyperextensibility index of affected cats varied from 22% to 28%. Histological examination of lesional skin showed cutaneous infarction with wedged shaped epidermal and dermal necrosis. Adjacent skin showed follicular, dermal and epidermal atrophy. Routine histological sections from nonlesional skin of affected cats were normal in appearance. Masson’s-Trichrome stain showed positive staining for dysplastic collagen equally in all sections. TEM studies showed marked variation in collagen fibril diameter, irregular collagen arrangement and decreased perivascular collagen deposition when compared to the normal cats. Individual collagen fibrils showed ‘hair pin’ bends not seen in the normal control cats. The clinical and histological appearance of these lesions was consistent with vascular injury. Stretching of the blood vessels as a result of the hyerextensible skin or reduced collagen investment around vessels may predispose to vascular injury. Ischaemia (not tearing) is responsible for the clinical lesions seen. TEM and not routine histological staining or Masson’s-Trichrome stains differentiated affected from nonaffected animals. Study supported by Dermcare Vet Pty Ltd.
Efficacy of cyclosporin in the treatment of 12 cases of eosinophilic granuloma complex
E. GUAGUÈRE and P. PRÉLAUD
Clinique Vétérinaire Saint Bernard, Lomme; CERI, Paris, France
We report preliminary results on the use of cyclosporin in 12 cats for the treatment of indolent ulcers (IU), eosinophilic plaques (EP), and eosinophilic granulomas (EG). Cats in this study were evaluated for food hypersensitivity and flea allergy dermatitis. In the preceding 4 weeks, the cats had not received any antibiotic, antifungal or anti-inflammatory therapy. Cats were treated for 60 days with oral cyclosporin at a dose of 25 mg cat−1, 2 h before meals. A 0–4 scale was used to assess pruritus, severity of oral EG lesions, and for monitoring regression of lesion size. Cats were evaluated on days 0, 10, 20, 30, 60, and 90. The mean clinical scores were compared using Student’s t-test for unilateral matching series. The mean dose of cyclosporin was 4.9 at 12.5 mg kg−1. For the six cases of EP, there was a significant regression in lesion size (P < 0.005) and pruritus (P < 0.005) by day 10 and a total recovery at day 60. Pruritus was almost entirely gone by day 30. In one case, a slight relapse of lesions was observed on day 90. For the three cases of oral EG, we noted a 50% regression of the lesion size by day 10 and a total recovery by day 30. In one case, some oral cavity lesions reappeared on day 90. In the three cases of IU a partial regression of the lesion was seen, but the lesion never resolved. Statistical analysis was not possible for oral EG or IU due to small sample size. In conclusion, cyclosporin was a useful therapy for EP and oral EG, but a less satisfactory treatment for IU.
In vivo and in vitro evidence of type I hypersensitivity to food allergens in atopic dogs
R. ISHIDA, K. MASUDA, M. SAKAGUCHI, K. OHNO, A. HASEGAWA and H. TSUJIMOTO
Department of Veterinary Internal Medicine, The University of Tokyo, Tokyo; National Institute of Infectious Diseases, Tokyo; University, Kanagawa, Japan
For the diagnosis of food allergies in dogs, intradermal skin test (IDST) and serum IgE quantifiation for specific antigens are known to have limited usefulness. In this study, we found evidence of type I hypersensitivity to food allergens with in vivo and in vitro antigen-specific diagnostic tools such as lymphocyte blastogenesis response testing (LBT) and histamine release assay, in addition to IDST and quantification of serum IgE concentrations. Three atopic dogs showing positive responses to a single food allergen (wheat, corn, or beef) on IDST were used in this study. The results of serum IgE antibody quantification agreed with those of IDST in the dogs reactive to wheat and beef. In all three dogs, LBT to each food were shown with the stimulation indexes of 1.8–5.3 by 3H-thymidine incorporation assay. Antigen-specific histamine release from peripheral leukocyte fraction including basophils was measured by competitive radioimmunoassay. The highest percentage of histamine release found was at an antigen concentration of 100 ng mL−1 in the two dogs sensitized to wheat (8%) and corn (38%). The percentage of the histamine release in the dog sensitized to beef reached the highest level of 16% at the antigen concentration of 10 ng mL−1. These findings provided in vivo and in vitro evidence of type I hypersensitivity against food allergens in canine atopic dermatitis. Supported by a grant from the Ministry of Education, Science, Sports and Culture in Japan.
IL4 production by mast cells in the skin of dogs with atopic dermatitis
J. D. SINKE, V. P. M. G. RUTTEN and T.WILLEMSE
Faculty of Veterinary Medicine, Utrecht, the Netherlands
In human Atopic Dermatitis (AD), it is proposed that the initiation of skin lesions is driven by activation of local Th2-cells, characterized by the production of IL4. In a previous study we showed that in dogs only a small part of the IL4+ cells in atopic skin are CD4+ (T-helper cells). The objective of this study was to investigate whether mast cells can be related to the presence of IL4 in canine AD skin. In 10 dogs with AD the skin was biopsied at sites predisposed to AD. Skin biopsies from dogs with AD were graded according to clinical appearance: nonlesional atopic skin, acute atopic skin and chronic atopic skin. Tissue sections were stained for IL4 using an immunohistochemical method and subsequently for tryptase by an enzyme histochemical staining. In all three stages of AD skin, IL4+/tryptase+ cells accounted for approximately 20% of the total amount of IL4+ cells, the remaining cells were IL4+/tryptase-. It can be concluded that a distinct part of the IL4 present in skin of dogs with AD is derived from tryptase+ cells, presumably mast cells, and that the relative extent of this part is independent of the stage of skin lesion maturity. Comparison of these results with the previous study mentioned above shows that the remaining number of IL4+ cells can only partially be accounted for by CD4+ cells. Therefore further investigations will have to elucidate the origin of these IL4+ cells. Supported by Heska, Ft. Collins, Colorado, USA.
In vitro studies of anti-allergic drug effects using murine keratinocytes after passive sensitization
J. HOPPMANN and M. KIETZMANN
Institute for Pharmacology, Toxicology and Pharmacy; School of Veterinary Medicine, Hannover, Germany
We describe an in vitro model using passive sensitization of murine keratinocytes for the study of keratinocyte function in allergic skin reactions. Immortalized keratinocytes were cultivated in RPMI 1640. Mouse serum sensitized against toluene 2, 4-diisocyanate (TDI) and 1-chloro-2, 4-dinitrobenzene (DNCB) was added 2 days after seeding. Twenty-four hours later, cells were incubated in medium containing TDI or DNCB. Keratinocyte reactions were measured after 4–48 h. The release of tumour necrosis factor (TNF) and the production of nitric oxide were measured. Using this in vitro model, the effects of glucocorticoids were evaluated. The TNF release from untreated keratinocytes was undetectable. After the addition of sensitized mouse serum, there was no obvious increase of the TNF release. Passively sensitized keratinocytes showed a significantly enhanced TNF release and production of nitric oxide when TDI or DNCB were added to the medium. There was a concentration dependent inhibition of this effect by hydrocortisone and dexamethasone. In conclusion, treating the cells with serum from sensitized mice can induce passive sensitization of keratinocytes. An enhanced TNF release was measurable after challenge. This in vitro model of passive keratinocyte sensitization appears to be a suitable model for the investigation of antiallergic effects of drugs. Because of the observed antigen specificity, the model may also be useful as an additional tool for the in vitro diagnosis of allergy.
Differential expression of mRNA for IL-2, IFN-γ, IL-4, and IL-10 mRNA in peripheral blood mononuclear cells (PBMC) from patients with canine atopy
S. J. PARK, K. NISIFUJI and T. IWASAKI
Veterinary Medical Teaching Hospital, Gifu University, Gifu, Japan
Cytokines are direct mediators of inflammation and influence the progress and direction of many immunological reactions. Distinct cytokine-producing T cell subsets are known to play a major role in mediating many of the immunological and pathological features of allergic diseases. Therefore, we investigated the in vitro levels of IL-2, IFN-γ, IL-4 and IL-10 in peripheral blood mononuclear cells (PBMC) stimulated by polyclonal activator, to better understand the role of these cytokines in canine atopy. Ten dogs with canine atopy and eight nonatopic healthy dogs were used in this study. The expression of cytokines from PBMC stimulated by concanavalin A was measured by using reverse transcriptase-polymerase chain reaction (RT-PCR). To control for sample-to-sample variation in the quantity of mRNA and variation in the RT and PCR reactions, the mRNA levels of glyceraldehyde-3-phosphate dehydrogenase (G3PDH), a housekeeping gene, were determined in parallel. Data showed a significantly lower expression of IFN-γ mRNA (P < 0.05) and higher expression of IL-10 mRNA (P < 0.01) in atopic dogs compared to nonatopic dogs. IL-2 and IL-4 mRNA levels did not differ significantly between groups. The IL-4/IFN-γ ratio was greater than 1.0 in 9/10 atopic dogs and 4/8 nonatopic dogs. The ratio for atopic dogs was significantly increased compared to the control dogs (P < 0.05). The increased values for IL-4/IFN-γ ratio between the groups were attributed to decreased IFN-γ expression. These results showed a tendency for the PBMC of atopic dogs to express a type 2-like cytokine pattern.
Digital photography for measurement of skin colour in histamine wheals, a comparative study
L. BOYSEN and U. DAM
The Royal Veterinary and Agricultural University, Denmark
In dermatology, the clinical evaluation of skin colour is a subjective measurement. For some years, colourimeters based on the Commision Internationale de l’Éclairage (CIE) colour system have been used in human dermatology to provide numeric scores for skin redness. Recently, digital photography has revolutionized clinical photography and digital photos can be analysed with computer technique. The purpose of this study was to determine if digital photography could be used for quantification of redness in dynamic skin reactions like the wheal development. Redness values obtained from computerized analysis of digital photos were compared with values obtained by CIE-colourimetry. Ten dogs with uniformly pigmented pale skin were used in the study. The hair was removed from the lateral chest. Dogs were sedated and after 30 min rest intradermal injections with histamine were administered. At 0–60 min after injection, the histamine reaction site was scored clinically, photographed and skin colour measured with a colourimeter. Average red, green, and blue colours of the photos were converted into redness, quasi-a values. Based on the analysis of 180 photos and corresponding colourimetric measurements of skin redness, a significant correlation was found between the two techniques. Measured redness values vs. time of histamine injection followed the same pattern as the one seen clinically. By demonstrating its use in measuring development of redness over time, it now seems possible to use digital photography and image analysis as a tool for providing objective colour measurements in dynamic skin processes.
Total and allergen specific serum and fecal IgE responses to dietary change in dogs with suspected food hypersensitivity
H. A. JACKSON, C. CATES and B. HAMMERBERG
College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, USA
This study explores the dynamic changes in serum and fecal allergen specific IgE in a group of dogs suspected of having food hypersensitivity on the basis of clinical signs (pruritus and diarrhea), absence of other pruritic skin diseases and response to dietary allergen restriction. Five dogs were fed a commercially available soy hydrolysate diet for 9 weeks before oral challenge with milk. After a 12-day washout period for the soy hydrolysate their regular diet containing multiple allergens (including milk, wheat and corn) was reintroduced. Dogs were examined before and after each dietary change and given a clinical score reflecting evidence of pruritus. Serum and feces were also collected at these times. A worsening of cutaneous clinical signs developed in all dogs with milk challenge. Four dogs developed diarrhea and one dog vomited. No significant rise in fecal or serum milk specific IgE concentrations was noted, except in the dog that vomited. This was accompanied by a rise in total corn and wheat specific fecal IgE concentrations. Dermatitis was again induced by challenge with the regular diet in all dogs. This was accompanied by an increase in allergen specific and total fecal IgE concentrations in 3/5 dogs. Total serum IgE concentrations increased significantly in all dogs after this challenge. No consistent correlation between fecal and serum allergen specific or total IgE concentrations was observed. In conclusion, local gastrointestinal IgE production may reflect a specific response to dietary proteins in the pruritic dog and warrants further investigation as a marker of dietary hypersensitivity.
Sequence of the feline immunoglobulin epsilon constant region
E. WEBER, C. R. HELPS, A. P. FOSTER, A. C. F PERRY, T. J. GRUFFYDD-JONES, L. HALL, D. A. HARBOUR and W. P. H. DUFFUS
Heska Corporation, Fort Collins, Colorado, USA; Department of Clinical Veterinary Science, University of Bristol, Langford; Department of Biochemistry, University of Bristol, Bristol, UK
A feline splenic cDNA library was screened with a 32P-labelled cDNA probe encoding the canine IgE epsilon heavy chain subunit. A cDNA sequence of 1613 nucleotides encoding the complete feline IgE heavy chain constant region, as well as a portion of a variable region, was identified. A search of the GenBank database revealed an identity of 82% at the nucleotide level and 76% at the amino acid level between the feline epsilon heavy chain sequence and the canine homologue. In a separate study, feline genomic DNA isolated from whole feline embryo cells was subjected to polymerase chain reaction (PCR) amplification. PCR amplification was carried out using primers based on a partial genomic DNA sequence for the feline Cε gene resulting in a product of 683 base pairs. Following removal of an intron, the coding sequence yielded an ORF of 606 bp. The DNA sequence of the product was 99% identical to the cDNA sequence encoding the corresponding region of the feline Ig epsilon heavy chain. A single base difference between the sequences is silent and, hence, the proteins encoded by the two sequences are identical over the regions of shared sequences. The cloning and expression of feline IgE offers the possibility of the preparation of IgE–specific reagents to study feline allergic diseases.
Characterization of Dermatophagoides allergens using polyclonal and monoclonal anti-canine IgE
T. J. NUTTALL, J. R. LAMB, H. R. P. MILLER and P. B. HILL
Hospital for Small Animals and Centre for Inflammation Research; Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, UK
In contrast to humans, studies in atopic dogs using anti-IgGd and recombinant FcεRI suggest that a 98-kDa chitinase is the most important Dermatophagoides allergen, rather than Group 1 and 2 proteases. The aim of this study was to characterize allergens in different Dermatophagoides species using polyclonal and monoclonal anticanine IgE. Western blots prepared from extracts of D. farinae (DF) and D. pteronyssinus (DP) were probed with sera from house dust mite allergic (n = 25) and clinically normal (n = 22) dogs. Using the polyclonal reagent, 74% of the atopic sera recognized DF allergens and 26% recognized DP. In contrast, none of the normal sera recognized any DF or DP allergens. With the monoclonal reagent, 56% of the atopic sera recognized DF allergens and 20% recognized DP. However, 10% of normal sera recognized DF allergens but no reactivity was seen to DP. Using both polyclonal and monoclonal anti-IgE, all positive sera recognized the 98 kDa allergen in DF and DP, but no binding to Group 1 or 2 allergens was seen. In addition, the monoclonal antibody detected a 45-kDa allergen in 78% of DF positive sera. Preliminary sequence analysis suggests that this may be a novel allergen. These results confirm that, unlike humans, DF is the most significant house dust-mite in atopic dogs, and that dogs recognize different allergens to humans. The results also indicate that determination of clinically relevant allergens is dependent on the type of reagent used. This study was supported by the Wellcome Trust.
Six and 24 h intradermal skin test (IDST) reactivity to Dermatophagoides farinae in healthy dogs and dogs with atopic dermatitis
A. HILLIER, L. K. COLE, K. W. KWOCHKA and C. A. MCCALL
College of Veterinary Medicine, The Ohio State University, Columbus, Ohio; Heska Corporation, Fort Collins, Colorado, USA
The objectives of this study were to report the occurrence of late phase reactions (LPR) after IDST with Dermatophagoides farinae in healthy dogs and dogs with D. farinae-associated AD, and to assess any correlation between the presence of an LPR and clinical signs or serum D. farinae-specific IgE concentrations. Included in this study were six healthy dogs with no history of skin disease and 20 dogs with nonseasonal AD and immediate skin test reactivity to D. farinae. IDST was performed on all dogs with D. farinae at dilutions of 1:1000 and 1:50 000 w/v. Reactions were subjectively scored at 15 min, 6 h and 24 h. Dermatophagoides farinae-specific serum IgE concentrations were determined by Heska™ Allercept™ assay. Pruritus and clinical signs were scored on a visual analogue scale and an atopy index, respectively. Six-hour reactions were observed in healthy (3/12 possible reactions) and atopic (13/40 possible reactions) dogs and were more common at the higher concentration of allergen. Twenty-four hour reactions were observed at both allergen concentrations in atopic dogs (16/40 possible reactions), but not in healthy dogs. The majority of 24-h reactions (9/16) were not preceded by a reaction at 6 h. Mean serum D. farinae-specific IgE concentrations were significantly higher in dogs with positive 24-h reactions at the 1:1000 w/v concentration of allergen. Results of this study suggest that 24-h LPRs are of clinical significance and may be helpful in distinguishing between clinically and subclinically affected D. farinae-hypersensitive dogs. Supported by The Ohio State University Canine Research Funds and Heska Corporation.
Field efficacy of Revolution® (selamectin) against fleas on dogs and cats, as determined by flea comb count
K. W. KWOCHKA, K. M. BEALE, G. A. KUNKLE, C. A. SOUSA, D. GRAM, J. D. PLANT, A. CANNON and C. A. THOMAS
The Ohio State University, College of Veterinary Medicine, Columbus, Ohio; Gulf Coast Veterinary Dermatology and Allergy, Houston, Texas; University of Florida, College of Veterinary Medicine, Gainesville, Florida; Animal Dermatology Clinic, Sacramento, California; Animal Allergy and Dermatology, Chesapeake, Virginia; Animal Dermatology Specialty Clinic, Marina del Rey, California; Animal Dermatology and Allergy, Modesto, California; Pfizer Animal Health, Exton, Philadelphia, USA
The efficacy of Revolution® (selamectin) for the treatment and control of fleas on dogs and cats presented to veterinary dermatology specialists in various geographical areas of the USA was evaluated. Seventy-five dogs and 46 cats were enrolled in the study. Treatments were administered at a minimum unit dosage of 6 mg kg−1 of selamectin in the commercial formulation. On days 0, 30, and 60, selamectin was applied to the skin in a single spot at the base of the neck in front of the scapulae. One dog or cat in each household was required to have at least 15 fleas counted on day 0 prior to treatment for the household to be included in the study. No other topical or environmental flea control products were allowed during the study. On days 0, 30, 60, and 90 ± 9 days, a comb count was performed to determine the number of viable fleas present on each animal. Each animal in a household had its entire hair coat combed for a minimum of 5 min or a maximum of 30 min, until there were no fleas removed during a 1-min period. Percentage reductions in geometric mean flea comb counts for Revolution® treatments on days 30, 60, and 90 vs. day 0 were 90.6%, 97.0% and 98.0%, respectively. These results show that Revolution® used alone is highly effective in treating and controlling flea infestations on dogs and cats from various geographical regions of the USA. Supported by a grant from Pfizer Animal Health.
The efficacy of selamectin (Revolution®, StrongholdTM), in the treatment and control of flea allergic dermatitis in dogs and cats exposed to infestations of Ctenocephalides felis
S. K. DICKIN, M. G. MURPHY, R. BOND, I. S. MASON, M. PAYNE-JOHNSON, D. G. SMITH, A. D. JERNIGAN and T. G. ROWAN
Pfizer Central Research, Pfizer Ltd, Sandwich, Kent, UK; RBK House, Irishtown, Athlone, Co. West Meath, Ireland; Royal Veterinary College, North Mymms, Hatfield, Hertfordshire; Sunbury-on-Thames, Middlesex, UK; Pfizer Central Research, Pfizer Inc., Groton, Connecticut, USA
The efficacy of selamectin was evaluated in the treatment and control of flea allergic dermatitis (FAD) in two well-controlled studies. Twenty-two dogs and 24 cats with FAD (confirmed by intradermal testing, serum IgE or provocative flea challenge and clinical signs) were allocated randomly to treatment with placebo or selamectin administered topically at a minimum dosage of 6 mg kg−1. Dogs were treated on days 0 and 30, cats on days 0, 30 and 60. Animals were housed in simulated flea-infested home environments, and were infested with unfed viable adult fleas on days–13,–2, 14, 28 and 42; cats were also infested on days 56 and 70. Efficacy was assessed by comparing the clinical signs of FAD, including the duration of pruritic behaviour/day in dogs, within and between treatments, and by comparing the number of therapeutic interventions/animal between treatments. There were no mortalities or suspected adverse drug experiences during the studies. The mean number of therapeutic interventions/animal for selamectin compared with placebo was significantly lower (P = 0.0001) in dogs (P = 0.0 vs. 10.1) and cats (P = 1.0 vs. 13.5); no interventions were required in selamectin-treated cats after day 27. In dogs and cats, selamectin significantly reduced the incidence (dogs, P = 0.0158; cats, P = 0.0029) and severity (dogs, P = 0.0042; cats, P = 0.0241) of clinical signs of FAD and the daily duration of pruritic behaviour in dogs (P = 0.0164). Thus, selamectin was highly effective in the treatment and control of FAD in dogs and cats.
The control of flea allergy dermatitis in dogs and cats using Frontline® TopSpot™
K. A. HNILICA, L. MEDLEAU, R. ALVA, J. L. CASE, T. CLEKIS, T. R. MCARTHUR, R. A. BARRICK and P. JEANNIN
College of Veterinary Medicine, University of Georgia, Athens, Georgia; Case Veterinary Hospital, Savannah, Georgia; VCA St. Petersburg Animal Hospital, St. Petersburg, Florida; Altamaha Animal Clinic, Vidalia, Georgia; Merial Ltd, Iselin, New Jersey, USA
Flea allergy dermatitis (FAD) is one of the most common skin diseases in dogs and cats causing many medical skin diseases. The purpose of this study was to determine the efficacy of Frontline® TopSpot™ when used monthly for the treatment of flea allergy dermatitis in dogs and cats. Dogs 10 weeks old or older and cats 12 weeks old or older with clinical signs of flea allergy dermatitis were included in the study. Thirty-six dogs and 42 cats with clinical FAD and positive flea antigen tests were enrolled. Each animal was treated with Frontline® TopSpot™ every 30 days for 3 months as per label instructions. All coinhabitant pets also were treated with Frontline® TopSpot™ every 30 days. The flea allergic animals were evaluated on days 0, 14, 30, 60, and 90. Each animal was clinically monitored using standardized assessment scores for characteristic symptoms and lesions. Additionally, each animal was flea combed for 10 min at each evaluation point to identify adult fleas, eggs, and feces. After application of TopSpot™, flea counts were reduced by 98% in dogs and 94% in cats. An excellent to good response to Frontline® TopSpot™ was observed in 87% of dogs and 85% of cats. Overall, 97% of dogs and 92% of cats demonstrated clinical improvement during the study period. No adverse reactions were observed during the study. Frontline® TopSpotTM, when used alone monthly for just three treatments, provided excellent results for the treatment of flea allergy dermatitis in both dogs and cats. Supported by a grant from Merial LLC6.
A new concept of integrated flea control for dogs: pyriproxyfen medicated food
F. ACHER, L. GARDEY and P. HOUFFSCHMITT
Virbac S.A, Carros, France
Using dogs from households having had flea infestations in years past, we evaluated the efficacy of a medicated dog food for flea control. Starting in February (day 0) 40 flea free dogs were assigned to a placebo group (nonmedicated food) and 40 to a treatment group. All dogs were fed a complete and balanced dog food. The treatment group received 10 g of medicated food per kg bodyweight, daily for 7 months, i.e. 500 μg pyriproxyfen kg−1 day−1. Fleas were counted every month from May (day 60) to October (day 210). A short acting permethrin spray was applied to the dogs to facilitate flea collection. Pruritus, erythema and signs of flea allergy dermatitis were scored (0 = none to 3 = severe). Flea populations, nil at trial onset, increased from spring to mid-summer in the placebo group and decreased during fall. Flea burdens remained near zero in the treatment group. On days 0, 60, 90, 120, 150, 180 and 210, respectively, the mean flea burdens were 0.00, 2.20, 5.00a, 4.75b, 5.38c, 3.10 and 1.90 in the placebo group and 0.00, 0.33, 0.43a, 0.38b, 0.28c, 1.38 and 0.33 in the treatment group. On the same days, the clinical scores were 0.08, 0.58, 1.05d, 1.20e, 1.53f, 1.40g and 1.08h in the placebo group and 0.05, 0.25, 0.30d, 0.10e, 0.10f, 0.23g and 0.20h in the treatment group. ( anova, aatohh = values with the same superscripts are significantly different.) Convenience treatments against high flea burdens in the placebo and treament group were recorded 61 and six times, respectively. The percentage of zero flea counts was higher in the pyriproxyfen group (86%) than in the control group (57%) during the flea season (6 counts dog−1) (Chi square, P = 0.006). The relationship between flea burdens and clinical signs was clearly demonstrated as clinical scores paralleled flea populations.
Pyriproxyfen transfer from cat fur to the immediate in-contact environment
F. ASCHER, P. JASMIN, P. HOUFFSCHMITT and L. CRUTHERS
Virbac S.A, Carrosx, France; Professional Laboratory and Research Services, USA
The objective of this study was to determine if pyriproxyfen in a spot on formulation could be passively transferred to a cat’s bedding after being applied to the hair coat. The test product (CYCLIO® spot on) was administered once to 12 cats at a dose of 10 mg kg−1 pyriproxyfen (0.1 mL kg−1). A group of six cats was left untreated. Cats were kept for 71 days in enclosures with free access to transport carriers where there were resting boards covered with medium-pile carpeting. On 13 occasions between day 0 and day 71, three carpet samples from each cat’s bedding were collected and seeded with 50 flea eggs, 50 larvae and 50 pupae. Efficacy and impact of vacuuming were assessed through the percentage of ovicidal, larvicidal and pupacidal efficacy of pyriproxyfen passively transferred to carpet samples. The Kruskal–Wallis test was used followed by the multiple comparison Z-value test. The test group had > 95% ovicidal efficacy 2 days after on-animal treatment and remained at this level until day 71 (100% at days 3, 4, 5, 8, 22, and 71) (z-value > 1.96). On the vacuumed samples, the ovicidal efficacy was > 95% and was significantly different when compared to the untreated group from day 8 until day 22. Vacuuming had no impact on ovicidal efficacy. Larvicidal results were in the same range. Pupacidal results were satisfactory (> 95%) on day 8 only, and good (> 80%) when vacuumed. In this study, we found that pyriproxyfen spot on was passively transferred from cat fur to the cat’s environment and proved to be useful in integrated flea control. Study sponsored by Virbac.
A comparison of the efficacy of Frontline® Top Spot™, a permethrin-methoprene combination product (Control® One Spot™, Hartz), and a permethrin-pyriproxifen combination (Bio-Spot®, Farnam) against flea and tick infestations in dogs
D. R. YOUNG and A. AHN
Young Veterinary Research Services, Turlock, California; Merial, Ltd, Iselin, New Jersey, USA
To assess the efficacy of a fipronil product, a permethrin-methoprene combination product, and a permethrin-pyriproxifen combination product against flea and tick infestations in dogs, 32 dogs were allocated by restricted randomization on pretreatment flea counts to one of four groups: (1) untreated controls, (2) permethrin and methoprene (Control® One Spot™), (3) permethrin and pyriproxifen (Bio Spot®), and (4) fipronil 10% solution (Frontline® Top Spot™). All products were used according to label instructions. Each dog was infested with 100 unfed, adult fleas on day–1, and weekly from day 6 through day 27. Each dog was also infested with 50 unfed adults of Rhipicephalus sanguineus on day–1, and weekly from day 5 through day 26. On day 1, and then 24 h after infestation, fleas were counted. On day 2 and 48 h after each infestation, ticks were counted. All test products provided > 90% control of ticks for challenges at all time points, and although there were no significant differences between treatments, Frontline® had consistently higher efficacy than the other products. For each challenge, all treatment groups had significantly fewer fleas than controls (P < 0.05); however, only fipronil-treated dogs demonstrated flea control efficacy in excess of 98% for the duration of the study. Dogs treated with either One Spot™ or Bio Spot® had initially poor flea control efficacy (64% and 76%, respectively) 1 day after treatment. Within 21 days after treatment, flea control efficacy for both permethrin-based products had fallen below 90%. Flea control provided by Frontline® Top Spot™ was more rapid in onset, lasted longer and was significantly better (P < 0.05) than either One Spot™ or Bio Spot® at all time points.
Efficacy of a fipronil/(S)-methoprene combination spot-on product against the cat flea (Ctenocephalides felis) on dogs
P. C. JEANNIN, D. R. YOUNG, A. A. MARCHIONDO and R. A. BARRICK
Merial Limited, Iselin, New Jersey; Young Veterinary Research Services, Turlock, California, USA
A spot-on product combining fipronil (10% w/v) and (S)-methoprene (9% w/v) was developed to provide treatment and control of adult and developing stages of the cat flea. A study was conducted to confirm adulticidal activity and inhibition of egg hatch and adult flea emergence with the fipronil and (S)-methoprene combination compared to fipronil alone and (S)-methoprene alone. Thirty-two dogs were randomly allocated to treatment groups: (1) untreated control, (2) Fipronil, (3) (S)-methoprene, and (4) fipronil/(S)-methoprene combination. Treatments were applied once, topically on day 0 (0.067 mL kg−1). On days–12,–1, 21, and weekly to day 84 each dog was infested with approximately 200 fleas and comb counted the following day, or 24 h after treatment for the day–1 infestation. On days –11, 1, 22, and weekly to day 85 each dog was re-infested with approximately 200 fleas. Eggs were collected for 24 h from 3 days after each re-infestation. Dogs were then combed to remove all fleas. Aliquots of up to 100 eggs from each dog were incubated for 72 h and 35 days to determine egg hatch and to quantify adult flea development, respectively. Total flea control (adulticidal, ovicidal and inhibition of adult flea emergence activities combined) was provided for all fipronil-treated dogs through 5 weeks. In addition to excellent (> 95%) adulticidal activity over 5 weeks, the fipronil/(S)-methoprene combination provided significant and excellent (> 90%) control of emerging fleas, as determined by percentage egg-hatch and emergence of adult fleas for 12 weeks.
Efficacy of a fipronil/(S)-methoprene combination spot-on against Ctenocephalides felis on cats
A. A. MARCHIONDO, S. E. GREEN, D. H. WALLACE, R. A. BARRICK and P.C. JEANNIN
Merial Limited, Missouri Research Center, Fulton, Missouri; Merial Limited, Iselin, New Jersey, USA
A spot-on product combining fipronil (10% w/v) and (S)-methoprene (12% w/v) was developed to provide treatment and control of adult and developing stages of the cat flea. A study was conducted to confirm adulticidal activity and inhibition of egg hatch and adult flea emergence with the fipronil and (S)-methoprene combination compared to fipronil alone and (S)-methoprene alone. Thirty-two cats were randomly allocated to treatment groups: (1) untreated control; (2) fipronil, (3) (S)-methoprene, and (4) fipronil and (S)-methoprene combination. Treatments were applied once, topically on day 0 (0.5 mL cat−1). On days –12, –1, 21 and weekly to day 56 each cat was infested with approximately 200 fleas and comb counted the following day, or 24 h after treatment for the day–1 infestation. On days –11, 1, 22 and weekly to day 57 each cat was re-infested with 200 fleas. Eggs were collected for 24 h from 3 days after each re-infestation. Cats were then combed to remove all fleas. Aliquots of up to 100 eggs from each cat were incubated for 72 h and 35 days to determine egg hatch and adult flea development, respectively. Total flea control (adulticidal, ovicidal and inhibition of adult flea emergence activities combined) was provided for all fipronil-treated cats through 4 weeks. In addition to excellent (> 95%) adulticidal activity over 4 weeks, the fipronil/(S)-methoprene combination provided significant and excellent (> 90%) control of emerging fleas, as determined by percentage egg-hatch and emergence of adult fleas for 6 weeks.
Prevalence of flea infestations in dogs and cats during the winter months in Western France
P. BOURDEAU, P. BLUMSTEIN and C. FROMEAUX
National Veterinary School, Nantes, France
The aim of this study was to characterize the epidemiology and prevalence of flea infestations in dogs and cats during the winter months in Western France and to compare flea infested (P) and noninfested (NP) animals. Dogs and cats were examined for the presence of fleas over a 4-year period (1996–1999) from September to June. During the period between September and December of 1999, fleas were counted as follows: (A) flea faeces, (B) 1–5 fleas, (C) 6–10 fleas, (D) 11–20 fleas, and (E) > 20 fleas. The signalment of the animals and date of the last antiparasitic treatment were recorded. We found 335 dogs and 135 cats infested with fleas and compared this population to a noninfested population presented at the same time. For dogs, there was a progressive decrease in flea infestations from September (35.5%) through February (8.9%) followed by a progressive increase until June (13.8%). For cats, we found that they maintain a high infestation during the winter months (maximum in December, 30.9%; minimum in February, 17.6%). Only 9.8% of dogs and 12.5% of cats had more than 20 fleas. There was no difference in lifestyle between the P and NP groups and few differences in flea control treatment. Of 109 dogs treated with fipronil, 70.9% had been treated less than 2 months before the visit. These results suggest that the immediate environment is an important source of annual reinfestation. They also show how difficult it is to get effective prevention in the field when only traditional insecticides are used.
Prevalence of Malassezia spp. in feline nail folds: a cytological study
S. COLOMBO and L. CORNEGLIANI
Istituto di Patologia Speciale e Clinica Medica Veterinaria, Facoltà di Medicina veterinaria di Milano, Milano; Via M. Borsa 63, Milano, Italy
Malassezia pachydermatis is a commensal organism of canine skin. It also has been reported to be particularly prevalent in some dog breeds. Malassezia spp. paronychia has been described in atopic dogs. The purpose of this study was to evaluate the prevalence of Malassezia spp. in the nail folds of various cat breeds. Forty-six cats of different breeds (27 domestic short hair, 15 Devon Rex, four Persian) were evaluated. In each cat, using the sharp edge of a cotton swab debris from beneath two nail folds (front and rear foot) was collected. The sample material was pressed onto a glass slide, heat fixed and stained with Hemacolor®. For each slide, 10 oil immersion fields were examined, and yeast organisms were counted up to 10 yeast per HPF. We found no significant difference (P > 0.05) between the numbers of yeast isolated from front and rear foot. Malassezia spp. was undetectable in 18/46 (39%) cats. When DSH and Persian cats were grouped together, organisms were found in only 18/31 (58%) cats; the mean number of yeast per HPF was 0.59 (range 0.05–3.95). In contrast, Malassezia spp. was found in all Devon Rex cats, with a mean number of 8.63 yeast per HPF (range 5–10). A red-brown greasy material, similar to that described in atopic dogs with Malassezia spp. paronychia, was found on the claws of Devon Rex cats. In this study, Malassezia spp. was commonly isolated from the nail folds of Devon Rex cats, although no pedal pruritus was observed.
Effect of pH on the in vitro growth of Malassezia pachydermatis
J. L. MATOUSEK, K. L. CAMPBELL and D. J. SCHAEFFER
College of Veterinary Medicine, University of Illinois, Urbana, Illinois, USA
Acidic topical therapy preparations are occasionally used as adjunctive treatments for Malassezia dermatitis in dogs. The purpose of this study was to determine the pH that will inhibit the growth of these cutaneous microorganisms. Using NaOH and HCl, the pH of Sabouraud dextrose broth was changed in increments of 1.0 from a pH of 1.0–10.0. An unchanged sample of pH 5.6 was retained as a control. Each pH level was tested in duplicate. The broth was inoculated with 0.1 mL of a turbid culture solution of M. pachydermatis (ATCC # 52682). The samples were incubated in a shaker water bath at 36°C, with 100 oscillations per minute for 108 h. At 12-h intervals, 1 mL of the broth was placed into semimicro methacrylate cuvettes and percentage transmittance was measured at a wavelength of 600 nm using a spectrophotometer. No growth occurred at pH values of 1–3 or 9–10. Statistical analysis was used to determine if the slopes of pH from 5 to 8 were parallel. The results suggested that growth of M. pachydermatis is inhibited at pH levels lower than 4 or greater than 8. Growth may be delayed at a pH of 4, but small shifts in pH within the 4–8 range did not have major effects on the survival of M. pachydermatis. Further research will be required to determine the significance of these results in relation to the use of acidifiers to decrease cutaneous M. pachydermatis flora. This project was funded by Evsco Pharmaceuticals, an affiliate of IGI, Inc.
Could Malassezia dermatitis be diagnosed in animals other than pet carnivores?
J. GUILLOT, A. POUJADE-DELVERDIER, L. BOULOUHA and R. CHERMETTE
École Nationale Vétérinaire d’Alfort, Maisons-Alfort; Laboratoire d’Anatomie Pathologique Vétérinaire du Sud-Ouest, Toulouse, France
Over the last decade, the importance of Malassezia dermatitis has become obvious. Currently, the published reports describe Malassezia dermatitis in pet carnivores, especially in dogs. We describe the clinical and pathological in three horses, two sea lions (Zalophus californianus), one seal (Halichoerus grypus) and two canaries (Serinus serinus). All the animals were adults and presented with histories of chronic dermatitis of the hair or feather loss for several weeks. On culture, large numbers of Malassezia pachydermatitis were isolated from the skin of pinnipeds. Cultures were negative from skin lesions of birds and in horses only colonies of nonpathogenic filamentous fungi were seen. Histological examination of skin biopsies showed orthokeratotic hyperkeratosis of the epidermis associated with large numbers of Malassezia in keratin layers. Horses and pinnipeds were treated with twice weekly topical enilconazole. Canaries were not treated but recovered after Dermanyssus gallinae mites were eliminated. To date, we are unaware of any relapses in these animals. In conclusion, Malassezia dermatitis may be observed in a great variety of animals, including birds. The factors, which favour proliferation of Malassezia, are unknown, but probably vary according to the animal species.
Safety and immunologic effects of a combined live-inactivated dermatophytosis vaccine in cats
D. J. DEBOER, K. A. MORIELLO, J. L. BLUM, L. M. VOLK, L. K. BREDAHL and E. MAULDIN
School of Veterinary Medicine, University of Wisconsin, Madison, Wisconsin, USA; Alpharma AS, Oslo, Norway
An experimental combined live-inactivated dermatophytosis vaccine (CLIDV) was administered to cats, to determine if the vaccine causes adverse effects, and to measure the humoral and cellular immune response induced against dermatophytes. Kittens (n = 5 per group) were injected with CLIDV at recommended test dosage, or at two dosages up to 10 times higher. Control groups received either vaccine diluent or commercial killed dermatophytosis vaccine (KDV). Cats were observed for illness and local site reactions. Once monthly, samples were obtained for fungal culture, lymphocyte blastogenesis test (LBT) as an indicator of cell-mediated immunity against dermatophyte antigens, and antidermatophyte IgG levels by ELISA. Following vaccination, cats were challenged by topical application of 105 macroconidia of Microsporum canis. Weekly thereafter, cats were examined and scored for clinical signs of dermatophytosis. No vaccine-related systemic illness was apparent in any cat. Nine of 15 cats given CLIDV developed focal, spontaneously resolving, 5–10 mm superficial crusting at the injection site. Histologic findings and fungal culture confirmed these as sites of dermatophyte infection with the vaccine strain. Cellular immunity against M. canis increased gradually during the vaccination period but there was no significant difference between vaccinated and control cats. Antidermatophyte IgG titres increased significantly with all vaccination protocols. None of the vaccination protocols protected against challenge exposure with M. canis; all cats became infected. Vaccination with CLIDV or KDV was associated with a trend for reduced severity of initial infection, but did not result in earlier clinical cure of the resulting infection.
Combined continuous/pulse therapy with itraconazole in feline dermatophytosis: a pilot study
S. COLOMBO, L. CORNEGLIANI and A. VERCELLI
Istituto di Patologia Speciale e Clinica Medica Veterinaria, Facoltà di Medicina Veterinaria di Milano; Ambulatorio Veterinario Associato, Torino, Italy
Dermatophytosis is the most common feline infectious disease and it is a zoonosis. Itraconazole is effective and well tolerated in cats at 10 mg kg−1 orally once daily, but it is an expensive drug. Itraconazole is effective for the treatment of onychomycosis in people using a pulse therapy protocol of 200 mg orally twice daily once a week for 12 weeks. Itraconazole has been proven to persist into keratinized tissues for 3–4 weeks after the last dose. The aim of this study was to evaluate the efficacy of itraconazole as a combined continuous/pulse therapy for feline dermatophytosis. Nine cats with Microsporum canis dermatophytosis were treated with itraconazole at 10 mg kg−1 orally once daily for 28 days and then on an alternate week regimen (1 week off, 1 week on) at the same dosage. At day 28, cats were revaluated and a culture was performed. Cats were treated until mycological cure was obtained (two negative cultures at 2 weeks intervals). Eight were cured within 56 days of starting treatment with the first negative culture on day 28 and again on day 42. One cat required 70 days of treatment; the culture was positive on day 28. Negative cultures were obtained on day 42 and again on day 56. These results show that the above protocol is effective in the treatment of feline dermatophytosis. Further studies are needed to evaluate the efficacy of itraconazole on alternate week treatment regimen.
Efficacy of an experimental Microsporum canis vaccine in farmed foxes
L. K. BREDAHL, A. M. BRATBERG, I. T. SOLBAKK and A. LUND
Alpharma AS, Oslo; National Veterinary Institute, Oslo; Agricultural University of Norway, Aas, Norway
Dermatophytosis in fur animals has a financial and an animal welfare impact. During an outbreak caused by Trichophyton mentagrophytes in farmed foxes in Sweden, a Russian vaccine was used to control the disease. After two Norwegian fox farms experienced outbreaks caused by Microsporum canis, an experimental vaccine was manufactured. The nonadjuvanted vaccine contained live and inactivated components. Two efficacy trials were performed with 10 silver foxes (Vulpes vulpes) and 10 blue foxes (Alopex lagopus), respectively. In each trial, six foxes were vaccinated intramuscularly in the hind leg at 4 and 6 weeks of age. The remaining four animals served as unvaccinated controls. Five weeks after the second vaccination, the animals were challenged with a suspension containing a virulent strain of M. canis. The challenge material was applied topically on two clipped areas (5×5 cm) on the back. Clinical recordings were performed twice per week until lesion resolved. All silver fox controls and 3/4 blue fox controls developed lesions typical of dermatophytosis. The first reaction was seen 7 days after challenge, and lesions with crusts and scaling covering most of the innoculated area were present 14–28 days after challenge. The last of the controls had a milder reaction. The vaccinated animals had a transient reaction characterized by superficial scaling 7 to 14 days after challenge. To conclude, the experimental vaccine had a prophylactic effect against the experimental M. canis infection in both silver and blue foxes. This study was supported by the Norwegian Research Council and Alpharma AS.
Prophylaxis and therapy of trichophytosis of animals by the vaccine ‘VERMET’
A. N. PANIN, M. G. MANOYAN, K. P. LETYAGIN and K. A. SARKISOV
Veterinary Department, The All-Russia State Research Institute for Control, Standardization and Certification of Veterinary Preparation (VGNKI), Moscow, Russia
The most common causes of Trichophyton dermatophytosis in food producing animals are Trichophyton verrucosum and T. mentagrophytes. Previous experimental studies have shown that the use of an inactivated dermatophyte vaccine is less effective in the prophylaxis and treatment of Trichophyton dermatophytosis in animals. The use of an inactivated vaccine is less capable of inducing an immunological defense when compared to a live vaccine. We have investigated a number of strains of Trichophyton and selected the attenuated strains with the most effective prophylaxis and therapy potential. The vaccine ‘VERMET’ was developed after extensive laboratory and experimental animal studies. It was used in a large field trial on food producing animals. In this field trial, 1721 cattle, 331 sheep, 45 goats, 1930 camels, 168 nutria, 135 rabbits, and 150 foxes were immunized with ‘VERMET’ for preventive and therapeutic purposes. The vaccine ‘VERMET’ has shown high preventative and therapeutic efficiency in this trial. The adjuvanticity of ‘VERMET’ was tested by challenge exposure again confirming its efficacy for prevention and treatment. The immune stimulant effects in animals were marked after 12 months post-vaccination and continued for 5 years. ‘VERMET’ is now licensed for use and others are investigating its use. The Russian Federation has patented the strains and production methods.
The biochemical properties of dermatophyte cytosolic proteins
M. DROBNIC-KOŠOROK, J. KUZNER, P. ZRIMŠEK, I. ZDOVC and L. J. PINTER
Veterinary Faculty, University of Ljubljana and Veterinary Faculty, University of Zagreb, Croatia
The relative importance of various extracellular and intracellular dermatophyte proteins in the immune response and development of disease is poorly investigated, even though it is believed to play a key role in explaining the pathogenesis of dermatophytosis. Water soluble proteins, extracted from mechanically disrupted mycelia of Microsporum canis and Trichophyton mentagrophytes and two nondermatophyte fungal species (Malassezia pachydermatis and Aspergillus fumigatus), isolated from cats, dogs or rabbits were analysed by SDS-PAGE, Western blot analysis, sugar content analysis and enzymatic activity analysis. Non-dermatophyte fungal extracts can be easily differentiated from those of dermatophytes, showing differences at low molecular weights. The reactivity of the protein extracts with sera from naturally infected cats was studied using ELISA and Western blot analyses. The fungal cytosolic extracts were tested for the presence of serine and cysteine proteinases and inhibitory activity against trypsin and papain. Using substrate gel analysis, keratinolytic enzymes were only found in the dermatophyte extracts. In addition, strong inhibitory activity against trypsin and papain was also found. On the basis of these observations, 25–26 kDa inhibitors of cysteine proteinases were isolated from Microsporum canis and Trichophyton mentagrophytes cytosolic extracts by affinity chromatography on CM-papain Sepharose 4B, and their physicochemical properties were determined using ELISA and Western blot analysis, the immunlogical properties were investigated. Supported by Ministry of Science and Technology, Republic of Slovenia.
Microsporum canis virulence factors and immunogens: first purification and characterization of a 43.5 kDa keratinolytic metalloprotease
B. MIGNON, F. BROUTA, F. DESCAMPS and B. LOSSON
Faculty of Veterinary Medicine, University of Liège, Liège, Belgium
The design of vaccines against Microsporum canis infection in cats requires the identification of fungal immunogens and virulence-related factors involved in the host–fungus relationship. Recently, a 31.5-kDa keratinolytic, but weakly antigenic, subtilisin-like protease of M. canis was purified and characterized. The present study describes basic research devoted to the isolation, purification and biochemical characterization of another keratinase from M. canis. A keratinolytic protease, secreted by a feline clinical isolate of M. canis cultivated in a broth containing feline keratin as the sole nitrogen source, was purified by affinity chromatography on bacitracin-agarose and hydrophobic chromatography on octyl-agarose. The enzyme had an apparent molecular mass of 43.5 kDa and the pI was 7.7. The optimum pH was around 8. The enzyme has significant activity against keratin, denatured type I collagen (azocoll) and elastin. The apparent optimum temperature was around 50°C. The enzyme was strongly inhibited by 1,10-phenanthroline, phosphoramidon and EDTA. Its first 13 N-terminal amino acids showed 61% isology with the extracellular metalloprotease of Aspergillus fumigatus and with the neutral protease I of Aspergillus oryzae, confirming that this 43.5 kDa keratinolytic protease is a metalloprotease. Further investigations will be undertaken to determine if this newly described keratinolytic protease is involved in M. canis pathogenicity. Supported by the F.R.I.A. (Fonds pour la Formation à la Recherche dans l’Industrie et dans l’Agriculture).