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.     

Steroidogenic response of adrenal tissues after administration of ACTH to dogs with hypercortisolemia

OBJECTIVE: To evaluate adrenal sex hormone concentrations in neutered dogs with hypercortisolemia. DESIGN: Case series. ANIMALS: 11 neutered dogs with hypercortisolemia. PROCEDURE: Serum samples obtained before and 1 hour after administration of ACTH were evaluated for concentrations of cortisol, progesterone, testosterone, dehydroepiandrosterone sulfate or androstenedione or both, and 17-hydroxyprogesterone. RESULTS: For all dogs, concentrations of 1 or more adrenal sex hormones were substantially greater than reference range values before or after administration of ACTH. Testosterone concentration was not greater than reference range values in any of the dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Results emphasize the importance of ruling out hypercortisolemia before measuring adrenal sex hormone concentrations as a means of diagnosing adrenal hyperplasia syndrome (alopecia X) in dogs.     

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.     

Retrospective evaluation of sex hormones and steroid hormone intermediates in dogs with alopecia

The purpose of this study was to determine if there are specific steroid hormone aberrations associated with suspect endocrine alopecias in dogs in whom hypothyroidism and hyperadrenocorticism have been excluded. Steroid hormone panels submitted to the UTCVM endocrinology laboratory over a 7.5-year period (783 samples) from dogs with alopecia were reviewed. During this period, 276 dogs met the criteria for inclusion and were comprised of 54 different breeds. Approximately 73% of dogs had at least one baseline or post-ACTH stimulation steroid hormone intermediate greater than the normal range. The most frequent hormone elevation noted was for progesterone (57.6% of samples). When compared with normal dogs, oestradiol was significantly greater in Keeshond dogs and progesterone was significantly greater in Pomeranian and Siberian Husky dogs. Not all individual dogs had hormone abnormalities. Chow Chow, Samoyed and Malamute dogs had the greatest percentage of normal steroid hormone intermediates of the dogs in this study. Baseline cortisol concentrations were significantly correlated with progesterone, 17-hydroxyprogesterone (17-OHP) and androstenedione. Results of this study suggest that the pathomechanism of the alopecia, at least for some breeds, may not relate to steroid hormone intermediates and emphasizes the need for breed specific normals.     

Investigation of the reproductive and growth hormone status of dogs affected by idiopathic recurrent flank alopecia

The reproductive and growth hormone status of a group of 12 neutered dogs affected by idiopathic recurrent flank alopecia was investigated at both maximum and minimum photoperiod using the adrenocorticotrophic hormone (ACTH) stimulation test, the xylazine stimulation test and the insulin-like growth factor I (IGF-I) assay. When compared with a group of nine neutered control dogs, the plasma reproductive hormone concentrations were not significantly different with one exception; a significantly greater post-ACTH plasma progesterone concentration was detected in the affected group at minimum photoperiod (P<0–05). The significance of this finding in isolation is unclear. Growth hormone response to intravenous xylazine was assessed in the affected group at maximum photoperiod only and was found to be within normal limits in eight of the dogs. Serum IGF-I concentrations were significantly greater in the affected group at maximum photoperiod but the groups were not significantly different at minimum photoperiod. These results suggest that dogs with idiopathic recurrent flank alopecia are of normal reproductive and growth hormone status.     

Pituitary dwarfism in German Shepherd Dogs

Eleven German Shepherd dogs with pituitary dwarfism were examined. They were severely stunted in growth and possessed abnormal hair coats with persistence of the soft puppy (lanugo) coat and symmetrical areas of alopecia. Various other physical defects were often present in affected dogs. Detailed hormonal studies demonstrated a severe deficiency in growth hormone in all five cases so evaluated. A decrease in somatomedin activity was present in three of these cases. Changes in growth plates epiphyses and ossification centres were apparent on radiographic examination of four of the eleven dogs. Epiphyseal dysgenesis was confirmed histologically in two of these cases. Of the six brains which were examined post mortem, four showed large cystic lesions involving the adenohypo–physis and two had pituitary hypoplasia with virtual absence of adenohy–pophyseal tissue.     

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.     

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.     

Effects of growth hormone secretagogues on the release of adenohypophyseal hormones in young and old healthy dogs

The effects of three growth hormone secretagogues (GHSs), ghrelin, growth hormone-releasing peptide-6 (GHRP-6), and growth hormone-releasing hormone (GHRH), on the release of adenohypophyseal hormones, growth hormone (GH), adrenocorticotropic hormone (ACTH), thyroid-stimulating hormone (TSH), luteinising hormone (LH), prolactin (PRL) and on cortisol were investigated in young and old healthy Beagle dogs. Ghrelin proved to be the most potent GHS in young dogs, whereas in old dogs GHRH administration was associated with the highest plasma GH concentrations. The mean plasma GH response after administration of ghrelin was significantly lower in the old dogs compared with the young dogs. The mean plasma GH concentration after GHRH and GHRP-6 administration was lower in the old dogs compared with the young dogs, but this difference did not reach statistical significance. In both age groups, the GHSs were specific for GH release as they did not cause significant elevations in the plasma concentrations of ACTH, cortisol, TSH, LH, and PRL. It is concluded that in young dogs, ghrelin is a more powerful stimulator of GH release than either GHRH or GHRP-6. Ageing is associated with a decrease in GH-releasing capacity of ghrelin, whereas this decline is considerably lower for GHRH or GHRP-6.     

Vaccine-induced ischemic dermatopathy in the dog

Post-rabies vaccination alopecia associated with concurrent multifocal ischemic dermatopathy was identified in three unrelated dogs. All dogs received subcutaneous rabies vaccine dorsally between the scapulae several months prior to observation of the initial area of alopecia at the vaccination site. All three dogs developed multifocal cutaneous disease within 1–5 months after the appearance of the initial skin lesion. Cutaneous lesions were characterized clinically by variable alopecia, crusting, hyperpigmentation, erosions, and ulcers on the pinnal margins, periocular areas, skin overlying boney prominences, tip of the tail, and paw pads. Lingual erosions and ulcers were observed in two dogs. Histopathologic examination of the skin revealed moderate to severe follicular atrophy, hyalinization of collagen, vasculopathy, and cell-poor interface dermatitis and mural folliculitis. Hypovascularity was demonstrated by diminished Factor VIII staining of blood vessels. Nodular accumulations of lymphocytes, plasma cells, and histiocytes in the deep dermis and panniculus also were noted at the rabies vaccination site. An atrophic, ischemic myopathy paralleling the onset of skin disease was identified in two dogs. Histological examination of muscle biopsy specimens demonstrated perifascicular atrophy, perimysial fibrosis, and complement (C) _5b-9 (membrane attack complex) deposition in the microvasculature of both dogs with myopathy. Marked improvement of the skin disease was obtained with oral pentoxifylline and vitamin E.     

Hypothyroidism in the dog: a retrospective study of sixteen cases

Sixteen dogs with confirmed hypothyroidism were reviewed. The diagnosis was based on subnormal plasma thyroxine concentration and poor response following TSH administration. Common clinical signs were alopecia (12 dogs), lethargy (11) and obesity (11). Plasma cholesterol concentrations were abnormally high in 10 of 14 cases tested, five of 12 were anaemic and three of five had increased creatine phosphokinase activity. Skin changes compatible with endocrinopathy were present in all five cases biopsied. Spontaneous muscle activity was found on electromyography in four cases so examined. All dogs were treated with sodium levothyroxine, and 10 of 13 for which information was available responded satisfactorily.     

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.     

Assessment of a combined anterior pituitary function test in beagle dogs: Rapid sequential intravenous administration of four hypothalamic releasing hormones

A combined anterior pituitary (CAP) function test was assessed in eight healthy male beagle dogs. The CAP test consisted of sequential 30-second intravenous administrations of four hypothalamic releasing hormones in the following order and doses: 1 μg of corticotropin-releasing hormone (CRH)/kg, 1 μg of growth hormone-releasing hormone (GHRH)/kg, 10 μg of gonadotropinreleasing hormone (GnRH)/kg, and 10 μg of thyrotropin-releasing hormone (TRH)/kg. Plasma samples were assayed for adrenocorticotropin, cortisol, GH, luteinizing hormone (LH), and prolactin (PRL) at multiple times for 120 min after injection. Each releasing hormone was also administered separately in the same dose to the same eight dogs in order to investigate any interactions between the releasing hormones in the combined function test.Compared with separate administration, the combined administration of these four hypothalamic releasing hormones caused no apparent inhibition or synergism with respect to the responses to CRH, GHRH, and TRH. The combined administration of these four hypothalamic releasing hormones caused a 50% attenuation in LH response compared with the LH response to single GnRH administration. The side effects of the combined test were confined to restlessness and nausea in three dogs, which disappeared within minutes after the administration of the releasing hormones. It is concluded that with the rapid sequential administration of four hypothalamic releasing hormones (CRH, GHRH, GnRH, and TRH), the adenohypophyseal responses are similar to those occurring with the single administration of these secretagogues, with the exception of the LH response, which is lower in the CAP test than after single GnRH administration.     

Dermatitis associated with Dirofilaria repens microfilariae in three dogs in Saudi Arabia

The presence of microfilariae of the zoonotic nematode Dirofilaria repens is reported in three dogs from Saudi Arabia, manifesting as pruritic dermatitis with signs including erythema, alopecia, papules, crusting and hyperkeratosis. All dogs were found to have concurrent babesiosis. Specific treatments against the two conditions led to complete clinical recovery and disappearance of microfilariae from the blood one month later.     

Transsphenoidal hypophysectomy for four dogs with pituitary ACTH-producing adenoma

Four dogs diagnosed as pituitary-dependent hyperadrenocorticism were treated with transsphenoidal hypophysectomy and postoperative hormone supplementation therapy. On histological examination of the resected tissues, the tumors were ACTH-producing adenoma of the anterior lobe. Clinical signs such as alopecia and calcinosis cutis, as well as endocrinological abnormalities, were markedly alleviated after surgery. The clinical courses of these 4 dogs suggest that transsphenoidal hypophysectomy may be a useful treatment for pituitary-dependent hyperadrenocorticism.     

Secretion of sex hormones in dogs with adrenal dysfunction

OBJECTIVE: To evaluate adrenal sex hormone concentrations in response to ACTH stimulation in healthy dogs, dogs with adrenal tumors, and dogs with pituitary-dependent hyperadrenocorticism (PDH). DESIGN: Prospective study. ANIMALS: 11 healthy control dogs, 9 dogs with adrenal-dependent hyperadrenocorticism (adenocarcinoma [ACA] or other tumor); 11 dogs with PDH, and 6 dogs with noncortisol-secreting adrenal tumors (ATs). PROCEDURE: Hyperadrenocorticism was diagnosed on the basis of clinical signs; physical examination findings; and results of ACTH stimulation test, low-dose dexamethasone suppression test, or both. Dogs with noncortisol-secreting ATs did not have hyperadrenocorticism but had ultrasonographic evidence of an AT. Concentrations of cortisol, androstenedione, estradiol, progesterone, testosterone, and 17-hydroxyprogesterone were measured before and 1 hour after i.m. administration of 0.25 mg of synthetic ACTH. RESULTS: All dogs with ACA, 10 dogs with PDH, and 4 dogs with ATs had 1 or more sex hormone concentrations greater than the reference range after ACTH stimulation. The absolute difference for progesterone, 17-hydroxyprogesterone, and testosterone concentrations (value obtained after ACTH administration minus value obtained before ACTH administration) was significantly greater for dogs with ACA, compared with the other 3 groups. The absolute difference for androstenedione was significantly greater for dogs with ACA, compared with dogs with AT and healthy control dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Dogs with ACA secrete increased concentrations of adrenal sex hormones, compared with dogs with PDH, noncortisol-secreting ATs, and healthy dogs. Dogs with noncortisol-secreting ATs also have increased concentrations of sex hormones. There is great interdog variability in sex hormone concentrations in dogs with ACA after stimulation with ACTH.     

A randomized comparative clinical trial of recombinant canine interferon-gamma (KT-100) in atopic dogs using antihistamine as control

Recombinant canine interferon-gamma (KT-100) or topical antihistamine (diphenhydramine: DH) was administered to dogs with atopic dermatitis (AD) for 4 weeks and their efficacies were compared using pruritus, excoriation, erythema and alopecia as evaluation criteria. Clinical studies on 92 atopic dogs (KT-100 group: 63, DH group: 29) were conducted at 18 animal hospitals in Japan. KT-100 was administered subcutaneously once a day three times a week on alternating days for 4 weeks. DH was administered topically twice daily for 4 weeks. The efficacy rates of the KT-100 group on day 28 were 72.1% for pruritus, 73.8% for excoriation, 75.4% for erythema and 60.7% for alopecia, which were significantly higher than those of the DH group (20.7% for pruritus, 27.6% for excoriation, 24.1% for erythema and 24.1% for alopecia).     

Hormonal abnormalities in Pomeranians with normal coat and in Pomeranians with growth hormone-responsive dermatosis

Clinical status, skin biopsy specimens, and endocrine function were evaluated in normal-coated Pomeranians (n = 12) and Pomeranians affected with growth hormone (GH)-responsive dermatosis (n = 7), then were compared with values in mixed-breed dog controls (n = 19). All Pomeranians were clinically normal; however, the Pomeranians with GH-responsive dermatosis had bilateral alopecia and hyperpigmentation of the trunk, caudal portion of the thighs, and ventral neck region. Skin biopsy specimens from the affected Pomeranians had decreased-to-normal epidermal thickness and follicular atrophy, compared with normal-coated Pomeranians. Numerous elastin fibers were observed in the skin biopsy specimens of unaffected and affected Pomeranians. Both groups of Pomeranians had normal results of thyrotropin-releasing hormone (TRH) and thyrotropin (TSH) response, adrenocorticotropin (ACTH) stimulation, and dexamethasone suppression testing. There was no significant increase in serum GH concentration in either group of Pomeranians after xylazine or human GH-releasing factor (GHRF) administration, whereas control dogs had significant (P less than or equal to 0.05) increase in serum GH concentration after administration of either agent. Baseline plasma ACTH concentration in unaffected and affected Pomeranians was increased above the normal range (40 to 90 pg/ml). Post-ACTH administration serum progesterone, 17-hydroxyprogesterone, and androgen (dehydroepiandrosterone sulfate or androstenedione) concentrations were consistently high in unaffected and affected Pomeranians, compared with values in control dogs.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ghrelin-stimulation test in the diagnosis of canine pituitary dwarfism

This study investigated whether ghrelin, a potent releaser of growth hormone (GH) secretion, is a valuable tool in the diagnosis of canine pituitary dwarfism. The effect of intravenous administration of ghrelin on the release of GH and other adenohypophyseal hormones was investigated in German shepherd dogs with congenital combined pituitary hormone deficiency and in healthy Beagles. Analysis of the maximal increment (i.e. difference between pre- and maximal post-ghrelin plasma hormone concentration) indicated that the GH response was significantly lower in the dwarf dogs compared with the healthy dogs. In none of the pituitary dwarfs, the ghrelin-induced plasma GH concentration exceeded 5 microg/l at any time. However, this was also true for 3 healthy dogs. In all dogs, ghrelin administration did not affect the plasma concentrations of ACTH, cortisol, TSH, LH and PRL . Thus, while a ghrelin-induced plasma GH concentration above 5 microg/l excludes GH deficiency, false-negative results may occur.