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.     

Parvovirus infection in pigs with necrotic and vesicle-like lesions

Porcine parvovirus was isolated from many visceral organs and also from the brain, serum and skin specimens of swine with vesicular-like conditions. Severe lesions were reported to have occurred in the mouth, on the tongue and snout, on the coronary band and in the interdigital spaces. Also, parvoviral antigens were demonstrated, by immunofluorescence, in the outer layer of hair follicles in skin adjacent to coronary band lesions.     

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.     

Subepidermal bullous dermatosis due to topical corticosteroid therapy in dogs

Six adult dogs were presented with an unusual bullous dermatosis affecting the glabrous skin of the ventral abdomen and medial thighs. Clinically, flaccid bullae were accompanied by erythema, ulceration, haemorrhage and hyperpigmentation in four of six dogs; the remaining two dogs had thin skin without grossly apparent bullae. Histologically, subepidermal bullae and clefting, vascular proliferation and dilatation (phlebectasia), and alteration in the density and staining of superficial dermal collagen were seen in all dogs. In all cases, corticosteroid-containing topical products had been applied to the affected areas prior to the development of the dermatosis; skin lesions resolved when topical corticosteroids were withdrawn. Follow-up biopsy of three dogs showed resolution of the previously abnormal collagen and subepidermal clefting. Residual lesions included phlebectasia, comedones and hyperpigmentation. The authors postulate that subepidermal clefting was due to local, corticosteroid-induced skin fragility. This is the first report, to our knowledge, of bullous skin disease in dogs resulting from topical corticosteroid therapy.     

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.     

Colonisation status of Malassezia pachydermatis on the hair and in the hair follicle of healthy beagle dogs

Hair and hair follicle carriage of Malassezia pachydermatis was studied in 12 healthy beagle dogs. The yeast was isolated from hair clipped from the lip region at 13 sites in nine dogs but was less frequently recovered from the interdigital spaces on the forefeet and from two sites on the trunk. Population sizes at the lip were significantly greater (P < 0.01) than those at other sites. Skin biopsy specimens were obtained from the same sites and epidermal and follicular tissues dissected following immersion in 1 M CaBr(2). Epidermal carriage of M. pachydermatis was identified in nine biopsy specimens taken from five dogs. Hair follicle carriage was identified in five skin specimens (four foot, one lip) from three dogs. This study indicates that M. pachydermatis is readily recovered from the distal hair in healthy dogs and that hair follicle carriage is infrequent or that populations are low at that site.     

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.     

Bald thigh syndrome of Greyhound dogs: gross and microscopic findings

Bald thigh syndrome (BTS) is a disease limited to Greyhound dogs. It is characterized clinically and grossly by bilateral hair loss on the lateral and caudal thighs. The cause of BTS is unknown but may be associated with hypothyroidism or hyperadrenocorticism. Samples of skin, thyroid glands, and adrenal glands from 43 Greyhound dogs with BTS were examined microscopically. Microscopic changes were characterized by dilatation of follicular infundibula, presence of catagen follicles and epidermal hyperplasia. Changes in the skin from these Greyhound dogs suggest an endocrinopathy as the cause; however, we were unable to confirm which one.     

FC-12 Diagnostic value of skin biopsy in feline symmetric alopecia

Hair loss in Chesapeake Bay retrievers has been increasingly recognized by breeders in recent years. Anecdotal reports suggest an endocrine disorder or follicular dysplasia as the underlying cause, but no scientific study has been done to investigate the underlying problem. A prospective study was carried out in collaboration with the American Chesapeake Club. Affected dogs were recruited into the study. Routine dermatological and hormonal (blood and urine) tests, and skin biopsies were performed. Ten dogs (age 1.5–10 years), seven females (two spayed) and three males (two neutered), were included in the study. All dogs had mild or severe hair loss affecting the lateral ventral chest, flanks, rump and thighs. Affected dogs were clinically healthy. Hormonal tests revealed normal thyroid hormone panels, insulin-like growth factor-1 levels, and urinary cortisol:creatinine ratios in samples collected for ten consecutive days. In six of 10 dogs, an adrenal hormone panel showed slight or moderate increased values pre- and/or post-ACTH stimulation of cortisol (three of six), 17-hydroxyprogesterone (five of six), androstenedione (three of six), estradiol (two of six) and progesterone (six of six). The major histopathologic changes resembled canine flank alopecia and follicular dysplasia with pronounced infundibular hyperkeratosis, mild follicular atrophy, and occasional melanin clumping with dystrophic hair shafts. Chesapeake Bay retrievers suffer from a type of hair loss that is likely related to an abnormal production of adrenal sex hormone. Further studies are currently underway to determine if there is a heritable basis for this disease and to evaluate therapeutic options.
Funding: University of Pennsylvania.     

Histologic features of hair follicle neoplasms and cysts in dogs and cats: a diagnostic guide

Hair follicle neoplasms occur in many different species, including humans. In domestic animals, they are most common in dogs. Most hair follicle tumors are benign, but malignant neoplasms can also occur. To diagnose hair follicle neoplasms, a thorough knowledge of follicular anatomy is important, given that follicular tumors are classified according to the differentiation pattern seen in the corresponding part of the normal hair follicle. This review focuses on the key diagnostic features of hair follicle tumors and follicular cysts in dogs and cats.     

Nerve sheath tumours in the dog and cat

Schwannomas were diagnosed in twelve dogs and five cats at Massey University Small Animal Clinic and Hospital over a 15-year period (1977-92). A further two feline cases were reported at the Batchelar Animal Health Laboratory. In six dogs, the tumour involved nerves of the brachial plexus. Clinical signs observed in these dogs were forelimb lameness, muscle wasting and pain on movement of the affected limb or neck. Hindlimb paresis was observed in two dogs. Surgical excision of the brachial plexus tumour was attempted in one dog, leading to an 8-month remission of signs. In one dog, the tumour involved the sacral nerves, and in two dogs the cranial nerves were affected. Three dogs had skin nodules. Seven of the twelve affected dogs were destroyed. In five cats, the tumours developed on the carpus, tarsus or interdigital area of a forelimb or hindlimb as a slowly developing nodular lesion. In the other two cats, the site of the tumour was the flank and the lateral thigh respectively. Surgical excision of the tumour was successful in three cats.     

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

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

FC‐10 Adult‐onset hair loss in Chesapeake Bay retrievers: a clinical and histological study

Hair loss in Chesapeake Bay retrievers has been increasingly recognized by breeders in recent years. Anecdotal reports suggest an endocrine disorder or follicular dysplasia as the underlying cause, but no scientific study has been done to investigate the underlying problem. A prospective study was carried out in collaboration with the American Chesapeake Club. Affected dogs were recruited into the study. Routine dermatological and hormonal (blood and urine) tests, and skin biopsies were performed. Ten dogs (age 1.5–10 years), seven females (two spayed) and three males (two neutered), were included in the study. All dogs had mild or severe hair loss affecting the lateral ventral chest, flanks, rump and thighs. Affected dogs were clinically healthy. Hormonal tests revealed normal thyroid hormone panels, insulin‐like growth factor‐1 levels, and urinary cortisol:creatinine ratios in samples collected for ten consecutive days. In six of 10 dogs, an adrenal hormone panel showed slight or moderate increased values pre‐ and/or post‐ACTH stimulation of cortisol (three of six), 17‐hydroxyprogesterone (five of six), androstenedione (three of six), estradiol (two of six) and progesterone (six of six). The major histopathologic changes resembled canine flank alopecia and follicular dysplasia with pronounced infundibular hyperkeratosis, mild follicular atrophy, and occasional melanin clumping with dystrophic hair shafts. Chesapeake Bay retrievers suffer from a type of hair loss that is likely related to an abnormal production of adrenal sex hormone. Further studies are currently underway to determine if there is a heritable basis for this disease and to evaluate therapeutic options. Funding: University of Pennsylvania.     

Histopathologic features of canine distichiasis

Objective To describe the histologic features of canine distichiasis using excised tarsoconjunctival specimens that included roots of distichiatic cilia. Procedures The study group included 21 strips of cilia‐bearing tarsoconjunctiva resected from 20 dogs with distichiasis. Eyelid tissue specimens were also collected from 11 euthanized dogs without distichiasis to serve as controls. All flat mount preparations were processed for histologic examination, and serial sections were stained with hematoxylin‐eosin (H&E). A total of 157 slides were examined for the study group to describe the follicles and path of the distichiatic hairs and determine their potential connection with the tarsal glands. A total of 82 slides were examined for the control group. Results In 19 of the 20 dogs with distichiasis, serial sections of the specimens identified anatomic segments of hair follicles located abnormally in the eyelid tarsus and associated with the aberrant cilia. They appeared as hair bulbs adjacent to tarsal glands, middle portions of hair follicles located between sebaceous lobules, and single or multiple hair shafts present within the sebaceous duct. The tarsal glands in the cilia‐bearing tarsoconjunctiva were not different from those of the controls, in which no distichiatic hair bulbs or shafts were observed. Conclusions These results demonstrate that adventitious cilia are not associated with histologic changes of the tarsal glands, and appear to arise from ectopic hair follicles present in the tarsus. Canine distichiasis may result from anomalous regulation of morphogenesis of hair follicles in the mesenchymal tissue of the tarsal plate.     

Bacteria and yeast on the surface and within non-inflamed hair follicles of skin biopsies from dogs with non-neoplastic dermatoses.

Coccoid bacteria and/or yeasts were found in the surface keratin or exudate and/or in the pilar canal of non-inflamed hair follicles upon light microscopic examination of skin biopsies from 191 of 3,387 dogs (5.6%) with non-neoplastic skin disorders. The presence of surface cocci and/or yeast did not appear to suggest a specific dermatosis, nor the existence of a clinically relevant infection in the majority of cases. However, follicular cocci and/or yeast almost always indicated the presence of a clinically relevant infection.     

Fate of cystic ovarian follicles and the subsequent fertility of early postpartum dairy cows

The fate of cystic ovarian follicles that developed spontaneously during the early postpartum period of 50 lactating dairy cows was traced by ultrasonography to characterise the follicular dynamics in relation to the fertility of the cows. The absence of postpartum ovulations caused by repeated waves of anovulatory large follicles was also characterised and evaluated. Fifteen of the 50 cows developed cystic follicles, and these follicles became follicular cysts in five of the 15 cows. Most of the cystic follicles emerged before the first postpartum ovulation of the cows. The transition from cystic follicles to follicular cysts delayed the cows' first ovulation, oestrus and insemination, but had less influence on their fertility after they had recovered spontaneously. In addition to the 15 cows that developed cystic follicles or follicular cysts, six of the cows had five to 13 waves of follicles before their first ovulation. These repeated waves of follicles caused a more severe delay in the early postpartum reproductive events but did not affect the cows' fertility.     

Comparison of different methods of diagnosis of cystic ovarian disease in cattle and an assessment of its treatment with a progesterone-releasing intravaginal device

The aims of this study were to assess the accuracy of different common methods of differentiating between follicular and luteal ovarian cysts, and to monitor the response of the cysts to 12 days treatment with a progesterone-releasing intravaginal device (PRID). On the basis of agreement between the different methods, 25 of the 46 cases examined were diagnosed as follicular and 14 as luteal cysts; for the other seven cases the methods disagreed. The use of ultrasound was more accurate in diagnosing follicular cysts than luteal cysts, and combined with plasma progesterone concentrations gave the most accurate assessment of cyst type (92 per cent for follicular cysts and 82 per cent for luteal cysts). The mean (se) plasma progesterone concentration was lower in the cows with follicular cysts than in those with luteal cysts (0.29 [0.05] v 3.90 [0.63] ng/ml; P<0.05). Luteal cysts had thicker walls (5.3 [0.04] v 2.5 [0.2] mm; P<0.0001), and the wall thickness of all the cysts was positively correlated with plasma progesterone concentration (r=0.52, P<0.0004). Cows with luteal cysts had more additional follicles greater than 5 mm in diameter (P<0.01). In cows with follicular cysts and other follicles greater than 5 mm in diameter, the mean oestradiol concentration was 7.9 (1.8) pg/ml compared with 24.2 (3.1) pg/ml (P=0.002) in cows without other follicles greater than 5 mm in diameter on either ovary. At the time of PRID removal, plasma progesterone concentration had increased in the cows with follicular cysts to 1.59 (0.06) ng/ml (P<0.05) and decreased in the cows with luteal cysts to 0.87 (0.01) ng/ml (P<0.05), although there was no change in original cyst structure in 45 per cent of the cases. However, new ovarian structures were frequently observed during the treatment. The overall pregnancy rate for cows with both types of cyst after treatment was 50 per cent after three inseminations, but the first service pregnancy rate was only 18 per cent for cows with follicular cysts and 28 per cent for cows with luteal cysts. After treatment, the fertility of cows with follicular cysts was similar to that of paired herdmates, whereas cows with luteal cysts took 40 days longer to calve again than healthy herdmates. However, the culling rate was higher for cows with follicular cysts (41 v 11 per cent).     

Relative sensitivity of hair pluckings and exudate microscopy for the diagnosis of canine demodicosis

This study was designed to compare the sensitivity of deep skin scraping, hair plucking, and exudate microscopy for the diagnosis of canine demodicosis. Sixty-seven dogs diagnosed with demodicosis were enrolled in the study. Thirty dogs had localized and 37 had generalized demodicosis. Twenty-seven of the 67 dogs had complicated (secondarily infected) and 40 had noncomplicated form. On each dog, a single lesion was randomly selected to obtain one deep skin scraping, hair plucking, and, when present (n = 13) exudate. For skin scraping and exudate microscopy, an area under a cover slip measuring 2.2 x 2.2 mm was examined, while trichography included the evaluation of 100 hair shafts. At least one parasitic element was found in 85.1% of trichograms, and 100% of exudate preparations. The number of parasitic elements was higher in skin scrapings compared to the other two methods. The diagnostic sensitivity of skin scrapings was higher than that of hair pluckings for the total number of samples (P = 0.002) and for those obtained from dogs with the localized (P = 0.004) and the noncomplicated (P = 0.002) forms of the disease. The diagnostic sensitivity of hair pluckings was higher in generalized and complicated demodicosis compared to the localized and noncomplicated variants. Based on these results, exudate microscopy may be equally sensitive to deep skin scrapings, and trichography may be of value in generalized and complicated demodicosis, although a negative result cannot rule it out.     

Fusion podoplasty for the management of chronic pedal conditions in seven dogs and one cat

Eight animals underwent fusion podoplasties for the treatment of chronic interdigital furunculosis (n=3), ectrodactyly (n=1), digit abnormalities associated with tendonectomy (n=1), redundant indertigital skin (n=1), conformational deformity (n=1), and necrotizing fasciitis of the paw (n=1). Median duration of bandaging was 14 days, and median duration of hospitalization was 5 days. Four dogs had dehiscence, which occurred at a mean time of 11 days after surgery. Clinical abnormalities necessitating podoplasty resolved in six animals and improved in two. Six animals had normal ambulation and two dogs had slight weight-bearing lameness after a median follow-up time of 29 mo. Fusion podoplasty may be recommended as a salvage procedure for the treatment of various chronic pedal diseases in dogs and cats.