Verrucous pastern dermatitis syndrome in heavy draught horses. Part II: Clinical findings

In the present field study the skin of the feet of 37 heavy draught horses of different breeds showing verrucous pastern dermatitis was examined clinically. Included were the degree of severity of the disease and the prevalence of anatomically normal structures associated with the skin: fetlock tufts of hair ("feathering"), ergots, chestnuts, bulges in the pastern region, cannon circumference. Each horse was examined for Chorioptes sp. skin mites. Information was also collected on the development of the skin alterations and housing conditions and feeding. These individual data were correlated with the clinical degree of severity of verrucous pastern dermatitis, which was evaluated using a numerical code (scoring system). In addition, punch biopsies were taken from the diseased skin of the feet and from healthy skin of the neck for comparative patho-histological examination (see Part III). Verrucous pastern dermatitis is a chronic disease which can be divided into four groups: scaling (group I), hyperkeratotic and hyperplastic plaque-like lesions (group II), tuberous skin masses (group III), and verrucous skin lesions with rugged surfaces (group IV). No correlation was found between the clinical degree of severity of the skin lesions and sex, breed, amount of work, use of stallions for breeding, grooming condition of the hair, white markings in the foot region, or Chorioptes sp. infestation. In regard to feeding it was found that the amount of maize and oats fed had some influence on the clinical degree of severity. Statistical analysis revealed a significant correlation between the clinical degree of severity and the age, the grooming condition of the hooves, and the mean cannon circumference. The prevalence of fetlock tufts of hair, chestnuts, ergots, and anatomically normal bulges in the pastern region also increased significantly with the clinical degree of severity. Furthermore the study revealed that the clinical degree of severity depended on the hygienic conditions of the stables and of the ground where the horses were kept outdoors.     

A case of superficial suppurative necrolytic dermatitis of miniature schnauzers with identification of a causative agent using patch testing

A 9‐year‐old, castrated male, miniature schnauzer presented with malaise, anorexia, fever and severe inflammatory skin lesions on the dorsum, thighs and pinnae. The lesions developed 2 days after bathing with a commercial shampoo. Histopathological examination of skin samples revealed neutrophilic exocytosis, parakeratosis, epidermal hyperplasia and neutrophilic infiltration in the superficial dermis. Skin lesions resolved completely after 14 days of treatment with prednisolone and ofloxacin. Patch testing performed on the patient and a clinically healthy dog showed erythema at the site exposed to the culprit shampoo 48 h later only on the patient. Histopathological findings of the erythematous reaction were similar to those of the spontaneous skin lesions. Based on these findings, the dog was diagnosed with superficial suppurative necrolytic dermatitis of miniature schnauzers. The patch test results suggested that contact dermatitis to a commercial shampoo played a role in the pathogenesis of this disease.     

Up-regulation of cytokeratin expression in canine distemper virus-infected canine footpad epidermis

Cytokeratin expression was assessed in footpad epidermis from dogs using immunohistochemistry. Four groups of dogs were studied: dogs with experimentally induced distemper and with canine distemper virus (CDV) in footpad epidermis (group 1, n = 7); dogs with experimentally induced distemper and without CDV in footpad epidermis (group 2, n = 4); inoculated dogs without distemper and without CDV in the footpad epidermis (group 3, n = 8), and noninoculated dogs without distemper (group 4, n = 2). No increase in thickness of the footpad epidermis was present in any of these groups. Sections of metacarpal or metatarsal pads were stained for cytokeratin (CK)14 (proliferation-associated), CK10 (correlated with early differentiation), and for involucrin (associated with terminal differentiation). CK14 was present in basal keratinocytes of all groups, but staining intensity decreased towards the corneal layer in groups 2-4, but not in group 1. CK10 was present in the spinous and granular layer of all groups, but staining of the granular layer was much stronger in group 1. Involucrin was present in the granular layer of footpads of group 1 and only in the upper part of this layer in groups 2-4. The results demonstrate increased staining intensity and/or wider distribution within the footpad epidermis in group 1 dogs when compared to the other groups. This was interpreted as up-regulation in expression of these proteins. These findings suggest that presence of CDV antigen and mRNA in footpad epidermis was associated with an increase in expression of CK14, CK10 and involucrin. The potential role of this up-regulation in cytokeratin expression in the development of CDV-induced digital hyperkeratosis remains speculative at the moment and requires further studies.     

Cellular immunophenotyping of exfoliative dermatitis in canine leishmaniosis (Leishmania infantum)

Lymphocyte subsets, major histocompatibility complex (MHC)-II expressing cells and number of amastigotes in the epidermis and dermis were investigated immunohistochemically in 48 dogs with patent leishmaniosis, with or without exfoliative dermatitis (ED) to study the immunopathogenesis of this common cutaneous form of the disease. Skin biopsies were obtained and compared for ED sites (group A, n = 26), normal-appearing skin from the same animals (group B, n = 24), and leishmanial dogs not exhibiting ED (group C, n = 22), and normal controls (group D, n = 22). The CD3+, CD45RA+, CD4+, CD8+ (CD8a+), CD21+, and MHC-II+ cells and leishmania amastigotes were identified immunohistochemically and counted with the aid of an image analysis system. Pyogranulomatous to granulomatous dermatitis, expressed in various histopathological patterns, was noticed in all groups A and B and in half of group C dogs. In the epidermis, the low number of T-cells and their subsets did not differ significantly between groups A and B, but CD8+ outnumbered CD4+ lymphocytes in both groups. MHC-II+ expression on epidermal keratinocytes was intense in the skin with and without lesions from dogs with ED but not in group C dogs. CD3+, CD8+ and MHC-II+ cells were fewer in group C compared to group A and B dogs. In the dermis, CD3+ cells in group A animals were mainly represented by the CD8+. CD45RA+ and CD21+ cells were also seen in high numbers. MHC-II expression, potentially in lymphocytes, fibroblasts, dendritic cells, and macrophages was intense. The numbers of all cellular subpopulations in the dermis were significantly different between the groups, being highest in group A and lowest in group D. In sebaceous adenitis sites, CD4+ outnumbered CD8+ cells in contrast to the neighbouring dermis and the epidermis. The number of CD21+ and CD45RA+ cells was much lower in the inflamed sebaceous glands compared to the dermis. Finally, the number of amastigotes in the normal-appearing skin was significantly higher in the ED dogs (group B) than in those not exhibiting this cutaneous form of the disease (group C).     

Pilot investigation of a model for canine atopic dermatitis: environmental house dust mite challenge of high-IgE-producing beagles, mite hypersensitive dogs with atopic dermatitis and normal dogs

Although canine atopic dermatitis (cAD) is common, few models are available. The aim of this study was to evaluate high-IgE beagles epicutaneously sensitized to house dust mite (HDM) as a possible model for cAD. Six high-IgE beagles were environmentally challenged with HDM using various doses and protocols. Similar challenge protocols were used in positive and negative control dogs: three dogs with naturally occurring cAD and positive intradermal skin test (IDT) to HDM and three normal dogs without history of skin disease and negative IDT to HDM. All high-IgE beagles and all atopic dogs developed severe cutaneous lesions and pruritus after challenge. Lesions were erythematous papules and macules in contact areas such as face, ears, ventral abdomen, groin, axillae and feet. They were first visible after 6 h and increased in severity over time. No normal dog developed pruritus or lesions. Biopsies of representative lesions in the high-IgE beagles were taken for histopathology and immunohistochemistry. There was superficial perivascular dermatitis with mononuclear infiltrates and spongiosis. Lymphocytes and eosinophils accumulated in small epidermal micro-abscesses with hyperplasia of epidermal IgE-bearing dendritic cells. These findings suggest that this colony of high-IgE beagles develops a dermatitis that clinically, histopathologically and immunologically resembles the naturally occurring canine disease. It is also concluded that this modality of challenge is not irritating to normal dogs but induces flare-ups in hypersensitive atopic dogs.     

Adenomatous hyperplasia of the thyroid gland in beluga whales (Delphinapterus leucas) from the St. Lawrence Estuary and Hudson Bay, Quebec, Canada

We evaluated thyroid gland lesions in beluga whales (Delphinapterus leucas) from the St. Lawrence Estuary (n = 16) and Hudson Bay (n = 14). Follicular cysts and nodules of adenomatous hyperplasia of the thyroid gland were found in eight and nine adults from the St. Lawrence Estuary (n = 10), respectively, and in four and six adults from Hudson Bay (n = 14), respectively. The total volume of the lesions of thyroid adenomatous hyperplasia was positively correlated with age in both populations. Comparison between populations could not be performed because of differences in age structures of sample groups. Beluga whales from both populations have unique thyroid lesions among marine mammals.     

Experimental Transmission of Discrete Epidermal Hyperplasia in Walleyes

Abstract

Two related retroviruses, designated walleye epidermal hyperplasia virus type 1 (WEHV1) and type 2 (WEHV2), have been identified in discrete epidermal hyperplasia skin lesions from adult walleyes Stizostedion vitreum. A transmission experiment was conducted in an effort to provide evidence for a viral etiology and to develop a model for pathogenesis studies. Cell-free filtrates derived from discrete epidermal hyperplasia lesions and known to harbor WEHV1 and WEHV2 were injected into young-of-the-year (age-0) walleyes. Discrete epidermal hyperplasia developed in 97% of walleyes inoculated with lesion filtrates; whereas those injected with a cell-free filtrate of normal walleye skin did not develop lesions. The presence of WEHV1 or WEHV2 was detected by polymerase chain reaction (PCR) assay. Amplified DNA products from the PCR assays indicated the presence of viral sequences in 100% and 69% of the skin lesions for WEHV2 and WEHV1, respectively.     

Experimental copper deficiency, chromium deficiency and additional molybdenum supplementation in goats--pathological findings

Secondary copper (Cu) deficiency, chromium (Cr) deficiency and molybdenosis (Mo) has been suggested to cause the "mysterious" moose disease in the southwest of Sweden. The present experiment was performed on goats to investigate the clinical, chemical, and pathological alterations after 20 months feeding of a semi-synthetic diet deficient in Cu and Cr. Four groups were included in the study: control group (n = 4), Cu-deficient group (group 1, n = 4), Cr-deficient group (group 2, n = 2) and Cu + Cr-deficient group (group 3, n = 3). Group 3 was additionally supplemented with tetrathiomolybdate during the last 2 months of the experiment. Main histopathological findings in groups 1 and 3 were the lesions in the liver, characterised by a severe active fibrosis, bile duct proliferation, haemosiderosis and mild necroses. Additionally, degenerative alterations of the exocrine pancreas were prominent in groups 1 and 3. Lesions in group 3 were more pronounced than in group 1. In group 3, the skin showed an atrophic dermatosis, while in group 2 a crusty dermatitis caused by Candida spp. was observed. This study shows that liver, pancreas and skin are mainly affected by a long term deficiency of copper and the findings are complicated by molybdenum application while chromium deficiency produced no histomorphological effects in our study.     

Correlation of histologic and immunologic findings in cats with miliary dermatitis

Eighteen cats with miliary dermatitis were evaluated, using skin testing and histology. Sixteen cats had allergic skin disease (14 cats had positive skin-test reactions to flea antigen [two of which were also atopic], one was atopic only, and one was allergic to beef). In the two remaining cats, the cause of miliary dermatitis was not identified. Histologically, 17 of the cats had superficial eosinophilic dermatitis and epidermal spongiosis, crusting, and ulceration, which were compatible with an allergic cause. Four of these cats had concurrent eosinophilic plaques, which histologically resembled miliary lesions. This overlap of plaques with miliary lesions indicated that when plaques and miliary dermatitis are found concurrently, both lesions may be caused by the same allergens.     

Concentrations of thyroxine, beta carotene, vitamin A and pregnancy in heifers after administration of beta carotene

Serum concentrations of thyroxine (T4), beta-carotene (beta K), vitamin A and conception after the first insemination on the zero, sixth and 21st day were studied in 63 heifers fed synthetic beta K supplement in groups I to IV at stanchion housing and low-carotene diet. The following amount of beta K was supplemented per head/day: I--0 mg (control, n = 17), II--100 mg (n = 16), III--200 mg (n = 14) and IV--400 mg (n = 16). The parameters were evaluated separately according to groups and conception. By comparing the T4 concentration between experimental groups and control, separately in non-gravid and gravid animals, a significant increase (P less than 0.05) was determined only on the zero day in the fourth group. At the same time, in the fourth group, in comparison with the others, insignificantly lower T4 values were recorded in non-gravid animals. beta K values on the zero day in gravid animals increased in a direct proportion to the higher supplement (P less than 0.05; P less than 0.01; P less than 0.001); in non-gravid animals the increase was slower (P less than 0.05; P less than 0.05; P less than 0.01), but differences in relation to gravidity were not significant. An increase of beta K had no significant effect on serum concentrations of vitamin A. Differences between groups as far as conception was concerned were insignificant. It follows from the results that increasing rates of beta K, with the exception of serum concentrations, had no significant effect on other parameters. Higher concentrations of T4 and a slower increase of beta K in non-gravid animals, however, point at mutual co-operation relation and its positive effect on conception in animals.     

The development of verrucous pastern dermatitis syndrome in heavy draught horses. Part I: Review of the literature

Verrucous pastern dermatitis is a chronic hyperplastic dermatopathy of the feet of horses which is characterized by a greasy, odorous coating of the skin and, in advanced stages, by clearly demarcated calluses and wart-like proliferations. The disease occurs almost exclusively in cold-blooded and other heavy horses, with certain breeds affected most frequently. It is considered a distinct disease entity within the framework of pastern dermatitis syndrome. There is no consensus in the literature about relationship of the disease to the sex and age of the horse. Horses with a high cannon circumference and pronounced fetlock tufts of hair seem to be affected most severely. In chiefly anecdotal reports the cause of the disease or its aggravation has been ascribed to housing conditions and environmental influences, chemicals, mechanical insults, feeding, or infections with Chorioptes skin mites. It thus seems likely that the disease is affected by a variety of factors. Although verrucous pastern dermatitis has been known for hundreds of years, its etiology and pathogenesis remain unclear.     

Clinical course of digital dermatitis lesions in an endemically infected herd without preventive herd strategies

Lactating Holstein-Friesian dairy cows in four separately housed groups in a herd with endemic digital dermatitis (DD) were monitored weekly for 4 weeks in December 2004 for the presence of and transition between five stages (M0-M4) of DD. Cows were also monitored for the presence of heel horn erosion (HHE) and interdigital hyperplasia. Prior to the study, two groups had been housed indoors on a high or low energy ration, one group had been grazed and one was a dry cow group. All cows received the same ration during the period of investigation. 'Active infection' was defined as transition from M0, M1, M3 or M4 to M2 and 'resolving M2 lesions' were defined as transition from M2 to another stage. M2 lesions were diagnosed on 106 occasions in the hind claws of 49 (36%) of 138 dairy cows; both hind claws were affected in nine cases (18%). M2 lesions were more often painful on palpation than other stages; 94% of M2 lesions were located plantar-medially near the interdigital cleft and 71% had a diameter of 2-4 cm. More M1 lesions than other stages were found within the interdigital space. When interdigital hyperplasia was present, claws were always concurrently affected by DD. The baseline incidence for 'active infection' was 6% per week, increasing to 11% when HHE was present, 14% when cows were previously housed indoors and fed a high energy ration and 16% when cows were 60-120 days in lactation. Topical treatment with chlortetracycline resulted in resolution from M2 of 79% per week. There were no significant effects of group, stage of lactation, parity or HHE on resolution of M2 lesions.     

Poxvirus infection in a cat with presumptive human transmission

The present report describes a case of generalized cowpox virus infection with necrotizing facial dermatitis in a cat and a likely transmission to an animal keeper. The viral aetiology was confirmed by histopathology, immunohistochemistry, PCR, virus isolation, DNA sequencing and electron microscopy. Histopathological examination of the cat's skin revealed a severe, necrotizing dermatitis with ballooning degeneration and hyperplasia of epithelial cells with pathognomonic cytoplasmic eosinophilic inclusion bodies. Additionally, at post-mortem examination, a systemic poxvirus infection was detected affecting pancreas, thymus, lymph node, liver and lung. The human patient's skin biopsy revealed an ulcerative dermatitis with epidermal hyperplasia and ballooning degeneration. Serological investigation displayed a high orthopoxvirus-specific antibody titre in the human patient. Environmental factors increase the natural reservoir host population for cowpox viruses, such as voles, which results in a higher risk of infection for cats and subsequently for humans. Due to this zoonotic potential, a cowpox virus infection must be considered as an aetiological differential in cases of necrotizing dermatitis in cats.     

CT characteristics of primary hepatic mass lesions in dogs

Little information is available on the relationship between computed tomography (CT) imaging findings and the pathologic diagnosis of canine hepatic tumors. Our purpose was to clarify the characteristic features of CT findings in liver tumors in dogs. Data from 33 dogs with either a hepatocellular carcinoma, n = 14, hepatocellular adenoma, n = 14, or nodular hyperplasia, n = 5 were summarized from medical records. CT features for each histologic diagnosis were characterized and analyzed statistically. Common findings in hepatocellular carcinoma included central (79%, P = 0.0030) and marginal enhancement (93%, P = 0.00043) in the arterial phase, cyst-like lesions (93%), capsule formation (93%), and hypoattenuation in the portal (86%), and equilibrium phases (93%). Hepatic adenoma was characterized by a characteristic diffuse enhancement pattern during the arterial phase (57%, P = 0.013), which was also found in nodular hyperplasia (60%), but never in hepatocellular carcinoma. Nodular hyperplasia was less likely to have a capsule structure (20%, P = 0.0087). Mass size was significantly smaller in nodular hyperplasia than in hepatocellular carcinoma and hepatic adenoma (P = 0.0033 and 0.038, respectively). Hyperattenuation in the arterial and the portal phase i.e. contrast retention, was more frequent in hepatic adenoma than in the other groups (P = 0.037 and 0.037, respectively). Nodular hyperplasia was more frequently isoattenuating in the equilibrium phase (P = 0.043).     

Hereditary nasal parakeratosis in Labrador Retrievers

Hereditary nasal dermatitis is reported in 14 Labrador Retrievers and 4 Labrador Retriever crosses. This appears to be a newly described inherited disorder for which an autosomal recessive mode of inheritance is suspected. The lesions were first noted between 6 and 12 months of age. Histopathological analysis revealed parakeratotic hyperkeratosis, often with marked multifocal accumulation of proteinaceous fluid between keratinocytes within the stratum corneum and superficial stratum spinosum. There was also a sub-basal lymphoplasmacytic infiltration within the superficial dermis. Immunohistochemistry staining for IgG (n = 4), distemper and papillomaviruses (n = 4) were negative, as were serum antinuclear antibody serology (n = 4) and fungal culture (n = 7). Electron microscopy revealed an altered cornification process: retention of nuclear chromatin, absence of lamellar bodies and marked intercellular oedema. Dogs did not respond to oral administration of zinc methionin (n = 3), cephalexin (n = 4), vitamin A alcohol (n = 1) or topical tretinoin (n = 1). Improvement of the lesions was obtained with topical vitamin E (n = 2), petroleum jelly (n = 2), and propylene glycol (n = 5).     

Spontaneous Glomerular and Tubulointerstitial Lesions in Common Marmosets (Callithrix jacchus)

Spontaneous progressive nephropathy dominated by glomerular lesions in common marmosets has been reported. However, the histopathologic characteristics, including the relationship between glomerular and tubulointerstitial lesions, have not been described in detail. In the present study, the authors examined the histopathologic characteristics of the background renal lesions in common marmosets (3 males and 9 females, 3 to 8 years old). The severity of glomerular lesions was graded into 3 classes: grade I, no alteration; grade II, hilar/focal increase of mesangial matrix; grade III, global/diffuse increase of mesangial matrix. Tubulointerstitial lesions (tubular regeneration and hyperplasia and interstitial inflammation and fibrosis) were scored according to the area of each lesion. The renal lesions were characterized by enlargement of glomeruli, expanded mesangial area with increase of periodic acid-Schiff reaction-positive matrix, tubular regeneration and hyperplasia, and interstitial inflammation and fibrosis. Glomerular lesions progressed with increasing mesangial matrix and aging. Additionally, the tubulointerstitial lesions became exacerbated with progressing glomerular lesions. Tubular hyperplasia was divided into 4 types according to the structure of the cell layer (simple or stratified-like), the area of increased lining cells (partial or entire), cytoplasmic staining (eosinophilic or basophilic), brush border and thickness of basement membrane, and the activity of cell proliferation. In conclusion, the background renal lesions in common marmosets were characterized by glomerular lesions with increase of mesangial matrix, which progressed with aging, and secondary tubulointerstitial lesions, including tubular hyperplasia. Those lesions were thus diagnosed as progressive glomerulonephropathy in common marmosets.     

Measurement of serum immunoglobulin E (IgE) specific for house dust mite antigens in normal cats and cats with allergic skin disease

The purpose of this study was to determine whether cats with allergic skin disease have significant concentrations of serum Immunoglobulin E (IgE) specific for antigens derived from the house dust mites (HDM) Dermatophagoides farinae (DF) and Dermatophagoides pteronyssinus (DP). Enzyme-linked immunosorbent assays (ELISA) were developed for this purpose. Binding of serum allergen-specific IgE was detected via the use of biotinylated Fc-epsilon receptor alpha chain protein (FcvarepsilonRIalpha). Following optimisation of the assay, serum samples from 59 cats with allergic skin disease and 54 clinically normal cats were screened. Results were expressed as ELISA units per ml (EU/ml) compared to a standard curve. Serological findings were correlated with the clinical presentation of affected cats. Cats with symptoms of feline allergic skin disease were grouped as follows: self-induced alopecia without lesions (group 1), papulocrusting dermatitis (group 2), eosinophilic granuloma complex (group 3), papular/ulcerative dermatitis of head and neck/facial dermatitis (group 4), and a combination of symptoms (group 5). Control normal cats comprised the final group (group 6). The Kruskal-Wallis test was used for statistical analysis. There was no significant difference between groups for DF- and DP-specific IgE concentrations with a p-value of 0.875 and 0.705, respectively. Although the FcvarepsilonRIalpha-based ELISA was able to detect house dust mite-specific feline IgE, the presence of this allergen-specific IgE correlates poorly with the presence of clinical manifestations of allergic skin disease. The results of this study question the clinical relevance of house dust mite-specific IgE in feline allergic skin disease.