Alopecia areata (pelade) in a cow

A case of alopecia areata (pelade) is described in a cow. Alopecia areata is a rare idiopathic dermatosis of cattle. It is characterized by asymptomatic, solitary or multiple, annular areas of noninflammatory alopecia. Scrapings and cultures are negative, and the diagnosis is confirmed by skin biopsies taken from early lesions, which reveal accumulations of lymphocytes around the bulbs of anagen hair follicles. There is no known effective and practical treatment for affected cattle. The dermatitis is a cosmetic problem, but does not seem to affect general health and production, and spontaneous remission may occur.     

Alopecia areata in Eringer cows

Alopecia areata is a hair loss disorder in humans, dogs and horses with a suspected autoimmune aetiology targeting anagen hair follicles. Alopecia areata is only sporadically reported in cows. Recently, we observed several cases of suspected alopecia areata in Eringer cows. The aim of this study was to confirm the presumptive diagnosis of alopecia areata and to define the clinical phenotype and histopathological patterns, including characterization of the infiltrating inflammatory cells. Twenty Eringer cows with alopecia and 11 Eringer cows without skin problems were included in this study. Affected cows had either generalized or multifocal alopecia or hypotrichosis. The tail, forehead and distal extremities were usually spared. Punch biopsies were obtained from the centre and margin of alopecic lesions and normal haired skin. Histological examination revealed several alterations in anagen hair bulbs. These included peri‐ and intrabulbar lymphocytic infiltration, peribulbar fibrosis, degenerate matrix cells with clumped melanosomes and pigmentary incontinence. Mild lymphocytic infiltrative mural folliculitis was seen in the inferior segment and isthmus of the hair follicles. Hair shafts were often unpigmented and dysplastic. The large majority of infiltrating lymphocytes were CD3⁺ T cells, whereas only occasional CD20⁺ lymphocytes were present in the peribulbar infiltrate. Our findings confirm the diagnosis of T‐cell‐mediated alopecia areata in these cows. Alopecia areata appears to occur with increased frequency in the Eringer breed, but distinct predisposing factors could not be identified.     

A case of feline paraneoplastic alopecia with secondary Malossezia-associated dermatitis

A 13-year-old neutered female domestic shorthaired cat had progressive ventral abdominal alopecia attributed initially to hyperthyroidism. Corrective treatment by unilateral thyroidectomy did not, however, resolve the dermatosis and the alopecia progressed to involve the whole ventral trunk, the lower limbs and the head. Pruritus of the lower limbs was a prominent feature and was associated with the finding of Malassezia on cytology; Malassezia -associated dermatitis was diagnosed. Resolution of pruritus was seen after treatment with oral ketoconazole and a cleansing shampoo to eliminate the yeast, but severe polyphagia, small intestinal diarrhoea and polydipsia developed subsequently and the cat was euthanased. Necropsy revealed an exocrine pancreatic adenocarcinoma with hepatic metastases. The pancreatic, hepatic and dermatologlcal lesions were found to be typical of feline paraneoplastic alopecia (FPA). Malassezia -associated dermatitis can be associated with pruritus in cats with FPA.     

Alopecia areata with lymphocytic mural folliculitis affecting the isthmus in a thoroughbred mare

A 13-year-old, thoroughbred mare was presented with an 8-year history of multifocal, generalized, noninflammatory alopecia and a 3-month history of alopecia, erythema and scaling of the white star on the forehead and muzzle. Histopathological examination of biopsy samples from multiple sites on the body (mane, neck, shoulder, flank and gluteal region) showed a subtle lymphocytic inflammatory infiltrate affecting and surrounding the anagen hair bulbs, consistent with a diagnosis of alopecia areata. The biopsy sample from the star on the forehead showed atrophic hair follicles with perifollicular and mural mononuclear folliculitis affecting the isthmus. Immunohistochemical staining with a CD3 marker confirmed the T-lymphocytic origin of the inflammatory infiltrate in all the samples. The concurrent presence of lymphocytic infiltration at the bulbar and isthmic level of the hair follicles in the same horse is unusual. This finding may represent a variation of the histological appearance of alopecia areata.     

Morphologic and immunologic characterization of a canine isthmus mural folliculitis resembling pseudopelade of humans

The clinical, histopathologic and immunopathologic features of a novel form of isthmus mural folliculitis in dogs, which resembles pseudopelade in humans, were characterized. Clinically, dogs exhibited variably distributed foci of alopecia that persisted without treatment or did not respond to immunosuppressive therapy. Histopathologically, mixed mononuclear cell infiltrates, largely lymphocytes, infiltrated the follicular isthmus. Occasionally, inflammation extended above and below the follicular isthmus but did not involve the hair bulb or the epidermis. Severe follicular atrophy and variable atrophy of sebaceous glands occurred in all dogs. Folliculotropic lymphocytes exhibited most commonly CD3 and CD8 (cytotoxic T cells). Autoantibodies specific for the lower hair follicle were detected in the serum of affected patients. Western immunoblotting demonstrated binding of these antibodies to multiple follicular keratinocyte proteins, including hair keratins and trichohyalin. Lack of hair regrowth (in contrast to canine alopecia areata), as well as location of inflammation and extreme atrophy of adnexal units are similar to findings seen in human pseudopelade.     

Putative Malassezia dermatitis in six goats

Histopathology submissions from 28 goats with dermatological disease were identified in an archival search of pathology files. Microscopic sections of skin biopsy specimens were examined for the presence of Malassezia spp. organisms. Six cases with many Malassezia yeasts were identified histopathologically. Based on the extent of clinical disease, three cases were regarded as localized and three were generalized infections. Clinical findings included alopecia with dry seborrhoea (four cases), greasy seborrhoea (one case), and no clinical findings specific to localized Malassezia infection when concurrent bacterial infection was present (one case). Mild pruritus was reported in two cases of generalized infection. No breed predilection was apparent. Three cases were male and three were female. Malassezia dermatitis occurred in goats from 10 months to 13 years of age. Three of six cases had concurrent bacterial infection. Skin lesions resolved following topical antifungal therapy in the two goats that were treated. Histopathological findings in all cases were severe follicular and epidermal orthokeratotic hyperkeratosis with minimal epithelial change and mild superficial perivascular to interstitial nonsuppurative inflammation. Numerous budding yeasts were visible within the stratum corneum of all cases; however, Malassezia was not isolated in the three cases in which culture was attempted. Based upon these findings, the authors suggest that the diagnosis Malassezia dermatitis in goats is most likely to be made by cytological examination of skin impressions or by examination of skin biopsy samples.     

Oestrogen receptor evaluation in Pomeranian dogs with hair cycle arrest (alopecia X) on melatonin supplementation

The role of oestrogen receptors in dogs with hair cycle arrest (alopecia X) was investigated by immunohistochemistry. The purpose of this study was to determine if hair regrowth in dogs with hair cycle arrest treated with melatonin was associated with a decrease in follicular oestrogen receptors. Fifteen Pomeranians (excluding intact females) with hair cycle arrest were enrolled. Two biopsies were obtained from alopecic areas of the trunk before and after 3 months on melatonin. Haematoxylin and eosin-stained tissues were examined and oestrogen receptor-alpha was demonstrated immunohistochemically. Common histopathological findings included hyperkeratosis, follicular keratosis, excessive tricholemmal keratinization (flame follicles), thin epidermis, few small anagen bulbs, epidermal pigmentation and melanin aggregates within follicular keratin. Melanin aggregates within basal cells and hair were an occasional finding. After 3 months, 40% (six) dogs had mild to moderate hair regrowth. Biopsies from six dogs showed histological evidence of an increase in anagen hairs and eight dogs had a decrease in epidermal pigmentation. Moderate to marked staining intensity of oestrogen receptor-alpha was noted in all sebaceous gland basal cells, all small hair bulbs and follicular epithelium of telogen hairs. There was no oestrogen receptor-alpha staining of nuclei within the epidermis, apocrine glands or dermal fibroblasts. Large anagen hair bulbs had minimal to no oestrogen receptor staining. Hair regrowth was not associated with a change in oestrogen receptor-alpha staining.     

Mycologic disorders of the skin

Cutaneous tissue can become infected when fungal organisms contaminate or colonize the epidermal surface or hair follicles. The skin can be a portal of entry for fungal infection when the epithelial barrier is breached or it can be a site for disseminated, systemic fungal disease. The two most common cutaneous fungal infections in small animals are dermatophytosis and Malassezia dermatitis. Dermatophytosis is a superficial cutaneous infection with one or more of the fungal species in the keratinophilic genera Microsporum, Trichophyton, or Epidermophyton. Malassezia pachydermatis is a nonlipid dependent fungal species that is a normal commensal inhabitant of the skin and external ear canal in dogs and cats. Malassezia pachydermatis is the most common cause of Malassezia dermatitis. The diagnosis and treatment of these cutaneous fungal infections will be discussed.     

Malassezia slooffiae-associated dermatitis in a goat

An adult male Pygmy goat with a history of losing hair and declining body condition was euthanized, and a complete diagnostic work-up was performed. The animal showed diffuse alopecia on the dorsal and lateral sides of thorax and abdomen, proximal legs, neck and face. Histology revealed diffuse orthokeratotic hyperkeratosis, epidermal hyperplasia and perivascular dermatitis. Broad-based budding yeasts and hyphae were visible in the keratin layer. Malassezia slooffiae was identified in the skin by polymerase chain reaction amplification of part of the large subunit rRNA gene using broad-range fungal primers and DNA sequencing. This is the first report of M. slooffiae-associated dermatitis in goats.     

Anti‐isthmus autoimmunity in a novel feline acquired alopecia resembling pseudopelade of humans*

Pseudopelade is a primary scarring (cicatricial) alopecia of humans characterized by lymphocyte‐rich inflammation centred around the hair follicle isthmus. Lymphocyte folliculotropism is associated with isthmus apoptosis and, ultimately, follicular destruction and dermal fibrosis. In a cat, an acquired alopecia was diagnosed as pseudopelade based on the following criteria: (i) an adult‐onset, patchy to diffuse nonpruritic hair loss; (ii) an early folliculo‐destructive phase in which lymphocytes and dendritic cells accumulated in and around the follicular isthmus; and (iii) a late stage in which the lower segments of hair follicles underwent atrophy and were replaced by fibrosing tracts. Additionally, immunological investigations characterized the cytotoxic phenotype of isthmotropic lymphocytes and demonstrated the presence of circulating IgG autoantibodies specific for multiple follicular antigens. Altogether, the results of the present study suggest an immune‐mediated pathogenesis for this case of feline pseudopelade, similarly to that causing alopecia areata in humans and other mammalian species.     

Diesel oil-induced alopecia in two cats

Two cats were presented for acute onset of rapidly progressive, bilaterally symmetrical hair loss of the ventrum and limbs. Alopecia occurred within 2 weeks after accidental skin exposure to diesel oil. The remaining hair epilated easily in affected areas. Denuded skin was strikingly dry and had adherent scale. Erythema and demarcation between affected and normal skin by a liquid-line were present in one case. Above this line, the hair could not be removed. The head and the footpads were not involved. Systemic signs were not observed. Both cats made a complete recovery without treatment. Histological examination in one cat revealed severe orthokeratotic hyperkeratosis, mild to moderate acanthosis, follicular keratosis, a moderate dermal infiltrate of mast cells and an almost complete absence of sebaceous glands. If skin contact with diesel oil occurs in a cat, thorough washing of skin and haircoat after soaking in prue vegetable oil is recommended.     

Symmetrical alopecia, scaling and hepatitis in a rabbit

A 5-year-old rabbit with inappetence, symmetrical alopecia and skin lesions was examined. No mites or Malassezia were found in skin scrapings and tape impressions and dermatophyte culture was negative. Trial therapy with ivermectin did not reduce skin lesion severity, and euthanasia was performed because of anorexia after 1 month. Histopathology of the skin showed hyperkeratosis, lymphocytic exocytosis, cell-poor interface dermatitis (lymphocytic infiltration and apoptotic cells in basal layer of epidermis), absence of sebaceous glands and lymphocytic mural folliculitis comparable to sebaceous adenitis and thymoma-associated exfoliative dermatitis previously described in rabbits. The liver exhibited an interface hepatitis, comparable to autoimmune hepatitis in man. The occurrence of morphological similarities to exfoliative dermatitis and sebaceous adenitis in rabbits, in association with an autoimmune hepatitis, has not been described before.     

Epidermal dysplasia and Malassezia infection in two West Highland White Terrier siblings: an inherited skin disorder or reaction to severe Malassezia infection?

Two 9-month-old West Highland White Terrier siblings were referred to our clinic with pruritus, alopecia and lichenification. Cytological examination of Scotch tape strippings revealed Malassezia organisms and cocci. Skin biopsy specimens showed epidermal dysplasia. Treatment included bathing with a 2% miconazole/chlorhexidine-containing shampoo, orally administered ketoconazole (5 mg kg-1, every 12 h) and cloxacillin (25 mg kg-1 every 8 h). Six weeks later, the dermal infection had resolved and there was hair regrowth. However, the dogs were still moderately pruritic. Intradermal allergy testing was positive for house dust mites, storage mites and Malassezia. Immunotherapy was initiated, and treatment with ketoconazole and cloxacillin was stopped. Skin biopsies, which were performed in both dogs 4 months after the first presentation, revealed mild superficial perivascular dermatitis. The remaining mild facial pruritus was easily controlled with topical treatment. These two cases indicate that epidermal dysplasia might be an inflammatory or hypersensitivity reaction to the Malassezia infection or a result of excessive self-trauma, rather than a congenital keratinization disorder.     

Retrospective study: the presence of Malassezia in feline skin biopsies. A clinicopathological study

Malassezia spp. dermatitis, a rare disorder in cats, has previously been associated with immune suppression and internal malignancies. This study evaluates the presence and importance of Malassezia spp. in feline biopsy specimens submitted for histopathological examination. Five hundred and fifty haematoxylin and eosin-stained skin biopsy specimens received for histopathological examination between January 1999 and November 2000 were reviewed. Fifteen (2.7%) submissions contained Malassezia organisms in the stratum corneum of the epidermis or follicular infundibulum. Eleven of 15 cats presented with an acute onset of multifocal to generalized skin lesions. All 11 cats were euthanized or died within 2 months of the onset of clinical signs. Seven cats had dermatopathological changes and clinical signs supportive of paraneoplastic alopecia, and three cats had an interface dermatitis suggestive of erythema multiforme or thymoma-associated dermatosis. Histopathological changes were nonspecific in one cat that was euthanized 2 weeks following onset of severe pruritus and alopecia. In three cats, Malassezia spp. were found in localized sites (two chin, one footpads) and appeared inconsequential to their overall health status. One cat had Malassezia spp. in association with cutaneous demodicosis. These findings suggest that Malassezia yeast in dermatopathological specimens from multifocal or generalized lesions should prompt a thorough clinical work-up for internal neoplasia.     

Macroscopic,cytological and bacteriological evaluation of anal sac content in normal dogs and in dogs with selected dermatological diseases

Abstract Macroscopic and cytological aspects of anal sac content were evaluated in 40 normal dogs and 10 dogs each with pyoderma, Malassezia dermatitis associated with atopic dermatitis and uncomplicated atopic dermatitis. Bacteria isolated from anal sacs were compared with those from abdominal skin and hair in 20 normal dogs and 10 dogs with pyoderma. There was no difference between the groups in anal sac dimension, or in the colour, consistency or presence of granules in their content. Extracellular bacteria were found in higher numbers in diseased animals, whereas intracellular bacteria were observed in 40% of dogs with pyoderma and in only 2.5% of normal dogs. Malassezia spp. were present in 15.7% of dogs, with no difference between groups. Neutrophils were observed in 12.5% of normal dogs, 30% of dogs with Malassezia dermatitis with underlying atopic dermatitis and in 70 and 80% of dogs with pyoderma and uncomplicated atopic dermatitis, respectively. Seven bacterial species were isolated from anal sacs, with no difference between normal dogs and dogs with pyoderma. In five normal animals and in four dogs with pyoderma the same bacterial strains were isolated from anal sacs and from abdominal skin and hair.     

Resolution of paraneoplastic alopecia following surgical removal of a pancreatic carcinoma in a cat

A 13-year-old female neutered domestic longhaired cat was presented with a five-month history of progressive weight loss and bilaterally symmetrical alopecia of the ventrum, limbs and perineum. The alopecic skin had a shiny appearance and hair in the non-alopecic areas was easily epilated. Fine needle aspirate cytology of a palpable cranial abdominal mass revealed it to be of epithelial or glandular origin. A pancreatic mass was excised by left pancreatectomy during exploratory laparotomy, and histopathology and skin biopsies confirmed a diagnosis of pancreatic carcinoma with concurrent paraneoplastic alopecia. No evidence of metastases was found on liver and lymph node biopsies. At re-examination 10 weeks after surgery, the hair had fully regrown. Skin signs recurred after 18 weeks and metastatic spread of the tumour was confirmed on postmortem examination. This case confirms that paraneoplastic alopecia associated with internal malignancies is a potentially reversible process if the internal neoplasm is excised.     

Malassezia dermatitis in the dog: a retrospective histopathological and immunopathological study of 86 cases (1990–95)

A retrospective histopathological and immunopathological study was conducted on 86 dogs with Malassezia dermatitis. West Highland White terriers, English Setters, Shih Tzus, Basset Hounds, American Cocker Spaniels, spayed females, and castrated males were found to be at increased risk. The histopathological reaction pattern of lymphocytic superficial perivascular to interstitial dermatitis with parakeratotic hyperkeratosis, irregular epidermal hyperplasia, diffuse intercellular oedema and lymphocytic exocytosis was found to be consistent with a diagnosis of Malassezia dermatitis whether yeast were histologically visible (73.3% of the cases) or not (26.7%). Immunopathological studies revealed that 60– > 90% of the inflammatory cells within the epidermis, and 25–75% of those within the dermis were CD3+T lymphocytes, and that the only immunoglobulin-positive cells were dermal plasma cells.     

P-89 Aeromonas hydrophila-associated skin lesions and septicaemia in a Nile crocodile

Mites are frequent agents of skin diseases in veterinary dermatology, particularly in rodents. The authors report an original case of infestation in two guinea pigs of the same household. Two adult guinea pigs were presented with a 3-month history of alopecia, matted hair, erythema, scales and mild pruritus. The first guinea pig showed almost complete truncal alopecia with mild scaling, whereas the other one had only recently developed mild alopecia of the abdomen and mild pruritus. Numerous live, long-legged mites were present both in adhesive tape and skin scrapings. Mycology (Wood's lamp and DTM agar culture) was negative. Histopathological examination of a skin biopsy did not reveal any significant inflammatory disease and morphological changes were limited to hair follicles in the telogen phase. Mites were identified as hypopodes of Acarus farris ( Acaridae ), but no adult stages were present. Hypopodes were also found in the hay. Control was obtained with acaricidal treatment with Phoxim 0.05% once weekly for 4 weeks, and the elimination of contaminated hay. The lesions and the alopecia resolved rapidly. Hypopodes are additional nymphal stages of some mites of the suborder Astigmata . They develop for dispersing or dormancy under disadvantageous conditions. They can be active or inert, and some can be phoretic on the skin surface or intrafollicular. Although nonparasitic, they may cause dermatitis. Acarus farris have been rarely mentioned in the literature as a cause of dermatitis. This condition could be underdiagnosed or misdiagnosed in veterinary dermatology.
Funding: Self-funded.     

Thymoma-associated exfoliative dermatitis in a rabbit

A 5-year-old rabbit with generalized scaling is presented. Multiple skin scrapings and acetate tape impressions were negative for mites and Malassezia. Culture for dermatophytes was also negative. Skin biopsies showed similarities with sebaceous adenitis described in rabbits (absence of sebaceous glands, perifollicular lymphocytic infiltrate at the level of the absent sebaceous glands, lymphocytic mural folliculitis, interface dermatitis). The owners refused any treatment and 2 months later the rabbit was euthanized due to anorexia. At necropsy a mass was found in the anterior mediastinum. Histopathology confirmed a diagnosis of thymoma. A possible paraneoplastic skin disease was suspected, based on similarities with thymoma-associated exfoliative dermatitis in cats.     

Congenital anemia, dyskeratosis, and progressive alopecia in Polled Hereford calves

A new syndrome of anemia, alopecia, and dyskeratosis was identified in Polled Hereford calves in this study. Cutaneous changes included hyperkeratosis and hair loss around the muzzle and ear margins, which progressed to a generalized alopecia and hyperkeratotic dermatitis. Histologically, orthokeratotic hyperkeratosis with dyskeratosis of epidermal and follicular keratinocytes was present. Alopecia was correlated with dyskeratosis of Huxley's layer and an increasing proportion of follicles in the telogen phase of the hair cycle. Dermatitis was characterized by a mild dermal mononuclear cell infiltrate and mild lymphocytic perivascular dermatitis. The anemia present at birth was nonprogressive and was classified as normochromic and normocytic to macrocytic. Reticulocytosis was absent, but bone marrow was markedly hyperplastic. Nuclear cytoplasmic asynchrony of the rubricyte and metarubricyte stages occurred in the bone marrow. Abnormal rubricyte nuclei and maturation arrest at the late rubricyte stage were common. Cytologic features of the erythroid series are similar to those of type I congenital dyserythropoietic anemia of human beings. Genealogic features suggest that this is a primary hereditary defect. The mode of inheritance, however, remains to be determined.