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.     

Congenital alopecia in a Bichon Frise

A Bichon Frise pup had congenital alopecia. Histologic evaluation revealed the absence of hair follicles, arector pili muscles, sebaceous glands, and sweat glands. Unlike previously described cases of congenital ectodermal defect, this alopecia was not associated with any color pattern; the pup was white until it was 4 months old, at which time normal black and brown pigmentation developed independently of the alopecic pattern.     

Severe bilaterally symmetrical alopecia in a horse

A 9-year-old Tennessee Walking Horse gelding was presented for diagnosis of the cause of extensive alopecia. Complete hair loss was noted over the head, neck, shoulder, thigh, and proximal limbs, but the trunk, distal limbs, pelvic area, mane, and tail were unaffected. The alopecic areas were visually noninflammatory with no exudate or crust except on the shoulder and along the back, where multifocal patchy areas of alopecia with scales and crust were evident. The horse was slightly pruritic. Microscopically, the hair bulbs, inner and outer root sheaths of inferior segments, and perifollicular regions were infiltrated by small to moderate numbers of small lymphocytes. Similar inflammation was occasionally evident in isthmus follicular walls as well as some apocrine glands. No sebaceous glands were affected. Immunohistochemistry confirmed that the small lymphocytes were CD3(+) T lymphocytes. The epidermis from the skin with scale and crusts along the horse's back exhibited mild to moderate hyperplasia, mild lymphocytic exocytosis, mild eosinophilic dermatitis, and diffuse parakeratosis with numerous budding yeasts, consistent with Malassezia spp. The final disease diagnosis was made as alopecia areata with Malassezia dermatitis. Alopecia areata could be a contributing underlying factor for Malassezia dermatitis.     

Mutually-induced traumatic alopecia responsive to husbandry modification in two cohabiting donkeys

Cutaneous expression of behavioural processes remains unexplored in donkeys. This case report describes a case of traumatic alopecia in two donkeys secondary to mutual hair plucking behaviour. Two genetically unrelated, male castrated, 4-year-old Cotentin donkeys living together were presented for a 2-year history of alopecic, mainly nummular, nonpruritic lesions developing on the back, loin and croup. The general physical examination and behavioural assessment were unremarkable. Trichoscopy, scrapings and cytology were performed. Superficial bacterial infection was diagnosed but a 2-week course of antibacterial treatment showed no improvement. Histopathological examination showed features compatible with traumatic alopecia and consistent with several behavioural causes of alopecia resembling human trichotillomania or acute traction alopecia, canine traction alopecia, feline self-induced alopecia and murine barbering. Separation of the donkeys led to complete long-term remission. Clinical and histopathological findings in our case share lots of similar features with the different mechanical traumatic alopecic disorders mentioned above, making it impossible to simply classify the described affection. Whether alopecic lesions resulted from an exclusive behavioural process (either abnormal excessive mutual grooming or other social interactions) or were associated with underlying causes of pruritus is uncertain. Mechanical alopecia secondary to a behavioural process should therefore be suspected in cases of permanent patchy alopecic nummular lesions on donkeys living in groups.     

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.     

Abnormal sebaceous gland differentiation in 10 kittens ('sebaceous gland dysplasia') associated with generalized hypotrichosis and scaling

A rare congenital dermatosis, characterized by progressive hypotrichosis with variable scaling and crusting, occurred in 10 short-haired kittens in North America and Europe. Lesions appeared at between 4 and 12 weeks of age, commencing on the head and becoming generalized. The tail was spared in two kittens. Generalized scaling was mild to moderate, often with prominent follicular casts. Periocular, perioral, pinnal and ear canal crusting was occasionally severe. The skin was thick and wrinkled in two kittens. Histologically, the main lesion was abnormal sebaceous gland morphology. Instead of regular differentiation from basal cells to mature sebocytes, the glands were composed of a haphazard collection of undifferentiated basaloid cells, some partly vacuolated and a few containing eosinophilic globules. Mitotic figures and apoptotic cells were present in an irregularly thickened follicular isthmus. Lymphocytic mural folliculitis and mild sebaceous adenitis were rare. Orthokeratotic hyperkeratosis and follicular casts were present. Hair follicles were of normal density and were mostly in anagen, but some contained malacic hair shafts. Perforating folliculitis, leading to dermal trichogranuloma formation, occurred occasionally. Further biopsy samples taken at 2 years and at 3 and 4 years, respectively, from two kittens revealed similar but often more severe sebaceous gland lesions. Hair follicles were smaller, with many in telogen. The young age of onset suggests a genetic defect interfering with sebaceous and, possibly, follicular development. These lesions are discussed with reference to studies of mouse mutants in which genetic defects in sebaceous differentiation cause a similar phenotype of hyperkeratosis and progressive alopecia.     

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.     

Focal cutaneous vasculitis and alopecia at sites of rabies vaccination in dogs

A focal cutaneous lesion developed at the site of previous rabies vaccine administration in 13 dogs. Ten of the affected dogs were Poodles. The interval between vaccination and first observation of the lesion varied from 3 to 6 months. Skin lesions were hyperpigmented, alopecic macules, 2 to 5 cm in diameter. The consistent histologic lesion was vasculitis affecting arterioles of the deep dermis and subcutis. Other histologic lesions included epidermal, follicular, and adnexal atrophy, hyperpigmentation, chronic septal panniculitis, fat necrosis, and focal lymphocytic nodules in the deep dermis and subcutis. Rabies-specific fluorescence was seen in the walls of dermal blood vessels and in the epithelium of hair follicles in each of 3 dogs tested. Immunoglobulin G was detected in similar locations in one of 3 dogs tested. No difference in serum neutralizing anti-rabies antibody titers were detected between 5 affected dogs tested and 4 clinically normal dogs.     

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.     

Effects of cyclosporine A on clinical and histologic abnormalities in dogs with sebaceous adenitis

OBJECTIVE: To evaluate the effects of cyclosporine A in the treatment of sebaceous adenitis in dogs. DESIGN: Open-label clinical trial. ANIMALS: 12 dogs with sebaceous adenitis. PROCEDURE: Dogs were treated with cyclosporine A at a dosage of 5 mg/kg/d (2.3 mg/lb/d), PO, for 12 months and reevaluated every 4 months. A clinical score was calculated by grading the extent of alopecia and severity of follicular casts as absent, mild, moderate, or severe in each of 17 body regions. Biopsy specimens were obtained and examined histologically and by means of immunohistochemical staining. RESULTS: Mean clinical score was significantly decreased, compared with baseline score, after 4 months of treatment and remained low after 8 and 12 months. Histologically, the severity of inflammation was significantly decreased, as were numbers of macrophages, CD3+ T cells, and major histocompatibility complex class II-expressing cells. The percentage of hair follicles with sebaceous glands increased, suggesting regeneration of sebaceous glands. Clinical signs recurred when cyclosporine administration was discontinued. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that administration of cyclosporine A at a dosage of 5 mg/kg/d may reduce the inflammation associated with sebaceous adenitis in dogs. Long-term treatment appears to be neccessary to control the disease.     

Generalized alopecic and cystic dermatosis in a cat: a counterpart to the hairless mouse phenotype or a unique congenital dermatosis?

A 2-year-old, male neutered, domestic semi-long-haired cat was presented with a 1.5-year history of progressive, initially nonpruritic alopecia and malodorous greasy exudate affecting the distal extremities, trunk and neck but sparing the head and tail. The extensive alopecia and 'seborrhoea' were associated with severe thickening of the skin and fold formation on the dorsal head and distal extremities as well as the lateral thorax and abdomen. The hair was easily epilated, numerous milia were seen on the ventral abdomen and the caudal and lateral thighs, and mild paronychia was present. Histopathological examination of skin biopsies revealed marked cystic dilation of hair follicles and sebaceous glands with follicular hypoplasia, infundibular hyperkeratosis and variable associated inflammation. Systemic glucocorticoid therapy in combination with topical washes with chlorhexidine and miconazole resulted in a marked improvement and some hair regrowth, but the cat was subsequently lost to follow-up. The dermatosis resembles a number of conditions in other species, but it is not clear whether it is a counterpart to the hairless mutant mouse or is a unique dermatosis.     

Traction alopecia with vasculitis in an Old English sheepdog

A seven-year-old entire male Old English sheepdog was presented with a well circumscribed, completely alopecic area on the top of its head, located where a rubber band had been used for several years. A punch biopsy was taken from the centre of the lesion and histological examination revealed cell-poor, interface mural folliculitis with follicular atrophy and vasculitis. A diagnosis of traction alopecia was made. Oral pentoxyfilline, at 400 mg twice daily, was prescribed for two months, with a slight improvement. To the authors' knowledge, this is the first report of canine traction alopecia accompanied by vascular damage. This vascular damage may represent the pathomechanism of this type of alopecia in the dog.     

Follicular dysplasia in two cows

The histological features of a follicular dysplasia with pigmentary changes is reported in two adult cows, one a black Brangus-cross and the other a black Angus. Adult onset of diffuse alopecia was present in both cows. Skin biopsies exhibited follicular distortion and atrophy, with melanin clumping in follicular epithelium, hair bulb matrix cells, hair shafts, and infundibular keratin. Both animals were clinically normal apart from the alopecia. This report confirms and expands on the infrequently reported syndrome of follicular dysplasia in cattle.     

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.     

Black-hair follicular dysplasia in a New Zealand Huntaway dog

CASE HISTORY: A 6-year-old intact male New Zealand Huntaway dog had slowly progressive alopecia that was first observed at 12 weeks of age.

CLINICAL FINDINGS: Patchy alopecia was confined to the black-haired areas of the body, and was most evident on the head and dorsum of the body; tan-haired areas of skin appeared normal. Histological examination of black-haired skin revealed distended melanocytes and large aggregates of melanin within, and surrounding, the hair follicles and the epidermis. Macrophages distended with melanin were also visible within the perifollicular and superficial dermis, and follicular lumina were often plugged by keratin that contained aggregates of melanin. The follicles were dysplastic and few hair shafts were visible emerging from follicular infundibula within the sections.

DIAGNOSIS: The clinical and histological findings were consistent with black-hair follicular dysplasia (BHFD).

CLINICAL RELEVANCE: This is the first report of BHFD in a dog in New Zealand, and is the first report in a Huntaway. The most significant effect of BHFD is a predisposition to follicular plugging and secondary bacterial skin infections. Due to the hereditary nature of the follicular dysplasias, breeding from affected dogs should be discouraged. Histological examination of the skin is required to differentiate between the different follicular dysplasias as well as differentiating between follicular dysplasia and follicular atrophy due to endocrinopathy.     

Alopecia in pomeranians and miniature poodles in association with high urinary corticoid:creatinine ratios and resistance to glucocorticoid feedback

The adrenocortical function of pomeranians and miniature poodles with alopecia was tested by serial measurements of the urinary corticoid:creatinine ratio (uccr) and by an oral low-dose dexamethasone suppression test (lddst) and uccr measurements. In most of the dogs there was day-to-day variation in the uccrs of the 10 sequential urine samples, often with values above or below the upper limit of the range of healthy control dogs. In 22 alopecic pomeranians the basal uccrs were significantly higher than in 18 non-alopecic pomeranians, and the values of both groups were significantly higher than those of 88 healthy pet dogs. The uccrs of 12 alopecic miniature poodles were significantly higher than those of healthy dogs. In 12 alopecic pomeranians and eight alopecic miniature poodles the oral lddst revealed increased resistance to dexamethasone. In six non-alopecic pomeranians the uccrs after the administration of dexamethasone were not significantly different from those in seven healthy dogs at the same time. In an oral high-dose dexamethasone suppression test, using 0.1 mg dexamethasone/kg bodyweight, the uccrs of seven alopecic pomeranians and five alopecic miniature poodles decreased to low levels.     

Congenital follicular dysplasia in five related coatimundis (Nasua nasua)

We report a congenital follicular dysplasia in five coatis from four different litters of the same parents born between 1996 and 2001. These coatis were born apparently alopecic with the entire body covered by very short dark hairs, with secondary lichenification of the skin, crusting and scaling. The main histopathological feature consisted of premature cornification of the cortical cells of the hair shaft. Cells were already fully cornified below the Adamson's fringe, leading to a disorganized, fragmented and constricted hair shaft. Based on the history of the animals and the nature of the lesions, a genetic defect in hair shaft keratinization was suspected.     

Successful treatment of sebaceous adenitis in a rabbit with ciclosporin and triglycerides

A 4-year-old rabbit was presented with a chronic exfoliative dermatitis and patchy alopecia. General physical examination revealed no abnormalities. Skin scrapings and fungal culture were negative. A blood sample was obtained for a complete blood cell count and biochemical profile, and yielded results that were within normal limits. Radiographic examination of the thorax excluded the presence of a thymoma. Histopathology of the skin showed orthokeratotic hyperkeratosis, absence of sebaceous glands and mural lymphocytic folliculitis, consistent with sebaceous adenitis. Oral treatment was started with ciclosporin dissolved in a medium-chain triglyceride solution (Miglyol 812), combined with essential fatty acids and topical propylene glycol sprays. Within 2 months of treatment, complete regression of skin lesions and regrowth of hair was observed. Serum chemistry values including kidney and liver function tests remained within reference range during the course of treatment. Histopathological examination of control biopsies of the skin showed presence of normal sebaceous glands and active hair follicles. Treatment was changed to a different pharmaceutical formulation of ciclosporin without Miglyol and deterioration of clinical signs was noticed. Using pure Miglyol 812, however, resulted in a gradual improvement of 60%. A nearly complete response was again observed after re-administration of the combination ciclosporin/Miglyol. It is hypothesized that sebaceous adenitis in the rabbit is most likely due to an autoimmune reaction directed at the sebaceous glands and a defect in lipid metabolism. The outcome indicates that a combination of ciclosporin and Miglyol 812 is a promising new treatment for sebaceous adenitis in rabbits.     

Follicular dysplasia in five Weimaraners

This study evaluated the clinical and histopathological features and results of light and electron scanning microscopy assessments of follicular dysplasia in five Weimar Pointers. The data were compared with those obtained in three normal Weimaraners. In our study, this dermatosis affected young adults that showed progressive alopecia of the trunk (head and limbs were spared) associated with recurrent folliculitis/furunculosis. Exclusion of other dermatoses and the presence of histopathological lesions and hair shafts abnormalities seen in light and/or scanning electron microscopy similar to colour dilution alopecia led to the diagnosis of follicular dysplasia. The lesions we observed are the same as those described previously in colour dilution alopecia, but they were less pronounced in all our samples.