NAVDF Abstracts 2008

Vectra 3D: a highly effective topical product for the control of all stages of fleas on dogs

Summit VetPharm, Fort Lee, New Jersey, USA

Molecules that affect new sites on insect receptors are necessary to combat insecticide resistance. Dinotefuran, the newest neonicotinoid based on acetylcholine rather than nicotine. Dinotefuran is a potent ACh agonist just like older neonicotinoids (i.e. imidacloprid). Studies suggest little potential for cross-resistance with earlier neonicotinoids. Vectra 3D™ featuring dinotefuran is highly effective against all stages of the flea life cycle in dogs and puppies. Eighteen dogs (21–55 pounds) were infested with 100 fleas on day 1. On day 0, treatments were applied (six control, six Vectra 3D, three K9 Advantix® and three Frontline® Plus). Dogs were combed for fleas at 2, 6 and 12 h post-treatment. Three Vectra 3D treated groups and one untreated group of six dogs (89–132 lbs) were infested on days 1, 8, 15, 22 and 29 with flea counts on days 2, 9, 16, 23 and 30. Eggs were collected on days 5, 12, 19, 26 and 32. Vectra 3D killed 60% of fleas within 2 h, and 96–100% within the first 6–12 h. This was faster than K9 Advantix® and Frontline® Plus, which achieved only 0–20% at 2 h and 50–60% within 6 h. For dogs > 90 pounds, flea reduction was > 99%. The pyripoxifen in Vectra 3D effectively inhibited egg development. These studies show that Vectra 3D™ kills fleas quickly and provides long-term control of immature stages of fleas.

This research was funded by Summit VetPharm, Ft. Lee, New Jersey, USA.

Determination of irritant threshold concentrations through serial dilutions in intradermal testing on healthy clinically nonallergic dogs

*Department of Small Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA, USA, †Statistical Consultant, Athens, Georgia, USA

The purpose of this study was to determine the irritant threshold concentration (ITC) for intradermal testing (IDT) in 40 healthy, clinically nonallergic dogs. Twenty-three allergens were tested at five variable concentrations ranging from 1000 to 8000 protein nitrogen unit (PNU) mL−1. To distinguish irritant reactions from subclinical IgE-mediated hypersensitivities, serum allergy testing was performed. ITCs were determined by evaluating the lowest concentration to which no dogs (0% cut-off) and to which at least 10% of dogs (≥ 10% cut-off) reacted. ITCs at the 0% cut-off were: 2000 PNU mL−1 (Ash, Lamb's quarter and Bermuda), 3000 PNU mL−1 (Bahia, Rye, Cocklebur, and Virginia Oak), 4000 PNU mL−1 (Maple and Mulberry), 5000 PNU mL−1 (Sorrel sheep), 6000 PNU mL−1 (Ragweed) and 7000 PNU mL−1 (Black Willow). ITCs at the ≥ 10% cut-off were: 2750 PNU mL−1 (Johnson), 3000 PNU mL−1 (Box elder), and 6000 PNU mL−1 (Bahia and Pigweed). For all other allergens, the ITC was > 8000 PNU mL−1 and could not be determined. No significant agreement between positive values was found for the same allergen on IDT and serum allergy testing for each dog, suggesting that reactions caused by the determined ITCs are less likely subclinical IgE-mediated reactions. No adverse reactions were observed to high IDT concentrations. These results suggest that ITCs may vary, that they may be very high for the allergens tested and that higher test concentrations may be used for IDT for the tested allergens without inducing an irritant reaction. Further studies are needed to evaluate the benefit of higher IDT concentrations in atopic dogs.

This study was funded by the American Academy of Veterinary Dermatology Research Grant. Material support was provided in part by Greer Laboratories Inc., Lenoir, NC, USA.

Pharmacokinetics and pharmacodynamics of hydroxyzine and cetirizine after hydroxyzine administration to healthy dogs

*Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, USA, †Department of Molecular and Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, USA

Pharmacokinetic parameters of hydroxyzine and its active metabolite cetirizine were determined after oral and intravenous administration of 2 mg kg−1 of hydroxyzine to six healthy dogs. Plasma drug levels were measured with high-pressure liquid chromatography. Pharmacodynamic studies evaluated the suppressive effect on histamine and anticanine IgE-mediated cutaneous wheal formation.

The mean absorption of oral hydroxyzine was 75%. Hydroxyzine was rapidly converted to cetirizine regardless of the route of administration. The mean area-under-the-curve was eight and 10 times higher for cetirizine than hydroxyzine after intravenous and oral dosing, respectively. The mean peak concentration of cetirizine was approximately 2.4 µg mL−1, compared to only 0.16 µg mL−1 for hydroxyzine. The terminal half-life for cetirizine was 11 and 14 h after intravenous and oral administration of hydroxyzine.

A sigmoidal relationship was fit to the data comparing cetirizine plasma concentration to wheal suppression. The concentration of cetirizine providing a 50% inhibition of wheal formation was approximately 0.6 µg mL−1, and it was maintained for 18–24 h after oral administration of hydroxyzine. Maximum inhibition was observed during the first 8 h, which correlated with a plasma concentration of cetirizine greater than 1.5 µg mL−1.

In conclusion, there was rapid conversion of hydroxyzine to cetirizine, with cetirizine concentrations more than 15 times higher than corresponding hydroxyzine concentrations. The inhibition of wheal formation appeared mostly due to cetirizine. Maximal pharmacodynamic response (> 80% inhibition) occurred during the first 8 h after oral hydroxyzine administration, supporting the likely benefit of twice-daily administration of this antihistamine.

The study was funded by the Morris Animal Foundation.

In vitro susceptibility of Pythium insidiosum and Lagenidium caninum to the phenylamide fungicide mefenoxam, and the antifungal agents terbinafine, itraconazole, voriconazole, posaconazole and caspofungin

Department of Veterinary Clinical Sciences, Louisiana State University, Baton Rouge, Louisiana, USA

The study objectives were to evaluate the radial growth assay as a technique for in vitro susceptibility testing of the pathogenic oomycetes Pythium insidiosum and Lagenidium caninum, and to assess susceptibilities of representative isolates to itraconazole (Sporanox: Janssen, Titusville, NJ, USA), voriconazole (Vfend: Pfizer, New York, NY, USA), posaconazole (Noxafil: Schering-Plough, Kenilworth, NJ, USA), terbinafine (Lamisil: Novartis, East Hanover, NJ, USA), caspofungin (Cancidas: Merck, Whitehouse Station, NJ, USA) and mefenoxam (ChemService, West Chester, PA, USA). Six isolates each of P. insidiosum and L. caninum were plated in triplicate onto agar amended with antifungal compounds diluted in dimethyl sulfoxide (DMSO) at concentrations of 0.025–8 µg mL−1. DMSO-amended agar served as controls. Mean colony diameter on test plates was compared to controls using one way analysis of variance and Dunnett's post-test. Assay variability was assessed by calculating coefficient of variation. For all isolates studied, colony growth was uniform, with a mean plate-to-plate coefficient of variation < 5%. For the azoles, no significant change in growth was observed at any concentration tested. Terbinafine did not alter growth of P. insidiosum at any concentration tested, but significantly reduced growth of L. caninum at ≥ 2 µg mL−1. Caspofungin significantly reduced growth of both pathogens at concentrations ≥ 2 µg mL−1. Mefenoxam significantly reduced growth of P. insidiosum at ≥ 0.05 µg mL−1 and L. caninum at ≥ 0.025 µg mL−1. Results suggest that the radial growth assay is useful for susceptibility testing of pathogenic oomycetes. Although terbinafine and caspofungin significantly reduced in vitro growth, only mefenoxam significantly reduced growth at concentrations likely to be achievable in tissue.

This study was funded by the American Academy of Veterinary Dermatology. The authors would like to thank Schering-Plough, Novartis, and Merck for supplying products used in this study.

Investigation of the pruritogenic effects of histamine, serotonin, tryptase, substance P and interleukin-2 in the canine

Veterinary Clinical Sciences Department, University of Minnesota, St. Paul, Minnesota, USA

There are numerous studies of the itch-producing effects of histamine, tryptase, substance P, serotonin and interleukin-2 in humans, but very little reported in dogs even though the most common reasons dogs present to veterinarians for skin-related problems involve itching. The objectives of this study were to determine whether substances known to cause itch in humans also cause itch in dogs. Twenty-five healthy research beagle dogs were included in the study. All dogs first received an intradermal injection of 0.05 mL of saline as a control substance and were video recorded for 20 min before and after the injection. Twenty-four hours later the dogs were divided into five groups of five dogs each and randomly assigned to receive histamine, tryptase, substance P, serotonin or interleukin-2 injected intradermally at 0.05 mL. On subsequent days, increasing concentrations of each substance were used. Before (baseline) and after the injection of each concentration of the itch- producing substances, the dogs were video recorded for 20 min. The frequency and character of itching behaviour (scratching, licking, rubbing, or rolling) were noted and these data were used for statistical analysis. The number of itching episodes was compared between baseline, saline, and the different concentrations of each substance. The results showed that dogs did not have a significant increase in itch behaviour above baseline or saline after injection from any of these substances (P = 0.07).

This study was self-funded.

Efficacy of eight commercial formulations of lime sulphur on in vitro growth inhibition of Microsporum canis

Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA

Lime sulphur is a common topical treatment for veterinary dermatophytosis. Until recently, a single veterinary lime sulphur formulation was available. The purpose of this study was to compare the efficacy of eight lime sulphur products for in vitro growth inhibition of Microsporum canis using the isolated infected spore model. Infective M. canis spores were isolated from hairs collected from untreated cats. Hairs were macerated in Triton-X solution and isolated according to a previously published protocol. Equal volumes of spore suspension and lime sulphur solutions were incubated for 5 min and plated onto modified BBL™ Mycosel™ agar (Becton, Dickinson and Company, Sparks, MD, USA) plates. Five plates were inoculated for each sample solution. Distilled water and bleach were used as controls. Colony-forming units (CFU) were counted daily for 21 days; neat plates contained > 300 CFU/plate. Seven of the products were supplied as concentrates and they were tested at label concentration, twice label concentration, and half label concentration. A prediluted product (SulfaDip®; Trask Research, Inc., Daluca, GA, USA) was tested at the label and half label concentration. All veterinary products formed recommended treatment dilutions of 3% sulphurated lime solution except one (LymDyp®; IVX Animal Health Inc., St. Joseph, MO, USA) which formed a 2.4% sulphurated lime solution. Results of the study showed complete growth inhibition of M. canis spores by all products at all dilutions tested. These results indicate that all tested lime sulphur-containing products were equivalent. Field studies are needed to test product equivalency in vivo.

Evaluation of trans-epidermal water loss in canine atopic dermatitis: a pilot study in beagle dogs sensitized to house dust mites

Department of Clinical Sciences, University of Florida School of Veterinary Medicine, Gainesville, Florida, USA

Trans-epidermal water loss (TEWL) was measured in sensitized beagle dogs (n = 24) before and after allergen challenge and compared to normal controls (n = 21). Dogs were matched for breed and age and housed in the same controlled environment. Ten sites were evaluated to include both areas predisposed to atopic lesions and other areas. On day 0 (baseline) and 3 (post-allergen challenge) clinical signs were scored using Canine Atopic Dermatitis Extent and Severity Index (CADESI), and TEWL measurements were taken using an open chamber evaporimeter (Cortex Technology, Hadsund, Denmark). Before allergen challenge, a one-way anova found significant differences between normal and sensitized dogs in the axilla, antecubital fossa, chin, periocular area, pinna and thorax. In sensitized dogs, a one-way anova found significant increase in TEWL after allergen challenge in the axilla, antecubital fossa, groin, pinna and thorax. Such difference was particularly marked in young dogs. In normal control dogs, allergen challenge did not change TEWL except for the chin. In sensitized dogs, a significant difference in TEWL was found between atopic and nonatopic predilection sites. It is concluded that sensitized dogs have altered barrier function in ‘atopic’ areas and that such differences are more evident in young individuals and are aggravated by allergen exposure.

This study was sponsored by the College of Veterinary Medicine, University of Florida, Resident Intramural Grant, an American College of Veterinary Dermatology Resident Research Award, and cyberDERM, Inc.

Comparison of subjective and objective intradermal test scores in dogs with atopic dermatitis: old school vs. new school scoring methods

Atlanta Veterinary Skin and Allergy Clinic, P.C. Atlanta, GA, USA

An intradermal allergy test (IDT) is an important diagnostic tool for identifying offending allergens in dogs with atopic dermatitis. No standardized method for teaching an inexperienced dermatology resident to grade an IDT has been developed. The purpose of this study was to determine if there was a correlation between a conventional, subjective IDT scoring method, based on wheal diameter, erythema and turgor (on a scale of 0 to 4) compared with an objective scoring method based on wheal diameter alone (length × width/2). The subjective scoring was performed by an experienced veterinary dermatologist (PW), while the objective scoring was performed by a dermatology resident (TH). Thirty-four clinically healthy, client-owned dogs diagnosed with atopic dermatitis were injected with 70 different allergens. Each dog was sedated with a 50 : 50 mixture of medetomidine (0.007–0.02 mg kg−1) and atropine IV. Then the fur over the left lateral thorax was gently shaved and 0.1 mL of histamine, saline or each allergen solution was injected intradermally. Injection sites were evaluated 10–15 min post-injection. The results were compared using both a statistical parametric (Pearson correlation coefficient) and a nonparametric (Spearman's rank correlation) correlation test. Our results indicate that there is a medium level of strength of positive correlation (0.47920 and 0.41322, respectively) between subjective and objective IDT scoring methods in these dogs.

Quantification of canine regulatory T-cell populations and serum interleukin-10 concentrations in healthy control dogs and canine atopic dermatitis patients receiving allergen-specific immunotherapy

*Department of Clinical Sciences, School of Veterinary Medicine, University of Illinois, Urbana, IL, USA, †Department of Pathobiology, School of Veterinary Medicine, University of Illinois, Urbana, IL, USA, ‡Department of Biosciences, School of Veterinary Medicine, University of Illinois, Urbana, IL, USA

Canine atopic dermatitis (AD) shares many similarities with human AD. Regulatory T cells (Treg) are a distinct lineage of T lymphocytes with various immunosuppressive properties including the down-regulation of allergic inflammation associated with IgE production. Antigen-induced Treg typically regulate immune homeostasis via productions of cytokines such as interleukin-10. Given the immunological similarities with human AD, it is likely that Tregs and the cytokines they produce play an important role in diseases of dogs as well. A cross-reactive FoxP3 antibody was used to identify a subset of CD4+ T cells in the blood of both healthy dogs and dogs with AD undergoing immunotherapy over a 1-year period. There was no significant difference in the Treg percentage over time in the healthy dogs. The immunotherapy group showed a significant increase in Treg percentage at 6, 9, and 12 months when compared to the healthy dogs (P < 0.001). A commercially available canine interleukin (IL)-10 ELISA kit was used to quantify the concentration of IL-10 in the serum of the same subsets of dogs. There was no significant difference in the IL-10 concentrations over time in the healthy dogs. The immunotherapy group showed a significant increase in serum IL-10 concentrations at 6, 9, and 12 months when compared to the control group (P < 0.001) and there was a significant difference between responders and nonresponders. We conclude from these studies that similar to humans undergoing immunotherapy, increasing Treg populations likely play a significant role in the success of this therapy for AD and other allergic conditions.

This study was supported by a research grant from Greer Laboratories, Inc.

Influence of inflammation and coat-type on oestrogen receptor alpha immunohistochemistry

*Department of Small Animal Clinical Sciences, †Department of Comparative Medicine, ‡Department of Pathobiology, University of Tennessee, Knoxville, Tennessee, USA

The purpose of this study was to evaluate oestrogen receptor alpha staining in a variety of breeds and skin conditions. The influence of inflammation and coat-type on the presence and intensity of oestrogen receptor alpha staining was evaluated. Approximately, 1700 haematoxylin and eosin (H&E)-stained slides were screened for the presence of small hair bulbs. Slides from 94 cases were selected and submitted for oestrogen receptor alpha immunohistochemistry. H&E-stained tissues were examined for inflammation and hair follicle stages. Oestrogen receptor alpha staining characteristics of telogen follicles, flame follicles, large anagen bulbs, small hair bulbs and capped bulbs were recorded. To assess the influence of inflammation and coat-type on oestrogen receptor staining of follicle types, chi-square tests, Fisher's exact tests, and logistic regression models were performed. Slides were classified as inflammatory (65) and noninflammatory (29). There were no statistically significant differences in oestrogen receptor staining when comparing inflammatory to noninflammatory biopsies or biopsies from different coat types. A subset of 13 noninflammatory biopsies with hair cycle abnormalities was identified. There was a statistically significant increase in the number of flame follicles in this subset as compared to all others. Comparison of oestrogen receptor staining of follicle types between biopsies from these cases and all other biopsies revealed a statistically significant increase in the number of mature telogen follicles stained in this subset. However, no statistical difference in staining of early follicle stages was noted. Therefore, the oestrogen receptor alone is unlikely the controlling factor for the transition from telogen to anagen.

This study was supported by the Center of Excellence, College of Veterinary Medicine, University of Tennessee.

Management trials of exfoliative cutaneous lupus erythematosus in German short-haired pointers with cyclosporine, hydroxychloroquine and adalimumab

*Departments of Pathobiology and †Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA, ‡Institute of Biotechnology and Advanced Molecular Medicine and the Center for Neurovirology, Thomas Jefferson University, Philadelphia, PA, USA

Six German short-haired pointers (GSP) with exfoliative cutaneous lupus erythematosus (ECLE) received immunomodulatory drugs to alleviate clinical signs (lameness, erythema, adherent scaling, erosions/ulcers). The diagnosis of ECLE was based on combined histopathological (cell-poor interface dermatitis) and clinical features. Six affected GSPs (two females, four males) were donated to the School of Veterinary Medicine, University of Pennsylvania, ranging in age from 6 weeks to 2.3 years of age. Five dogs received oral cyclosporine (Atopica®, Novartis Animal Health, Basel, Switzerland) at 2.5–10 mg kg−1 every 24 h for a minimum of 4.5 months and maximum of 2 years. In four dogs, the drug was combined with ketoconazole (5–7 mg kg−1 every 24 h). Cyclosporine decreased joint pain and stiffness and provided temporary improvement of skin lesions (mainly decreased erythema) but did not halt disease progression. No side-effects were seen (monthly complete blood count (CBC)/biochemistry screens). Three dogs received hydroxychloroquine 10 mg kg−1 every 24 h for 6 weeks, 6 months and 7.5 months, respectively, with no side-effects (weekly CBC/serum biochemistry screens, normal electrocardiogram). Hydroxychloroquine mildly ameliorated clinical signs in the two dogs on extended treatment. Four dogs between 1 and 3 years of age were euthanized due to disease progression. The two remaining male dogs (donated at > 1 year age) received a commercial human monoclonal tumour necrosis factor-α antagonist, adalimumab (Humira®, Abbott Laboratories) at 0.5 mg kg−1 every 2 weeks subcutaneously for 12 weeks. Biweekly CBC/serum biochemistry screens were within normal limits. Temporary improvement was seen in both skin lesions and lameness. None of the therapies provided long-lasting amelioration of clinical signs.

This study was funded by a grant from the American Academy of Dermatology and NIH grant RR02512 (National Center for Research Resources). The cyclosporine (Atopica®) was donated by Novartis Animal Health.

Effects of light exposure and temperature variations on time to growth of dermatophytes using commercial fungal culture media

School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA

Package inserts from commercial fungal culture plates often recommend specific conditions for incubation (i.e. temperature, dark incubation). The goal of this study was to evaluate the effect of temperature on the sporulation of Microsporum canis, M. gypseum, and Trichophyton spp. using commercial fungal culture plates and the effect of light exposure on M. canis growth. Six commercial dermatophyte fungal culture plates were inoculated with M. canis (three strains), M. gypseum and Trichophyton spp. and incubated at 25 °C (n = 5 plates) or 30 °C (n = 5 plates). Modified Mycosel® (BD Diagnostics, Franklin Lakes, NJ, USA) agar plates were inoculated with M. canis and incubated at 25 °C under four light conditions (n = 10 plates each): 24 h, 12 h, routine laboratory lighting (control) and 24 h darkness. All plates were examined daily for growth and sporulation using standard laboratory techniques. Fifty total plates were inoculated for each medium; five of six had 100% growth on all plates and one of six had 65% growth on plates. The mean number of days to sporulation for all media types varied from 2.6 to 3.65 days (25 °C) and 2.3 to 3.4 days (30 °C). Colony growth and sporulation were the same for all light exposures; colony growth was visible at 1 day with magnification and day 3 without magnification. Consistent sporulation was found at 5 days on all plates. In this study, days to growth and sporulation were not influenced by light exposure or temperature, however, one commercial medium was found to be less reliable in supporting growth of known pathogens.

A case report of superficial suppurative necrolytic dermatitis of miniature schnauzers with an identified causative agent using patch testing

*Animal Dermatology Center, ASC, Tokyo, Japan, †Daizawa Animal Hospital, Tokyo, Japan

Superficial suppurative necrolytic dermatitis (SSND) of miniature schnauzers is described as an adverse drug reaction to shampoo, but there are no reports to demonstrate its pathogenesis. A 9-year-old, castrated male miniature schnauzer was referred with papules, erosion and crusts on the dorsum diffusely, and pustules only on the pinnae after 5 days administration of an antimicrobial and prednisolone 0.2 mg kg−1 every 24 h. The owner noticed skin lesions on the second day after a grooming with SUPER PRO Aloe Shampoo SP-2 and Super-Rich Protein Lotion Conditioner. Blood tests showed neutrophilia, hypoalbuminaemia, and high levels of ALP and glucose. Histopathological findings revealed neutrophilic exocytosis with parakeratosis and acanthosis in the epidermis, and neutrophils infiltration in the superficial dermis. These findings were compatible with SSND, and prednisolone 1 mg kg−1 every 24 h and ofloxacin 5 mg kg−1 every 24 h were administered orally. Skin lesions had completely disappeared 2 weeks later, and then patch tests were performed with the Aloe shampoo and conditioner, and Norvasan Shampoo 0.5 as a control in both this dog and a clinically healthy dog. Only the site of the affected dog exposed to Aloe shampoo induced erythema after 48 h, and its histopathological findings revealed an epidermal infiltrate of neutrophils and eosinophils with parakeratosis in the epidermis, and infiltration of neutrophils, eosinophils and mononuclear cells in the superficial dermis. No clinical and histopathological abnormalities were observed at the other sites. Contact dermatitis due to Aloe shampoo was confirmed in this patient.

The use of linezolid to treat methicillin-resistant staphylococcal infections in dogs and cats

Department of Clinical Studies, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, USA

Linezolid (Zyvox: Pfizer, New York, NY, USA) is the first of a new class of totally synthetic antibiotics, the oxazolidinones. Linezolid has activity against gram-positive pathogens, but no effect on gram-negative bacteria and is only bacteriostatic against Enterococcus species. The purpose of this abstract is to report four cases of methicillin-resistant and multidrug-resistant staphylococcal infections successfully treated with oral linezolid. Culture and sensitivity testing (C & S) was performed in the North Carolina State microbiology laboratory on all four patients. Confirmatory tests were run by the microbiology laboratory to verify that that the staphylococcal organisms grown had a susceptibility pattern consistent with mecA gene strains. Three of the four patients were dogs (miniature poodle, dachshund, bulldog), and samples submitted for C & S were collected aseptically from intact pustules. Methicillin-resistant, multidrug-resistant Staphylococcus intermedius (MRSI) was reported from each of the three individual cultures. The culture sample from the fourth patient, a cat, was collected from abundant purulent exudate exuding from a deep infection of one hindpaw. Methicillin-resistant, multidrug-resistant Staphylococcus aureus (MRSA) was grown. The infection in three of the four patients was successfully cleared using 10 mg kg −1of linezolid every 12 h for 30–60 days, depending on the depth of the infection. The fourth patient, due to his size, required 8 mg kg−1 every 8 h for 30 days. None of the patients experience any side-effects and initially the owners had no problems administering the antibiotic. Eventually the medication had to be compounded into a capsule to dose the cat.

The clinical efficacy and concentration time course of pradofloxacin in the skin and serum of dogs with and without pyoderma

*Veterinary Teaching Hospital, School of Veterinary Medicine of California, Davis, California, USA (Current address: Animal Dermatology Clinic, Marina del Rey, California, USA), †Department of Medicine and Epidemiology, School of Veterinary Medicine University of California, Davis, California, USA, ‡Veterinary Teaching Hospital, School of Veterinary Medicine University of California, Davis, California, USA (Current address: Red Bank Veterinary Hospital, Tinton Falls, New Jersey, USA), §Department of Pathology, School of Veterinary Medicine University of California, Davis, California, USA

Pradofloxacin [PRA], a third-generation fluoroquinolone (Bayer Animal Health, Monheim, Germany), was developed to treat bacterial infections in dogs. The purpose of this study was to compare serum and skin concentrations of PRA in 20 control dogs and 20 dogs affected with pyoderma (affected and nonaffected skin), in addition to assessing clinical efficacy. Complete blood counts, biochemical profiles, and aerobic skin cultures were performed on dogs with pyoderma. All dogs received PRA (mean 3.7 mg kg−1, per os) once daily. Serum and skin biopsy specimens were obtained on day 0 prior to drug administration, on day 3 (prior to drug administration, 2 and 4 h postdrug administration) and additionally, on day 4 in 10 of 20 control dogs. Serum and skin biopsy specimens were assayed by high-performance liquid chromatography. While receiving daily PA, clinical efficacy for dogs with superficial pyoderma (12 of 20) was recorded at 4 weeks, and at 3 and 6 weeks for dogs with deep pyoderma (eight of 20). In dogs with pyoderma, PRA tissue concentrations in lesional skin were greater than values for serum and nonlesional skin at 2 h postdrug administration, as well as greater than serum and tissue concentrations of control dogs. Clinical improvement of superficial pyoderma was excellent at 4–5 weeks in nine of 12 dogs, improved in two of 12 dogs at 4–6 weeks, and one of 12 dogs developed a fluoroquinolone-resistant Staphylococcus intermedius pyoderma at 11 weeks. All dogs with deep pyoderma showed substantial improvement of lesions at 3 and 6 weeks. Complete resolution of deep pyoderma was achieved in one of eight dogs at 6 weeks.

PRA was supplied and the study funded by Bayer Animal Health, Germany.

Arteriovenous fistula manifesting as digital haemorrhages in a cat: diagnosis with 3D imaging

College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, USA

Arteriovenous fistulae (AVF) are defined as congenital or acquired abnormal direct communications between an artery and a vein, leading to shunting of blood. This report describes an unusual manifestation of acquired peripheral AVF in a cat, for which the diagnosis was confirmed by three-dimensional (3D) imaging. A 10-year-old female spayed domestic shorthaired cat was presented with a 2 months history of nonhealing, crusting, erosive to ulcerative skin lesions on the dorsal right forepaw. Severe chewing and biting, but not lameness, had been reported. Systemic abnormalities were not noted. Histopathology revealed moderately increased numbers of thin-walled and slightly grouped vascular profiles in the superficial and mid-dermis that were often markedly dilated and partially obscured by prominent hyaline deposits. There were few pyknotic nuclear fragments and haemorrhages in the wall as well as multifocal luminal thrombosis with or without recanalization. Scattered haemorrhagic crusts topped diffuse epidermal hyperplasia with small foci of necrosis. Differential diagnoses included progressive angiomatosis with trauma or AVF with secondary regional venous hypertension. Computed tomographic images were acquired using a 16-slice SOMATOM Sensation CT scanner and 3D images were created using Voxar 3D software. Image reconstruction revealed torturous aberrant vasculature on the medial aspect of the radius and around the carpus compared to normal vasculature on the contralateral limb. These changes were suggestive of peripheral AVF. The differential diagnosis for localized, nonhealing, bleeding crusted, erosive or ulcerative distal extremity skin lesions in cats should include acquired AVF, and diagnosis may be confirmed with digital imaging.

Funding: This study was self-funded.

Store-and-forward teleconsulting in veterinary dermatology: a preliminary study

*Studio Dermatologico Veterinario, Milan, Italy, †Centro Veterinario Prati, Rome, Italy

Teledermatology is a frequently used telemedicine application in humans, as evidenced by several recently published papers. It is considered to provide high levels of diagnostic accuracy. The purpose of this study was to assess the diagnostic value of teleconsulting in canine and feline dermatology. A total of 30 cases were submitted for teleconsultation. Three veterinary dermatologists selected 10 cases each from their files. For each case, one to four representative pictures of the lesion(s) (1000 × 750 pixels), together with relevant data (signalment and selected historical and clinical information), were sent for evaluation using a store-and-forward-based system. The three teleconsultants evaluated 20 cases each in an independent manner.

In 23 of 30 cases, questions included both differential diagnoses and diagnostic protocol, in three of 30 cases, diagnostic protocol and therapy and in two of 30 only diagnostic protocol or therapy were asked. Answers were examined separately by each dermatologist and considered correct if the definitive diagnosis was included among the three first differential diagnoses, if the diagnostic procedures useful to obtain definitive diagnosis were included in the diagnostic protocol and/or if the correct treatment was suggested. The definitive diagnosis was included in the three first differential diagnoses in 79.43% (mean) of the cases, the diagnostic protocol suggested by the teleconsultant would have yielded the right diagnosis in 85.04% (mean) of the cases and suggested therapy was correct in 100% of the cases. These results indicated that teleconsulting may have a diagnostic value in veterinary dermatology.

Microbiological and histopathological features of canine acral lick dermatitis

*Dermatology Clinic for Animals, Gilbert, Arizona, USA, †Southern Arizona Veterinary Dermatology, Tucson, Arizona, USA – currently employed with Animal Dermatology Clinic, Pasadena California, USA, ‡Dermatology Clinic for Animals, Las Vegas, Nevada, USA, §DVM Pathology Associates, Phoenix, Arizona, USA, ¶Department of Pathobiology, Veterinary Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA

The purpose of this study was to investigate the microbiological and histopathological features of canine acral lick dermatitis (ALD). Despite poor description of microbial characteristics, ALD is often empirically treated with antimicrobials based on surface cytology, surface culture or clinical appearance. Deep tissue infection may exist in ALD that differs in bacterial species or susceptibility patterns from superficial infections. Biopsies were obtained from 31 acral lesions and submitted for deep tissue aerobic, anaerobic and fungal culture, as well as histopathological evaluation. Surface aerobic culture and susceptibility and cytology were obtained for comparison. Skin scraping for Demodex mites and dermatophyte culture were performed. Bacteria were isolated in 30 of 31 cases. Staphylococcus intermedius was isolated in 56.9% of surface and deep bacterial cultures, with 10.3% being methicillin-resistant. Of all isolates, 24.1% were methicillin-resistant staphylococcal organisms, with an additional 14.3% of staphylococcal isolates resistant to ≥ 3 drug classes commonly used to treat staphylococcal infections. Of total isolates, 39.7% were multiresistant organisms. Of bacteria isolated from deep tissue culture, 57.1% and 54.9% were sensitive to potentiated amoxycillin and cefazolin. Cytology and superficial cultures did not correlate well with deep cultures. Microsporum gypseum was isolated from a single affected dog. No Demodex canis mites were identified. Histopathological features included acanthosis, follicular elongation, lymphoplasmacytic perivascular to periadnexal inflammation, folliculitis and furunculosis, perihidradenitis and hidradenitis, and vertical streaking fibrosis. Lesions associated with ALD warrant deep tissue bacterial cultures as the majority of cases yielded positive growth of bacteria often resistant to empirical drugs and different from superficial cultures.

This study was supported by the American Kennel Club Canine Health Foundation.

A retrospective analysis of skin diseases in pet rabbits

*Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California, Davis, California, USA, †Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, USA

This retrospective study's purpose was to document the most common skin diseases in domestic rabbits (Oryctolagus cuniculus) presented to a veterinary medical teaching hospital in northern California. The medical record database was searched for a 20-year period for pet rabbits with skin disease. Three hundred and thirty-eight rabbits met the inclusion criteria. Fifty-three different skin abnormalities were diagnosed. The 10 most common abnormalities included pododermatitis (83), abscess (66), focal or multifocal alopecia (53), fleas (48), otitis externa (40), moist dermatitis (39), otitis media (27), cheyletiellosis (21), myiasis (21) and ear mite infestation (20). Pododermatitis cases were classified as mild (54), moderate (9), severe (18) or unknown (2), and involved the hind feet in all cases and the front feet in three cases. Abscesses occurred most commonly over the mandible (30) and were frequently associated with dental disease. Pasteurella spp. (8), Fusobacterium spp. (7), coagulase-positive Staphylococcus spp. (6) and Streptococcus spp. (5) were the most frequently isolated bacteria from abscesses. Causes of alopecia, when noted, included barbering from a cage mate, self-trauma from ectoparasites and behavioural conditions. Statistically significant age, sex or breed predilections were not observed for the 10 most common conditions with two exceptions. Juvenile rabbits (< 1 year of age) were 3.61 times more likely to present with ear mites than adult rabbits (P < 0.05) and castrated males were 3.68 times more likely to present with alopecia than intact males (P < 0.05). Venereal spirochaetosis was diagnosed in two rabbits and myxomatosis was diagnosed in three rabbits over the 20-year period.

Comparison of culture and susceptibility results of superficial vs. biopsy specimens in dogs with superficial pyoderma

*Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, USA, †Southeast Veterinary Specialists, Metairie, Louisiana, USA

Bacterial pyodermas are a common problem in canine patients, with the majority of cases secondary to an underlying, primary disease. The sampling of epidermal collarettes, pustules and macerated tissue for culture and susceptibility testing (CST) has been validated in dogs with pyoderma. However, in the absence of either pustules or epidermal collarettes, tissue culture is often the only alternative. This study investigates the utilization of superficial crust samples for CST in dogs with pyoderma in comparison to skin biopsy. Ten dogs with clinical and cytological evidence of pyoderma were used in this study. Samples were obtained from the most clinically affected region. Adherent crust was harvested using sterile haemostats and submitted for CST. Biopsies from identical lesions, in close proximity, were also submitted for CST. Statistical comparison of the organism cultured and antibiogram pattern was calculated for each sampling procedure. Using the kappa statistic, the overall correlation between methodologies was 0.81, demonstrating strong concordance. The number of bacterial isolates and colony growth per technique was also recorded. Staphylococcus intermedius was the most frequent organism cultured from both methods, accounting for 48.15% (13 of 27) of the total bacterial isolates. The mean number of isolates per patient was 1.3 and 1.4 by the biopsy and superficial techniques, respectively. In general, colony growth was heavier from biopsy samples. Treatment based on crust CST resulted in resolution of pyoderma in all animals. This study exhibits strong correlation between the two methods and indicates that accurate culture results can be obtained from this straightforward, noninvasive superficial technique.

This study was self-funded.

The prevalence of apoptotic keratinocytes in feline epidermis: a retrospective study of skin biopsy specimens from 294 cats with inflammatory dermatoses

J. W. VOGEL*, D. W. SCOTT* and H. N. ERB†
*Department of Clinical Studies, Cornell University, Ithaca, New York, USA, †Department of Population Medicine and Diagnostic Sciences, Cornell University, Ithaca, New York, USA

Apoptosis is an important regulatory function of normal skin. Only a select group of inflammatory dermatoses in humans and domestic animals have been commonly reported to have epidermal apoptotic keratinocytes (AKs). Such information is strictly anecdotal in feline dermatology. The purposes of this study were to determine (i) the prevalence and number of epidermal AKs in various inflammatory feline dermatoses, (ii) the level(s) of the epidermis at which AKs occurred, and (iii) if certain feline dermatoses were more commonly characterized by epidermal AKs. Retrospectively, a total of 294 cat biopsies (haired skin, haematoxylin and eosin stain) with various inflammatory dermatoses and 33 normal cats were randomly reviewed by one author (JWV), who was blinded to diagnoses.

Three categories were created: (A) 33 normal, (B) 267 inflammatory dermatoses not expected to have AKs, and (C) 27 dermatoses expected to have AKs (systemic lupus, erythema multiforme, thymoma-associated exfoliative dermatosis, feline immunodeficiency virus dermatitis, herpesvirus dermatitis, and drug reaction). In total, 95 of 327 cats had AKs. Results showed a significant difference among the three categories (P < 0.0001) in the Kruskal–Wallis test (a one-way rank-based anova). Pairwise (two-sided analysis) comparisons were then performed at P = 0.05, and category C contained significantly more AKs than both category A and category B. Within category C, erythema multiforme contained significantly more AKs than systemic lupus erythematosus (P < 0.018), specifically in the spinous layer (P < 0.046). Category A and category B did not significantly differ from each other. Within category B, ectoparasitic dermatoses had significantly more AKs than the rest the dermatoses (P < 0.0034). A single cat in category A had an AK.

This study was self funded.