Abstracts from the American Academy of Veterinary Dermatology and the American College of Veterinary Dermatology Annual Meeting, Kansas City, MO, USA, 21–25 April 2004

A double-blinded pilot study on the use of azithromycin vs. cephalexin for canine pyoderma

*VCA Aurora Animal Hospital, Aurora, IL, USA
†Veterinary Specialists of Rochester, Rochester, NY, USA
‡Allergy Ear & Skin Care for Animals, Conshohocken, PA, USA

This study attempted to determine the efficacy of azithromycin (Zithromax, Pfizer, NY, USA) for the treatment of Staphylococcal superficial pyoderma in the dog. Dogs with Staphylococcal superficial pyoderma were randomly divided into three treatment groups: cephalexin, 22 mg kg−1 twice daily for 21 days (group A, control); azithromycin (5 mg kg−1) given two consecutive days a week for 3 weeks (group B); or azithromycin at 10 mg kg−1 on day 1, then 5 mg kg−1 on days 2–5 only (group C). Previously prescribed treatments for underlying conditions were allowed, excluding antibacterial and steroidal agents. All dogs were examined on days 0, 7 or 14 (randomly assigned), 21 and 42. The numbers and types of lesions were counted and recorded for each dog at each visit. Dogs that did not respond by day 21 were given a subsequent 21-day course of cephalexin dosed at 22 mg kg−1 twice daily. Twenty-four dogs were entered into the study; four dogs dropped out. Groups 1 and 2 contained seven dogs each. Group 3 contained six dogs. Lesions resolved by day 21 in 43% of dogs in groups A and B (3/7 each), compared with 67% (4/6) of dogs in group C. Sixty-seven per cent (2/3) of dogs in both groups A and B remained lesion-free on day 42, compared with 50% (2/4) of dogs in group C. This pilot study failed to reach statistical significance. Based on this study, azithromycin warrants further research as an antibiotic to be used in canine superficial pyoderma.

This study was funded by the University of Pennsylvania Small Animal Dermatology Fund.

Ciprofloxacin as a representative of enrofloxacin in disk diffusion susceptibility testing of middle ear tissue isolates

*Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio, State University
†DVM Pharmaceuticals, Inc.

In veterinary medicine ciprofloxacin is often used in in vitro susceptibility testing to represent all the veterinary fluoroquinolones. A previous study demonstrated that the use of ciprofloxacin minimum inhibitory concentrations does not provide adequate representation for assessing the susceptibility of the veterinary fluoroquinolones. The purpose of this study was to determine whether ciprofloxacin disk diffusion testing results could be used to assess the susceptibility of enrofloxacin for bacterial organisms isolated from the middle ear tissue from dogs with end-stage otitis externa. Tissue samples were obtained from the middle ear of 24 dogs undergoing a total ear canal ablation and bulla osteotomy that were enrolled in a study measuring enrofloxacin concentrations in the ear tissue. All dogs received IV enrofloxacin within a 24-h period of being sampled. The samples were routinely processed for bacterial culture and susceptibility testing. Sixty-seven organisms were identified and 13 (19%) discrepancies between enrofloxacin and ciprofloxacin were found: 2/18 (11%) Staphylococcus intermedius isolates; 2/11 (18%) Pseudomonas aeruginosa isolates; 5/10 (50%) Enterococcus isolates; 1/9 (11%) beta-streptococcus organisms; and 3/8 (38%) Corynebacterium isolates. Complete agreement was found for 4/4 Proteus isolates, 3/3 Escherichia coli isolates, 2/2 coagulase-negative staphylococcus isolates, and 2/2 nongroup D streptococcus organisms. Based on these results, for middle ear isolates, ciprofloxacin disk diffusion susceptibility results are not an adequate indicator of in vitro susceptibility of enrofloxacin.

This study was funded by Bayer Animal Health, The Ohio State University Canine Research Fund, The American College of Veterinary Dermatology, and the Ohio Animal Health Foundation.

Determination of clinical outcome compared with histopathology and direct immunofluorescence: a practitioner's perspective

Small Animal Clinical Sciences, University of Tennessee, College of Veterinary Medicine, Knoxville, Tennessee, USA

Diagnosing autoimmune skin disease can be a frustrating endeavour for veterinarians in general practice. Typically, skin biopsies are obtained and submitted for histopathological evaluation; however, some practitioners also routinely submit skin samples for direct immunofluorescence testing. The purpose of this study was to determine the clinical outcome of cases that had skin biopsies submitted for both histopathology and direct immunofluorescence. Forty-three cases were selected that had results for direct immunofluorescence as well as histopathology. The submitting veterinarian was then interviewed to determine the clinical details and outcome of each case. The submitting veterinarian's diagnostic conclusion was used to determine the sensitivity and specificity of histopathology and direct immunofluorescence. Based on the submitting general practitioner's final clinical diagnosis, histopathology demonstrated a sensitivity of 29% and specificity of 96%. Direct immunofluorescence demonstrated a sensitivity of 59% and a specificity of 81%. It is impossible to determine with certainty the final disease classification in these cases. Regardless, the practitioners diagnosed and treated each case based on their clinical impression and to a lesser degree based on the results of their diagnostic submissions. Most dermatologists regard histopathology as the diagnostic standard for identifying autoimmune skin diseases; however, these results suggest a lack of trust in and reliance on histopathology by veterinarians in general practice. The diagnostic reliability of skin biopsies can be improved through the proper selection of biopsy sites, the use of a dermatopathologist, and a complete and thorough histopathology report, including a discussion of the submitting veterinarian's clinical differential diagnoses.

Differential expression of selected cornification genes in Norfolk terrier dogs with a recessive mutation in keratin 10

*Comparative Dermatology Laboratory, Texas A & M University, College Station, TX, USA
†Anaderm, Pfizer Global Research and Development, Ann Arbor, MI, USA

A recessive mutation in keratin 10 (KRT10) has been identified in Norfolk terrier dogs. The mutation causes abnormal splicing and leads to premature termination with markedly decreased expression of KRT10. The first objective of this study was to determine the effects of decreased KRT10 expression on other genes of cornification, specifically keratin 1 (KRT1), keratin 2e (KRT2e) and transglutaminase 1 (TGM1), utilizing real-time PCR. The second objective was to assess whether culturing affected keratinocytes under organotypic conditions would create an in vitro model that displayed the same alterations in gene expression. KRT10 expression was markedly decreased in keratinocytes obtained from both skin biopsies and cell culture; however, KRT1 expression was decreased in culture while remaining unchanged in vivo. KRT2e was markedly decreased and TGM1 was mildly increased in cell culture while KRT2e was variably increased and TGM1 was mildly decreased in vivo. Consequently, cell culture proved to be an inaccurate method for simulating changes in gene expression that occurred in keratinocytes taken directly from skin biopsies. Mann–Whitney analysis of skin biopsies confirmed that the marked decrease in KRT10 and the mild decrease in TGM1 were statistically significant, with P-values of 0.0286. Although KRT2e appeared increased, due to the low number of samples and high degree of variability, this increase was not confirmed statistically. The unchanged level of KRT1 associated with markedly decreased KRT10 suggests that KRT1 may dimerize with additional type I keratins to help maintain cytoskeletal structure. Decreased TGM1 in vivo may be related to incomplete keratinocyte differentiation.

This study was funded in part by the Morris Animal Foundation. Dr Barnhart is the recipient of the AAVD Postdoctoral Fellowship.

Evaluation of adrenal function in small-breed dogs receiving otic glucocorticoids

Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida, USA

The objectives of this study were to evaluate adrenal function after otic glucocorticoid [dexamethasone (Tresaderm®, Merial Limited, Iselin, NJ, USA) and betamethasone (Otomax®: Schering-Plough Animal Health Corp, Union, NJ, USA)] therapy in small-breed dogs without evidence of otitis, and to evaluate the length of time needed for resolution of adrenal suppression after discontinuation of treatment. Fourteen clinically healthy, privately owned small-breed dogs (under 30 pounds) with normal ears and normal ACTH (adrenocorticotropin) stimulation tests were assigned to one of two treatment groups, receiving one of the medications at the manufacturers’ recommended dosage twice daily for 2 weeks. All of the dogs in the betamethasone treatment group had normal ACTH stimulation tests after 2 weeks of treatment. In contrast, 5/7 (71.43%) in the dexamethasone group had suppressed adrenocortical responses to exogenous ACTH. Of these five dogs, three dogs (42%) returned to normal values 1 week after discontinuation of the medication and two dogs (28.57%) returned to normal values 2 weeks after ceasing the medication. Statistical analysis was performed using the SAS Software (SAS Institute, Cary, NC, USA) PROC lifetest. A significant difference (P = 0.0072) was found to exist between the two groups return to normal cortisol levels after 2 weeks of therapy. In conclusion, it appears that adrenal function can be suppressed for up to 2 weeks in dogs receiving otic dexamethasone.

This study was funded by the University of Florida Resident Grant Competition and the American College of Veterinary Dermatology. Material support provided in part by Merial Limited, Iselin, NJ.

Evaluation of the frequency and significance of Staphylococcus schleiferi in canine ear disease

Department of Small Animal Clinical Sciences, University of Tennessee, Knoxville, TN, USA

Staphylococcus schleiferi is a newly recognized canine pathogen with possible implications for veterinary and human medicine. The purpose of this study was to determine the frequency of S. schleiferi isolation in ears of normal dogs and dogs with otitis and/or pyoderma. Otic cultures were obtained from 13 normal dogs, 10 dogs with normal ears and pyoderma, 11 dogs with otitis only, and 16 dogs with both otitis and pyoderma. S. schleiferi schleiferi was cultured from ears of three normal dogs, one of which had exposure to multiple antibiotics for urinary tract disease. S. schleiferi schleiferi was cultured from ears of two dogs with recurrent otitis and pyoderma, and from the skin of one of these dogs. S. schleiferi coagulans was not cultured from normal dogs but was isolated in three dogs with otitis only and from ears of six dogs with both otitis and pyoderma. In addition, S. schleiferi coagulans was cultured from the skin of two dogs with both otitis and pyoderma. Methicillin resistance was identified in 2/6 S. schleiferi schleiferi otic isolates and 2/9 S. schleiferi coagulans otic isolates. One out of two S. schleiferi coagulans skin isolates was methicillin resistant. Antibiotic resistance was associated with previous antibiotic therapy, with none of the isolates identified in normal dogs demonstrating antibiotic resistance. Staphylococcus schleiferi schleiferi can be found in normal dogs as well as dogs with otitis and pyoderma. Methicillin-resistant and -sensitive S. schleiferi schleiferi and S. schleiferi coagulans can be found in diseased ears as the predominant organism.

This study was funded by the Department of Small Animal Clinical Sciences, University of Tennessee.

Field evaluation of the cleansing and deodorizing efficacy of a physiological ear care solution

Medical Department, Virbac Laboratories, Carros, France

The study aimed to evaluate objectively, under real conditions of use, the efficacy of Virbac Physiological Ear Cleanser® (Virbac, Carros, France) in removing cerumen from the ear canal of dogs and neutralizing unpleasant aural smells. Forty-two healthy dogs with cerumen readily visible at the ear canal openings were included in the trial. Exclusion criteria were ear disease and treatment in the previous week with antimicrobial or anti-inflammatory agents. One of the dogs’ ears was randomly allocated to the cleanser treatment group, the remaining ear being left untreated. Veterinarians were unaware of the ear that was treated. One millilitre of cleanser was administered daily in the elected ear for 2 weeks by the owner. The ear cleanser contained micelles of nonionic surfactants, EDTA and a patented antiodour aldehyde complex. No other treatment was allowed. Quantity of cerumen in ears, aural odour and erythema were graded on a 5-point severity scale before (day 0) and at the end of the treatment period (day 15). Malassezia populations were also recorded by ear swab cytology. All clinical scores and Malassezia counts decreased markedly from day 0 to day 15 in cleaned ears (Wilcoxon signed-rank tests, P < 0.003, NCSS 2000 statistical software), but not in untreated control ears. Despite sustained frequent use, the cleanser did not cause local hypersensitivity, irritation or microbial proliferation in the canals but helped to decrease pre-existing erythema and Malassezia populations, where present. This effect is thought to have been caused indirectly by very efficient removal of cerumen.

This study was supported by Virbac Laboratories.

Frequency of urinary tract infection in dogs with chronic pruritic skin disorders receiving long-term glucocorticoid therapy – a retrospective study

Department of Small Animal Clinical Sciences, University of Minnesota, College of Veterinary Medicine, Veterinary Medical Center

Long-term glucocorticoid therapy is commonly used in the management of chronic canine pruritic dermatoses. Glucocorticoid therapy has been considered a predisposing factor for the development of urinary tract infections (UTI) by altering the systemic and local immune responses and local defense mechanisms through urine dilution. The purposes of this study were: (1) to determine the frequency of UTI in dogs with chronic pruritic dermatoses receiving long-term glucocorticoid therapy; (2) to evaluate the contribution of factors such as type of glucocorticoids, frequency of glucocorticoid administration, and dose and duration of therapy to the frequency of UTI and (3) to determine if urinalysis is a good indicator of UTI. One hundred and twenty-six records of dogs receiving glucocorticoid therapy for more than 6 months were reviewed. All dogs had urine samples collected by cystocentesis for bacterial culture and susceptibility. Chi-square test of homogenicity was performed to determine if type, frequency, dosage and duration of glucocorticoid therapy had an effect on the presence of UTI. Discriminant analysis using a forward stepwise procedure was carried out to determine if urinalysis parameters are useful in predicting UTI. The frequency of UTI was 18.25% (23/126). There were no significant differences regarding type of glucocorticoid, dosage, duration of treatment or alternate-day vs. daily glucocorticoid administration between dogs with or without UTI. It was determined that presence of white blood cells and bacteriuria can accurately predict UTI in 87.4% and 95.8% of cases, respectively. None of the other urinalysis parameters were good predictors of UTI.

This study was founded by the CVM Small Companion Animal Research Grant 2003, University of Minnesota.

Histology of ferret skin from 3 weeks to maturity

*Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Purdue University, West Lafayette, USA
†Lilly Research Laboratories, Eli Lilly and Company, PO Box 708, Greenfield, IN 46140, USA
‡Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Purdue University, West Lafayette, USA
§Department of Pathobiology, School of Veterinary Medicine, Purdue University, West Lafayette, USA
¶Department of Basic Medical Sciences, School of Veterinary Medicine, Purdue University, West Lafayette, USA

The purpose of this study is to describe the histology of ferret skin. The ferret is an important companion animal that suffers from a multitude of cutaneous diseases where dermatohistopathology is an important diagnostic tool. Skin samples were obtained from 41 ferrets in May and were grouped according to five ages and subdivided by sex. Thirty sites were biopsied. At each site five replicate measurements were made of the epidermis and dermis utilizing light microscopy and a micrometer. Repeated measure of variance was performed to determine an association between skin thickness measurements and age or gender. Statistical analyses employed SAS version 8.2 software and a P-value of < 0.05 was considered significant. In contrast to what is documented in the literature for ferrets, apocrine glands were found in the majority of locations. Sections from all sites revealed a prominent acidophilic layer superficial to the stratum granulosum. The youngest group demonstrated compound hair follicles, not the simple follicle morphology as documented for dogs of comparable stage. Age-dependent differences were: (1) the dermis of the young ferrets consisted primarily of fibroblasts that later differentiated to a population of fibrocytes with dark nuclei; (2) epidermal thickness of the youngest group was greater than the remaining groups in the majority of locations measured (16/30 locations); (3) anagen follicles were the more prevalent stage in the younger age groups; and (4) the dermis increased in thickness with maturity. In summary, the basic histological components of ferret skin are essentially similar to other domesticated carnivores.

Human recombinant interferon (alpha 2b) for management of idiopathic recurrent superficial pyoderma in dogs: a pilot study

*Animal Allergy & Skin Disease Center, Indianapolis, Indiana, USA
†Department of Veterinary Pathobiology, Purdue University, West Lafayette, Indiana, USA

Interferon has been used anecdotally to treat recurrent pyoderma; however, there are no reported double-blinded, placebo-controlled studies to document its effectiveness. The purpose of this pilot study was to provide preliminary data to determine if the oral use of human recombinant interferon alpha-2b (Intron-A, Schering-Plough, Kenilworth, NJ, USA) is effective for management of idiopathic recurrent superficial pyoderma in dogs. Eleven dogs with well documented histories of nonseasonal, recurrent superficial pyoderma, over 1 year in duration with a relapse rate of 6 weeks or less, for which an underlying cause could not be determined, were entered into a double-blinded, placebo-controlled, 18 week study. All dogs received oral antibiotics based on culture and sensitivity testing for the initial 6 weeks of the study. Dogs were given either interferon (1000 IU) or placebo (one mL sterile saline) orally and daily, from week 0 through to week 18. Each dog was evaluated at the end of antibiotic administration and monthly thereafter for 3 months using a standard scoring system. A general linear model with generalized estimating equation (GEE) for ordinal data was used to determine if there were significant differences in the clinical score between the treatment and placebo groups at each time point as well as for all time points combined. The use of human recombinant interferon alpha-2b was not found to be significantly more effective than placebo treatment for management of idiopathic recurrent superficial pyoderma. Further investigation is needed to determine whether interferon is effective for long-term treatment of idiopathic recurrent superficial pyoderma.

Inability to differentiate between dogs sensitized to soy antigen and nonsensitized control dogs after challenge with three different diets using a species-specific assay for C-reactive protein

*Department of Small Animal Medicine and Surgery, Texas A & M University, College Station, TX, USA
†Department of Pathobiology, Texas A & M University, College Station, TX, USA

The purpose of this study was to test the hypothesis that dogs sensitized to soy could be differentiated from nonsensitized control dogs using a species-specific assay for canine C-reactive protein (CRP) after challenge with three diets in a cross-over design. Eight dogs were sensitized with six food allergens (beef, corn, chicken, wheat, milk and soy) by repeated subcutaneous injection. Seven dogs served as nonsensitized controls. All dogs were fed an elimination diet containing egg and Brewer's rice for 6 weeks and were fasted the night before sampling. Blood was collected via jugular venipuncture. The serum was separated and stored at −80 °C. Dogs were assigned to three groups and were fed a diet primarily consisting of hydrolysed soy, whole soy or corn. After a 3-week challenge, blood collection was repeated and dogs were switched back to the elimination diet for 6 weeks before being switched to the next diet. The Tridelta Phase™ range canine CRP solid phase sandwich immunoassay was used to quantify C-reactive protein concentration in the serum samples. Statistical analysis was performed using Prizm Software©. P-values of < 0.05 were considered significant. There was no statistically significant difference between sensitized and control dogs across all diets. Further, there were no statistically significant differences when comparing sensitized and control dogs for each individual diet. Although there were significant differences in measurable IgE between groups, we were unable to differentiate these groups based on serum CRP concentration as a marker of inflammation.

Internal funding was used to support this project.

Pemphigus foliaceus in the horse – 13 cases

Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, USA

To evaluate the age of onset and clinical signs of pemphigus foliaceus in the horse and diagnostic tests used in these patients. Records of 13 horses with pemphigus foliaceus diagnosed by history, clinical signs, histopathology and exclusion of differential diagnoses were evaluated retrospectively. Breeds included six Quarterhorses, two American paint horses, two ponies, one Spanish mustang, one Arabian horse and one Warmblood horse. Six were mares, five geldings and two stallions. Three of the patients were foals younger than 6 months, nine were older horses over 9 years of age and one horse was 4 years old. Mean age was 9 years with a range from 3 months to 25 years. Crusting (11), scaling (10) and alopecia (9) were the most common lesions and were present most commonly on the face (9), neck (9) and trunk (9). Extremities were involved in eight of the horses. Pustules were seen in three horses. Pruritus was present in more than half of the patients (7). Acantholytic cells were identified in four of the six horses in which cytology was evaluated. Histopathology was supportive in all horses. Pemphigus foliaceus in the horse typically presents as a scaly or crusty skin disease in very young or older horses. Face, neck and trunk are most commonly affected. Cytology provides diagnostic clues in the majority of patients and is a useful diagnostic tool; histopathology confirms the diagnosis.

Pseudomonas otitis externa – therapeutic results using a new ear cleanser

*McKeever Dermatology Clinics
†Division of Respiratory Medicine, University of Nottingham, UK

This study investigated the novel two-part cleanser Sanova (Alcide Corp., Redmond, WA) for the treatment of chronic, Pseudomonas aeruginosa otitis externa in dogs that had been referred to a veterinary dermatology clinic for refractory otitis. These dogs had no other organisms isolated on qualitative culture and had intact tympanic membranes. The cleanser consisted of a base solution of 2400 p.p.m. sodium chlorite and an activator of 1.2% citric acid. These were mixed in a 1 : 1 ratio just prior to use, liberating free chlorine ions. Objective quantitative cultures and subjective clinical scoring were used to evaluate the efficacy of the treatment in 19 dogs with a total of 27 otic ears. The use of other medications and cleansers were prohibited throughout the 14-day study. Other alternative treatments were not compared. For humanitarian reasons, all dogs were treated. Controls were used to show that the quantitative culture sampling did not significantly effect subsequent measurements (P = 0.556). After 14 days of twice-daily treatment, subjective, clinical scores improved significantly (P < 0.0001). Quantitative cultures showed a significant decrease in viable organisms in the ears after the very first treatment (P < 0.0001) and after 14 days of twice-daily treatments (P = 0.0023). Nine of the 27 ears (33%) were culture negative after 14 days of treatment. The results of this study show that a two-part ear cleaner generating free chlorine ions is useful in the management of Pseudomonas otitis externa.

Funding provided by Alcide Corporation in the form of Sanova cleanser used in the study.

Quantity and distribution of Malassezia organisms on the skin of normal and feather-picking psittacines

*Veterinary Specialists of Alaska, Anchorage, Alaska, USA
†Department of Clinical Studies, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania, USA
‡Department of Clinical Sciences, Colorado State University, Ft. Collins, Colorado, USA
§Department of Pathobiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania, USA

Malassezia dermatitis has been implicated as a possible cause of feather picking in birds. No studies exist that have established the normal cutaneous microflora in birds. The purpose of this study was to determine if Malassezia organisms could be detected on the skin of normal and chronic feather-picking birds via tape cytology and culture. Samples from 103 psittacines (50 normal and 53 pickers) were obtained from the following six sites: head, neck, proventer, propatagium, and inguinal and preen gland area. Cytology was obtained using acetate tape, stained using a modified Wright's stain, and yeast in a 0.5 cm2 area were counted. Cultures were obtained using adhesive tape that was then applied to oil-enhanced Sabaroud's agar. Additionally, PCR using primers specific for the genus Malassezia spp., the species M. pachydermatis, saprophytic fungi and Candida albicans was performed on colonies believed to be yeast. Of the 618 sites sampled for cytology, yeast were found in only 61 samples (10%). Cultures from 30 different sites believed to be yeast or other fungal organisms were submitted for PCR. All were negative for Malassezia by PCR, although Candida albicans was confirmed on one sample. Fungal DNA was found in all other samples, and could have represented either other species of Candida, or fungi other than yeast. The number of yeast identified in normal vs. feather-picking psittacines via cytology was not statistically significant. In this study yeast were found infrequently on cytology in both normal and feather-picking birds.

This study was supported by a departmental research grant, University of Pennsylvania.

Recurrent cutaneous vasculitis in a dog putatively due to herbicide exposure

Allergy and Dermatology Clinic for Animals, Livonia, USA

Michigan State University, College of Veterinary Medicine, Department of Small Animal Clinical Sciences, Veterinary Medical Center, East Lansing, USA

Cutaneous vasculitis is an uncommon disease of dogs that is due to a type III hypersensitivity reaction. Clinically, purpura, ulcers, nodules or urticaria may be present. This is a case report of a dog with recurrent vasculitis putatively due to herbicide exposure. A 5-year-old, neutered male beagle dog was presented to the emergency clinic with pain and pruritus of 3 days’ duration. Allergies were diagnosed and amoxicillin/clavulanic acid and prednisone were dispensed. He was presented to the author the following day. Physical examination abnormalities were limited to the skin and included multifocal erythematous macules and purpura. Pending laboratory results, doxycycline and prednisolone were dispensed. Histopathological findings were consistent with neutrophilic vasculitis. Ten days later, all lesions had resolved and the prednisolone was tapered over a 3-month period. One year and 2 days later, the dog was re-presented with a history of pain and pruritus of 1 day's duration. Physical examination abnormalities were identical to the previous year's episode. Histopathological examination was consistent with neutrophilic vasculitis. Treatment with a 10-day course of prednisolone resolved the clinical signs. The owner reported that she had applied a herbicide to the yard prior to the onset of clinical signs both years. Timing, development and reproducibility of the clinical signs, and the course of the disease suggest that exposure to the herbicide was the probable cause of the cutaneous vasculitis. It was not possible to ascertain whether the vasculitis was due to percutaneous or systemic absorption.

The effect of body region on the canine hair cycle as defined by unit area trichogram

*Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Minnesota, Saint Paul, Minnesota, USA
†Pfizer Global Research and Development, Ann Arbor, Michigan, USA

The impact of anatomic location on trichogram analysis of the hair cycle phases was evaluated in 15 clinically normal dogs, represented by mixed breed (4); Labrador retriever (3); Golden retriever (2); German shepherd (2); Yorkshire terrier (1); Old English sheepdog (1); Coonhound (1) and Siberian husky (1). The purposes of this study were to determine if the number of hairs in anagen and telogen vary among anatomic sites within a dog and to see whether there is an optimal region to sample hairs for trichogram evaluation of the hair cycle. In each dog eight sites were sampled. Four (26.7%) dogs had no significant differences in the number of hairs in anagen and telogen among the eight body sites. Nine (81.8%) of the remaining 11 dogs had only one site with significant differences in the number of hairs in anagen or telogen. In seven (77.8%) of these dogs only the anagen differed significantly, and in two (22.2%) both phases differed significantly. Two (18.2%) dogs revealed two sites with significant differences in the number of hairs in anagen. The number of hairs in anagen and telogen in the shoulder area did not vary significantly in any of the 15 dogs. This observation, and the ease of sampling at this site, indicate that the shoulder is the site of choice when studying variations in ratios of hair cycle phases using unit area trichogram. Our results also suggest that numbers of telogen and anagen hairs from body regions with different hair shaft lengths do not vary significantly.

This project was funded by ‘College of Veterinary Medicine Small Companion Animal Grant’, University of Minnesota, Saint Paul, Minnesota.

The effects of a mock ultrasound procedure on cortisol concentrations during low dose dexamethasone suppression testing in normal adult dogs

Department of Small Animal Clinical Sciences, University of Tennessee, Knoxville, TN, USA

The objective of the study was to determine if the stress of an ultrasound procedure would interfere with the suppressive effect of dexamethasone in healthy dogs during low dose dexamethasone suppression testing (LDDST). Six clinically normal adult dogs had low dose dexamethasone suppression testing repeated weekly for 5 weeks. Serum samples were drawn at 2, 4, 6 and 8 h postdexamethasone injection. All dogs included in the study had cortisol concentrations that suppressed to < 35.9 nmol L−1 during the initial LDDST (week 1) at both the 4-h and 8-h sampling times. An abdominal ultrasound examination was reproduced on all dogs during the LDDST at randomized time points for weeks 2 to 5. In the second portion of the study, 4–16 weeks later, cortisol concentrations were measured prior to, and immediately following the mock ultrasound procedure. Statistical analysis was performed using SIGMASTAT® 2.0 for Windows (Chicago, IL, USA), with significance set at P < 0.05. No significant differences were detected when comparing median cortisol concentrations postmock ultrasound to nonmock ultrasound cortisol concentrations for each sampling time postdexamethasone injection. Median baseline cortisol concentrations were significantly greater than those at all time points postdexamethasone administration. In the second portion of the study (without dexamethasone), significant increases in cortisol concentrations were detected when measured immediately following the mock ultrasound procedure, thus confirming that a stressful event occurred. This study suggests that minor medical procedures performed during a LDDST do not alter the results in normal dogs.

This study was funded by the Department of Small Animal Clinical Sciences, University of Tennessee.

The prevalence of apoptotic keratinocytes in equine epidermis: a retrospective study of skin biopsy specimens from 254 horses with non-neoplastic dermatoses

K. D. MACLEOD*, D. W. SCOTT*, and H. N. ERB†
*Departments of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, USA
†Population Medicine, College of Veterinary Medicine, Cornell University, Ithaca, USA

A retrospective study was performed to assess the prevalence of apoptotic epidermal keratinocytes in biopsy specimens from 254 horses with non-neoplastic dermatoses. All biopsy specimens had been submitted to the Pathology Service at the College of Veterinary Medicine at Cornell University from 1972 to 1987, processed routinely for histopathological evaluation and stained with haematoxylin and eosin. In addition, 27 skin biopsy specimens taken from horses with normal skin that had been submitted to our necropsy service were also evaluated. One or more apoptotic keratinocytes were found in specimens from 30 of 254 horses (11.8% of total) with different dermatoses, and in 1 of 27 specimens (3.7%) from normal horses. Neither the number of apoptotic keratinocytes nor the level of the epidermis at which they occurred were different between various disease groupings. However, the prevalence of apoptotic keratinocytes in a group of erythema multiforme (EM), discoid erythematosus (DLE), systemic lupus erythematosus (SLE) and photodermatitis was significantly greater (52.4% of cases) than in a grouping of all other dermatoses (8.2%). There was no correlation between the number of apoptotic keratinocytes and the extent of epidermal hyperplasia and hyperkeratosis. In conclusion, apoptotic epidermal keratinocytes are an uncommon finding in biopsy specimens from horses with inflammatory dermatoses. The prevalence of apoptotic epidermal keratinocytes is significantly greater in EM, DLE, SLE and photodermatitis. The observation of apoptotic keratinocytes in equine histopathological specimens should prompt inclusion of these diseases in the differential diagnosis.

Transdermal delivery of Fluoxetine in cat skin using Franz diffusion chambers in vitro

*DermTech International, San Diego, CA, USA
†MacroChem Corp, Lexington, MA, USA

This study was designed to compare the topical pharmacokinetics of six formulations containing Fluoxetine in cat skin using the in vitro cadaver skin finite dose model. The test formulations contained 0 to 10% (w/w) 2-n-nonyl-1,3-dioxolane (SEPA®, MacroChem Corporation), a penetration enhancer, with and without propylene glycol (PG). Skin from three animals (upper dorsal back, parallel to spine), hair clipped to ∼2 mm, were mounted onto 0.8 cm2 Franz Diffusion Cells. The receptor fluid was phosphate buffered saline (PBS) + 0.1% Volpo (a nonionic surfactant), and the epidermal skin surface was left open to ambient conditions. Each formulation was tested in duplicate on skin from each animal at a dose of 5 µL/cell. The receptor fluid was sampled at 2, 4, 6, 8, 12, 24, 32 and 48 h after dosing. Quantification of Fluoxetine was by Positive-Ion Electrospray LC/MS. SEPA increased transdermal penetration of Fluoxetine over a 48-h period in a concentration-dependent manner. The addition of PG to the formulations led to a rapid initial peak flux at 4–5 h followed by a slow decline over 48 h. Formulations with no PG showed a steady rate of penetration between 8 and 48 h. Total penetration (0–48 h) ranged from a low of ∼5 to ∼45 µg (3–30% of the applied dose). Formulations containing 10% SEPA showed the highest drug penetration. This study also demonstrates the utility and value of using the Franz Diffusion Cell for assessing and comparing topical formulations in vitro before moving to live animal testing.

This study was funded by the MacroChem Corporation.