Lack of detectable equine herpesviruses 1 and 2 in paraffin-embedded specimens of equine sarcoidosis.

BACKGROUND: Equine sarcoidosis is a rare, multisystemic, noncaseating, granulomatous and lymphoplasmacytic disease of unknown etiology. A recent report described a horse with granulomatous skin disease displaying histologic, electron microscopic, and polymerase chain reaction (PCR) findings consistent with equine herpesvirus 2 (EHV-2). OBJECTIVE: To investigate the presence of EHV-2 and equine herpesvirus 1 (EHV-1) in 8 horses with sarcoidosis. ANIMALS: Eight horses with sarcoidosis, reported previously. METHODS: Retrospective study. PCR assays of the tissues were performed to detect DNA associated with EHV-1 and EHV-2. For both herpesviruses the target was their respective glycoprotein B gene. Positive controls consisted of DNA from viral cultures of culturettes from naturally occurring respiratory infections of EHV-1 and EHV-2. RESULTS: The PCR analyses for both equine herpesviruses' DNA were negative in all 8 horses. CONCLUSION: The failure to detect DNA from EHV-1 and EHV-2 in paraffin-embedded skin of these 8 horses does not discount EHV-1 or EHV-2 as causing some cases of ES, but lends support to the presumably multifactorial etiologic nature of the disease.

Clinical, morphological and immunohistochemical characterization of cutaneous lymphocytosis in 23 cats.

Clinical, morphological and immunohistochemical features of cutaneous lymphocytosis, an uncommon disease histologically resembling well-differentiated malignant lymphoma, were characterized in 23 cats. Clinical outcome was correlated with histomorphology and immunophenotype in an attempt to predict benign vs. malignant behaviour. The disease mainly affected older cats. Lesions were solitary in 61% of cats and often characterized by alopecia (73.9%), as well as erythema, scaling and ulceration. The lateral thorax was most commonly affected (43.5%). Pruritus was frequent (65.2%). Systemic signs included anorexia and weight loss. Morphologically, lesions were characterized by dermal infiltrations of well-differentiated CD3+ T-cells (100%) and aggregates of CD79+ B-cells (64.3%). Cutaneous lymphocytosis is slowly progressive and relatively benign, although in some cats systemic signs led to euthanasia. Four of 12 euthanized cats and one live cat also had lymphoid infiltrates in internal organs. Unfortunately, we were unable to predict clinical outcome by histological and immunohistochemical evaluations of skin lesions.

Rapid identification of tissue micro-organisms in skin biopsy specimens from domestic animals using polyclonal BCG antibody.

Immunostaining with polyclonal anti-Mycobacterium bovis (BCG) was evaluated as a single screening method for the histological identification of micro-organisms in skin biopsy specimens from various veterinary species. Confirmed archival cases infected with Mycobacteria, Nocardia, Actinobacillus, Actinomyces, Streptococcus/Staphylococcus, Dermatophilus, spirochetes, Blastomyces, Coccidioides, Cryptococcus, Histoplasma, dermatophytes, Malassezia, Sporothrix, Leishmania, Pythium, phaeohyphomycetes and Prototheca organisms were selected. A total of 70 skin biopsy specimens from the dog, cat, horse, ox and llama were evaluated. The anti-BCG immunostain labelled bacteria and fungi with high sensitivity and minimal background staining but did not label spirochetes and protozoa (Leishmania). Differences were not noted between veterinary species. The results indicate that immunostaining with polyclonal anti-BCG is a suitable screening technique for the rapid identification of most common bacterial and fungal organisms in paraffin-embedded specimens. Also, mycobacterial and nocardial organisms were identified more readily with the anti-BCG immunostain in comparison to the histochemical stains.

Thiopurine methyltransferase in red blood cells of dogs, cats, and horses.

Our objective was to determine if thiopurine methyltransferase (TPMT), the enzyme important in the metabolism of azathioprine in human beings, is detectable in red blood cell lysates (RBCL) of healthy dogs, cats, and horses. Values for TPMT activity were determined from blood collected from 20 healthy dogs, cats, and horses. The TPMT activity in each animal's RBCL was determined using a radioenzymatic end point involving TPMT-facilitated metabolism of 6-mercaptopurine to 6-methylmercaptopurine (6-MMP). One unit of TPMT activity represents the formation of 1 nmol of 6-MMP per milliliter of packed red blood cells per hour of incubation at 37 degrees C. TPMT activity in RBCL was detectable in all species, with mean RBC values +/- standard deviation of 17.9 +/- 3.79 U/mL in dogs; 2.76 +/- 0.70 U/mL in cats; and 2.185 +/- 0.36 U/mL in horses. Values for TPMT in the 3 species were significantly (P < .05) different from one another. TPMT values for dogs were significantly higher than the other species, and TPMT values for cats were significantly higher than those for horses. We conclude that RBCL TPMT values are measurable in dogs. cats, and horses and that dogs have higher values than cats or horses. These findings are consistent with the lower tolerance for azathioprine in cats as compared with dogs. It remains to be determined whether RBCL TPMT values in these species correlate with TPMT activity in the liver, where most of the metabolization of azathioprine is believed to occur.

The use of fluoroquinolones in veterinary dermatology.

The fluoroquinolones are a group of antibiotics with considerable application for use in veterinary dermatology. They are rapidly bactericidal against a wide variety of clinically important organisms including Staphylococcus intermedius and gram-negative enteric bacilli by virtue of interference with the supercoiling of bacterial chromosomal material. Their favourable pharmacokinetic features make them applicable in many animal species, and in a range of dose formulations. The only major clinical contraindication is that fluoroquinolones should not be given to young, rapidly growing dogs as they can induce a noninflammatory, erosive arthropathy. For many years the only veterinary-labelled fluoroquinolone available was enrofloxacin. The selection of a fluoroquinolone has become more complex now that there are more choices available. Orbifloxacin, difloxacin and marbofloxacin now join enrofloxacin on the veterinary market, although not all of these are licensed in every country. The use of fluoroquinolones in dermatology remains controversial. The authors recommend that fluoroquinolones be considered in circumstances where canine pyoderma has been refractory to appropriate 'first line' antibiotics. They are most useful in the management of recurrent pyoderma and in chronic, deep pyoderma with extensive scar tissue. In addition, fluouroquinolones frequently are the drugs of choice for canine ear infections caused by Pseudomonas aeruginosa.

Determination of skin concentrations of enrofloxacin in dogs with pyoderma.

OBJECTIVE: To compare serum and skin concentrations of enrofloxacin in dogs with pyoderma with those of clinically normal dogs and to evaluate concentrations in dogs with superficial versus deep pyoderma. ANIMALS: 16 clinically normal dogs and 16 dogs with pyoderma. PROCEDURE: Enrofloxacin (approx 5 mg/kg of body weight, PO) was administered daily to all dogs. Serum samples and skin biopsy specimens were obtained on day 1 at 3 hours after drug administration and on day 3 immediately before and 3 hours after drug administration. Samples and specimens were assayed by high-performance liquid chromatography. Morphometric analysis was performed on skin biopsy specimens to determine correlation between inflammatory cells and peak tissue enrofloxacin concentration on day 1. RESULTS: Morphometric analysis revealed high correlation between dermal inflammatory cell count and drug concentration in dogs with pyoderma. CONCLUSIONS: At mean dosage of 5 mg/kg once daily, enrofloxacin tissue concentrations were significantly greater in dogs with pyoderma at 3 hours after pill administration. Enrofloxacin tissue concentration on day 3 at 3 hours after pill administration was 12.4 times the 90% minimum inhibitory concentration of enrofloxacin for Staphylococcus intermedius. CLINICAL RELEVANCE: In dogs with pyoderma, therapeutic tissue concentrations of enrofloxacin are reached as early as 3 hours after drug administration.

Serum and skin IgA concentrations in normal and atopic dogs.

OBJECTIVE: To compare serum and skin surface IgA concentrations from atopic and normal dogs. PROCEDURE: IgA concentrations in sera and skin washings of 20 clinically normal dogs that had no history of pruritus or skin disease were compared to those obtained in 20 dogs with a diagnosis of atopy determined by history, clinical examination and positive intradermal skin test. RESULTS: There was no significantly difference in the mean serum IgA concentration in normal dogs (252 +/- 187 mg/L) versus atopic animals (314 +/- 327). When skin washings from all sites in both groups were compared, atopic dogs had significantly greater concentrations of IgA in their skin washings than normal dogs as evaluated by an enzyme-linked immunoassay (P < 0.001). However, there was no significant difference between the individual sites of the skin washings of atopic and normal dogs. CONCLUSION: IgA concentrations of skin washings in atopic dogs were greater than in normal dogs. Further investigations need to determine if the greater concentrations were caused by nonspecific inflammation or by secretion of allergen-specific IgA onto the skin surface.

Selected feline eosinophilic skin diseases.

Eosinophilic plaque and mosquito-bite dermatitis are recognized hypersensitivity reactions. The pathogenesis of eosinophilic granuloma and indolent ulcer are not as clearly understood. Each of these syndromes is distinctive from a clinical and histopathologic view point. Accurate diagnosis depends on history, physical findings, and histopathologic evaluation. Understanding of feline dermatology will be furthered by including these syndromes in a broader grouping that encompasses all the feline eosinophilic dermatoses.

Canine bullous pemphigoid (BP): identification of the 180-kd canine BP antigen by circulating autoantibodies.

Human bullous pemphigoid (BP) is an immune-mediated blistering disease characterized by autoantibodies against BP antigens (230/180 kd), which are constitutive glycoproteins of hemidesmosomes found in basal keratinocytes. Blistering diseases similar to human BP have been reported in dogs. IgG deposits at the basement membrane zone (BMZ) are a common feature of canine BP. Although circulating anti-BMZ IgG autoantibodies have been demonstrated in some cases of canine BP, the specific skin protein targeted by these autoantibodies has not been identified. In this study, we characterized the antigenic target of the autoantibodies in the serum from a 3-year-old castrated male Pit Bull Terrier with BP. Direct immunofluorescence of the patient's skin demonstrated IgG deposits at the dermal-epidermal junction. Indirect immunofluorescence demonstrated autoantibodies in the patient's serum that stained the epidermal roof of salt-split canine skin and left the dermal floor unstained. These serum autoantibodies did not stain normal intact dog skin but labeled intact bovine tongue. Direct immunoelectron microscopy of the dog's skin revealed IgG deposits within the hemidesmosomes of the basal keratinocytes. Western immunoblotting experiments showed that canine keratinocytes express both the 230-kd and 180-kd bullous pemphigoid antigens, and the autoantibodies from the patient's serum recognized the 180-kd bullous pemphigoid antigen in proteins extracted from canine and human keratinocytes. Canine BP has many parallel features with human BP including similar immune deposition of IgG within hemidesmosomes and a hemidesmosome-associated 180-kd glycoprotein target for circulating autoantibodies.

Superficial necrolytic dermatitis (necrolytic migratory erythema) in dogs.

Twenty-two dogs with superficial necrolytic dermatitis were evaluated prospectively, twenty-one of which had characteristic crusting lesions of the paw pads. Histologically, epidermal lesions included parakeratosis and laminar intracellular edema. The plasma amino acid concentrations of eight dogs were markedly depressed. Nine dogs had terminal diabetes mellitus. These clinical and morphologic findings were strikingly similar to those of necrolytic migratory erythema in human beings, the most common cause of which is hyperglucagonemia due to islet cell tumor of the pancreas. No pancreatic tumors were found in these dogs; plasma glucagon concentrations in the five dogs tested were normal. The serum alkaline phosphatase concentrations were elevated in all dogs. Severe vacuolar hepatopathy, suggesting metabolically or hormonally induced hepatic dysfunction, was found in 21 dogs at necropsy or by biopsy; one dog had ultrasonographic abnormalities of the liver. Histopathologically, severe vacuolar alteration resulted in parenchymal collapse and nodular regeneration, which grossly mimicked cirrhosis. Although the definitive metabolic stimulus was not discovered for the cutaneous and hepatic lesions, the similarity of the cutaneous and biochemical features of canine superficial necrolytic dermatitis to human necrolytic migratory erythema warrants further investigation into possible underlying pancreatic hormonal dysfunction.

Use of etretinate for treatment of primary keratinization disorders (idiopathic seborrhea) in cocker spaniels, west highland white terriers, and basset hounds.

An open clinical trial was used to evaluate the synthetic retinoid, etretinate, for treatment of idiopathic seborrhea in Cocker Spaniels, West Highland White Terriers, and Basset Hounds. Clinical and histologic improvement was seen in the Cocker Spaniels. Etretinate had no beneficial effect on the skin disease of the West Highland White Terriers or the Basset Hounds. Etretinate treatment did not alter the type or degree of otitis externa. Clinical side effects were minimal. Relevant laboratory abnormalities were not detected.

A retrospective clinicopathologic study of 212 dogs with cutaneous hemangiomas and hemangiosarcomas.

The relationship between skin pigmentation and piliation and the development of hemangiomas and hemangiosarcomas in the dermis and subcutaneous tissue was studied in 212 dogs. These 212 dogs had a combined total of 306 tumors; 38 of these 212 dogs had two or more of the same tumor in a different location or a combination of hemangioma and hemangiosarcoma. The average age of the dogs at the time of excision of these tumors was greater than 10 years. There was no sex predilection for the presence or absence of tumors. Cutaneous hemangiomas (73%) were more common than cutaneous hemangiosarcomas (27%). Hemangiomas had no predilection for dermis (51%) or subcutaneous tissue (47%), but hemangiosarcomas had a marked predilection for dermis (73%) over subcutaneous tissue (7%). Dogs with short hair coats and lightly pigmented skin had more hemangiomas and hemangiosarcomas of the dermis (65%) than did dogs with variable length hair coats and pigmentation (28%). Dogs with short hair coats and lightly pigmented skin had fewer hemangiomas and hemangiosarcomas of the subcutaneous tissue (10%) than did dogs with variable length hair coats and pigmentation (22%). Dogs with short hair coats and lightly pigmented skin also had more hemangiomas and hemangiosarcomas of ventral glabrous skin (65%) than did dogs with variable length hair coats and pigmentation (22%). In addition, there was no predilection of subcutaneous hemangiosarcoma for haired (33%) versus glabrous (33%) skin, but dermal hemangiosarcoma had a marked predilection for the glabrous skin (63%) when compared with haired skin (10%). The increased incidence of dermal hemangiomas and hemangiosarcomas in ventral glabrous skin suggests an association between solar radiation and the biologic properties of glabrous skin in the genesis of these tumors.

Synthetic retinoids in veterinary dermatology.

The synthetic retinoids, isotretinoin (Accutane) and etretinate (Tegison) are vitamin A analogs. They affect epithelial differentiation and thus have potential for therapy for disorders of epithelial maturation such as keratinization defects of cutaneous neoplasia. The pharmacology, indications for use, clinical experience, potential toxicities, and recommended monitoring of these drugs are discussed.

Regional distribution of ten common skin diseases in dogs.

We investigated the regional distributions of the most commonly diagnosed skin diseases in dogs from 17 North American veterinary teaching hospitals. Between January 1983 and December 1983, 11,456 diagnoses of skin disease were made. The 10 most common diagnoses were fleabite allergic dermatitis, skin cancer, pyoderma, seborrhea, allergy, demodectic acariasis (demodicosis), sarcoptic acariasis, immune-mediated skin disease, endocrine related skin disease, and acral lick dermatitis. Regional differences in the frequency of skin diseases were apparent. The northeast region had high frequencies of fleabite allergic dermatitis, allergy, and immune-mediated disease, and a low frequency of seborrhea. The midwest had a high frequency of seborrhea, and low frequencies of demodectic acariasis and allergy. In the plains region, low frequencies of fleabite allergic dermatitis, pyoderma, seborrhea, allergy, and demodectic acariasis were detected. In the west, the frequencies of fleabite allergic dermatitis, skin cancer, pyoderma, seborrhea, and acral lick dermatitis were high, whereas few dogs had allergic disease and sarcoptic acariasis. The southwest had high frequencies of fleabite allergic dermatitis and demodectic and sarcoptic acariasis. Fleabite allergic dermatitis, pyoderma, and demodectic and sarcoptic acariasis were frequently diagnosed in the southeast, but the number of dogs with seborrhea was low.

Cutaneous fungal flora in twenty horses free of skin or ocular disease.

The fungal flora of the hair and underlying skin from 2 sites was examined qualitatively in 20 horses free of skin or ocular disease. Fungi were isolated from both the hair and the underlying skin of all 20 horses. Twenty-two genera regarded commonly as saprophytes were identified and an additional 2 fungi resembled the perfect state of the cutaneous pathogenic genera Microsporum and Trichophyton. Cladosporium spp, Penicillium spp, and Rhizopus spp were the most frequently isolated saprophytes. In general, similar fungi were isolated from the hair and underlying skin, and differences were not noted in isolates from the saddle and rump regions.

Dermatosis associated with feeding generic dog food: 13 cases (1981-1982).

The records of 13 dogs with a crusting dermatosis of the mucocutaneous junctions, pressure points, and trunk were evaluated. All of the dogs had been fed corn- and wheat-based commercial dry dog foods that failed to meet the National Research Council's recommendations for balanced nutrition. The dermatosis in all 13 dogs resolved completely after the diet was changed to one that met the National Research Council's recommendations. The disease was similar to that which has previously been called canine dry pyoderma, but is now known to be a zinc-responsive dermatosis.

Circulating immune complex concentrations in selected cases of skin disease in dogs.

Serum samples from 25 clinically normal dogs and 137 base-line serum samples from dogs with skin disease were assayed blindly for presence of circulating immune complexes (CIC). The method used was a solid-phase C1q-binding enzyme-linked immunosorbent assay. This assay detected only IgG-containing CIC that were capable of binding C1q. Statistical analysis revealed that dogs with systemic lupus erythematosus, discoid lupus erythematosus, generalized demodicosis, and recurrent staphylococcal pyoderma had significantly higher mean CIC concentrations than did normal dogs. Dogs with other skin diseases had mean CIC concentrations indistinguishable from those of normal dogs. Presence of CIC in dogs with these dermatopathies may have pathogenetic significance or may be the result of the disease process. Further studies are necessary to define the antigens contained in the immune complexes and the importance of CIC in skin disease of dogs.

Histopathologic features of pyotraumatic dermatitis.

The skin of 17 dogs with pyotraumatic dermatitis was studied microscopically. Two patterns were seen. The first pattern was a superficial, ulcerative, inflammatory process of undetermined cause and pathogenesis. Current recommended treatment, which includes corticosteroids, was believed to be appropriate for such lesions. The second pattern, suppurative folliculitis, was considered to be localized pyoderma. Dogs with severe folliculitis were believed to represent those cases of pyotraumatic dermatitis in which the response to corticosteroid treatment has been poor. It was concluded that antibiotics should be used for treating pyotraumatic dermatitis with suppurative folliculitis, in lesions responding poorly to treatment with corticosteroids, or possibly in any severe lesion of pyotraumatic dermatitis, especially in Golden Retrievers and Saint Bernards.