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.     

Oestrogen-induced alopecia in a bitch

An 8-year-old, spayed female Labrador Retriever, which had been treated with oestrogens for urinary incontinence, developed non-pruritic, bilaterally-symmetrical alopecia and skin hyperpigmentation, with enlargement of mammary glands and vulva. Skin biopsy changes were consistent with an endocrine alopecia, hypothyroidism and hyperadrenocorticism were excluded by hormonal tests. Oestrogen-induced alopecia was suspected and hormonal treatment withdrawn. Two months later, hair regrowth was almost complete and genital changes were lessened.     

Oestrogen receptor antagonist and hair regrowth in dogs with hair cycle arrest (alopecia X)

An oestrogen receptor pathway that regulates the telogen-anagen hair follicle transition in mice has been described. The purpose of this study was to investigate whether fulvestrant, a pure oestrogen receptor antagonist, would cause hair regrowth in Pomeranian dogs with hair cycle arrest (alopecia X). Eleven Pomeranian dogs with hair cycle arrest were randomly assigned to receive two intramuscular injections of either 10 mg kg(-1) fulvestrant (n = 6) or an equal volume of saline (n = 5) 1 month apart. Complete blood count, chemistry panel, and urinalysis were monitored prior to the first injection and monthly for 2 months. Dogs were evaluated each month for degree of hair growth, percentage of body affected, and quality of new hair growth. Three control dogs received fulvestrant after the completion of the study. In addition, one control dog and one treatment dog received two subcutaneous injections of 20 mg kg(-1) fulvestrant 1 month apart. No dogs that received 10 mg kg(-1) fulvestrant had any evidence of hair regrowth. The control dog that received 20 mg kg(-1) fulvestrant had substantial hair regrowth 1 month after the first injection. No adverse effects from the treatment were noted. Fulvestrant does not appear to be a feasible treatment for dogs with hair cycle arrest (alopecia X) when administered intramuscularly at 10 mg kg(-1). A higher dose of fulvestrant requires more investigation but may be cost-prohibitive.     

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.     

The effects of thyroid hormones on the skin of beagle dogs

The effects of hypothyroidism on canine skin were determined by comparing morphologic, morphometric, and hair cycle differences in skin biopsy samples from 3 groups of age- and gender-matched Beagle dogs: (1) euthyroid dogs; (2) dogs made hypothyroid by administration of 131I; and (3) dogs made hypothyroid and maintained in a euthyroid state by treatment with synthetic thyroxine. After 10 months of observation, there was slower regrowth of hair 2 months after clipping in the untreated-hypothyroid dogs. Untreated-hypothyroid dogs had a greater number of follicles in telogen and fewer hair shafts (ie, a greater number of hairless telogen follicles) than did the control group. The control dogs had a greater number of telogen follicles but the same number of hair shafts as the treated-hypothyroid group. Treated-hypothyroid dogs had the greatest number of follicles in the growing stage of the hair cycle (anagen). This study suggests that, at least in Beagles, induced hypothyroidism does not affect the pelage as dramatically as has been described in naturally occurring disease. This is because normal Beagles retain hair shafts in follicles for long periods, and the alopecia of hypothyroidism appears to evolve slowly because of the prolongation of this haired telogen stage. The evaluation of thyroxine-treated hypothyroid dogs demonstrates that thyroid hormone supplementation of Beagle dogs with induced hypothyroidism stimulates hair growth.     

Isolation of Microsporum vanbreuseghemii from skin lesions of a dog

Routine examination of a 12-week-old Labrador Retriever revealed circular scaly lesions, with alopecia, on the lateral aspect of the left carpus and left upper eyelid. The geophilic fungus Microsporum vanbreuseghemii was isolated from the lesions. Topical treatment with chlorhexidine ointment resulted in resolution, with hair regrowth.     

Corynebacterium folliculitis in a horse

A 7-year-old Thoroughbred was examined for evaluation of mildly pruritic multiple skin lesions that had progressed from nodules to alopecia and crusts. Folliculitis caused by Corynebacterium pseudotuberculosis was diagnosed by bacterial culture. Oral treatment with a trimethoprimsulfadiazine paste resulted in resolution of all lesions, with normal hair regrowth.     

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.     

Alopecia in a black Labrador retriever associated with focal sub‐follicular panniculitis and sebaceous adenitis

A 6‐year‐old entire male black Labrador retriever was presented with nonpruritic multicentric, well‐demarcated alopecia of 12‐weeks duration. Skin biopsies from the margins of alopecic regions showed sebaceous adenitis and sub‐follicular panniculitis. Biopsies from alopecic areas showed severe follicular atrophy with residual fibrous tracts, loss of sebaceous glands and lymphohistiocytic panniculitis beneath individual atrophic hair follicle groups. These features differed from previous reports of pilosebaceous diseases of dogs and appeared to extend the spectrum of inflammatory patterns in presumed immune‐mediated adnexal diseases of this species. During the 12‐month follow‐up, there was partial hair regrowth without treatment but alopecia was permanent in the centre of larger lesions.     

The effects of clomipramine hydrochloride in cats with psychogenic alopecia: a prospective study

A double-blind, placebo-controlled clinical trial was conducted to determine the efficacy of clomipramine hydrochloride in cats with psychogenic alopecia. Twenty-five cats were randomly assigned to receive clomipramine hydrochloride (0.5 mg/kg orally q 24 hours) or placebo for 56 days. Eleven cats in each group completed the trial. The results of this study showed that clomipramine hydrochloride failed to demonstrate significant changes in the number of grooming bouts, hair regrowth, and the area of alopecia in cats with psychogenic alopecia when compared to a placebo. It was uncertain whether these results reflected a lack of drug efficacy, insufficient treatment duration, or an insufficient number of cases enrolled.     

Growth hormone responsive dermatosis in three dogs

Growth hormone responsive dermatosis was diagnosed in three dogs. Each dog showed truncal hair loss, and two animals also had alopecia of the ventral neck, tail and thighs. The diagnosis in two cases was made by eliminating other causes of hormonal alopecia and demonstrating little increase in plasma growth hormone concentration after the intravenous administration of xylazine. All three dogs responded favourably to the subcutaneous administration of recombinant human somatotropin.     

Growth hormone responsive dermatosis in three dogs

Growth hormone responsive dermatosis was diagnosed in three dogs. Each dog showed truncal hair loss, and two animals also had alopecia of the ventral neck, tail and thighs. The diagnosis in two cases was made by eliminating other causes of hormonal alopecia and demonstrating little increase in plasma growth hormone concentration after the intravenous administration of xylazine. All three dogs responded favourably to the subcutaneous administration of recombinant human somatotropin.     

Demodicosis in nine prairie dogs (Cynomys ludovicianus)

This case report describes the clinical signs and treatment of demodicosis in nine pet prairie dogs (Cynomys ludovicianus). Clinical records including history, clinical examination, microscopic evaluation and fungal culture of the skin lesions were available for all nine animals. In seven animals, blood was obtained for haematological and biochemical analyses. Clinical signs comprised bilaterally symmetrical alopecia extending from the middle part of the back down to the skin of the thighs and the dorsal and ventral parts of the tail. Demodex mites were found in skin scrapings from all cases. Treatment with amitraz at 250 p.p.m. resulted in resolution of lesions and hair regrowth. This is the first report of demodicosis in this species.     

Hair growth in the greyhound

Monthly regrowth of clipped hair was measured in greyhounds over a two-year period; plasma progesterone and testosterone were measured at the time of clipping. Entire males and females showed virtually no growth in late winter and late summer while maximal growth occurred in mid-summer. Oestrus, and its associated hormones, appeared to suppress hair growth in entire females while spayed females showed good growth throughout most of the year. Low environmental temperature was considered to depress growth in late winter.     

Inherited alopecia X in Pomeranians

Four male Pomeranians that showed alopecia with an age of onset between five months and eight years were investigated.The aim of the investigation was to clarify whether the affected dogs had alopecia X and whether their symptoms might be due to a hereditary defect.The four affected dogs showed hairless patches at the root of the tail, at the back, at the limbs from the thigh to the tarsus and at the abdomen. Within the hairless patches some islets with sparse hair were present. In hairless patches the skin was dark pigmented. Besides the alopecia and hyperpigmentation no other symptoms were found according to anamnestic and clinical examination. History, clinical examinations, laboratory diagnostics, and histopathology of skin biopsies allowed the diagnosis of alopecia X in three affected male dogs.The last one of the affected dogs additionally had slightly reduced thyroid hormone levels. Based on identical symptoms and the close relatedness of all four animals, it was assumed that the fourth affected dog also had alopecia X.The available data possibly indicate a monogenic autosomal dominant inheritance, however a recessive inheritance can not be excluded at this time.     

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.     

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.     

Treatment of canine Alopecia X with trilostane

Sixteen Pomeranians and eight miniature poodles presenting with clinical signs of alopecia X, elevated blood concentrations of 17-hydroxyprogesterone post stimulation with adrenocorticotropic hormone and increased urinary cortisol/creatinine ratios were treated with trilostane, a competitive inhibitor of 3beta-hydroxysteroid dehydrogenase. Trilostane was given once or twice daily at a mean dose of 10.85 mg kg(-1) day(-1). Adrenal function was evaluated with a follow-up of 28 months in the Pomeranians and 33 months in the miniature poodles. Treatment with trilostane led to complete hair re-growth in 85% of the Pomeranians and in all of the miniature poodles within 4 to 8 weeks. No adverse events attributed to treatment with trilostane were recognized. The hair re-growth might have been the result of a down-regulation of adrenal steroids and/or of the noncompetitive inhibition of the oestrogen receptors at the hair follicle level.     

Alopecia in the horse – an overview

Dr Stannard explains different forms of alopecia in the horse with emphasis on the hair follicle and its function in the production of hairs. Both normal and abnormal patterns of hair growth and shedding in the horse are reviewed. Overviews of several specific hair follicle abnormalities, both inflammatory and noninflammatory, are discussed in detail with their clinical relevance. Some of the clinical entities covered in this section (linear alopecia and alopecia areata) are caused by immunological attack against normal structures and could have been placed in Immunologic diseases. However, because the clinical presentation for these entities is alopecia, Dr Stannard chose to include them in his notes on alopecia. Other inclusions in this section include cutaneous bacterial infections (e.g. pastern folliculitis and dermatophilosis) as well as fungal infections of the hair (dermatophytosis).     

The impact of body site, topical melatonin and brushing on hair regrowth after clipping normal Siberian Husky dogs

The aims of this study were to determine the impact of body site, vigorous brushing and topical melatonin treatment on hair regrowth after clipping normal dogs. Siberian Husky dogs were randomly assigned to three groups of eight dogs each. All dogs had the lumbosacral region and both lateral thighs clipped. The left thigh and lumbosacral area received no treatment and were compared in all 24 dogs. Eight dogs had the right thigh treated with 0.1% melatonin twice daily for 2 months, and hair regrowth was compared with the left thigh. Eight dogs had the right thigh brushed twice daily for 2 months, and hair regrowth was compared with the left thigh. Eight dogs had neither thigh treated. Hairs were plucked before and 2 months postclipping, and the proportion of hair growth from the original length was calculated and compared as described above. Biopsy samples were collected before and after treatment to determine if brushing induced dermal inflammation and melatonin increased the proportion of anagen follicles. Proportionally, left thigh hairs were significantly longer compared to lumbosacral hairs 2 months postclipping. No significant differences in hair regrowth were noted between the nontreated thigh and the thigh treated with melatonin or brushed. No significant difference in dermal inflammation was noted before and after brushing. No significant differences were observed in the proportion of anagen follicles before and after topical melatonin treatment. Our results showed that the hairs in the lumbosacral region were proportionally shorter than lateral thigh hairs 2 months postclipping. Moreover, topical melatonin and brushing had no impact on hair regrowth after clipping normal dogs.