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Abstract

Objective—To evaluate the effect of a soy-based diet on general health and adrenocortical and thyroid gland function in dogs.

Animals—20 healthy privately owned adult dogs.

Procedures—In a randomized controlled clinical trial, dogs were fed a soy-based diet with high (HID; n = 10) or low (LID; 10) isoflavones content. General health of dogs, clinicopathologic variables, and serum concentrations of adrenal gland and thyroid gland hormones were assessed before treatment was initiated and up to 1 year later. Differences between groups with respect to changes in the values of variables after treatment were assessed by means of a Student t test (2 time points) and repeated-measures ANOVA (3 time points).

Results—No differences were detected between the 2 groups with respect to body condition and results of hematologic, serum biochemical, and urine analyses. Most serum concentrations of hormones did not change significantly after treatment, nor were they affected by diet. However, the mean change in serum concentration of total thyroxine was higher in the HID group (15.7 pmol/L) than that in the LID group (–1.9 pmol/L). The mean change in estradiol concentration after ACTH stimulation at 1 year after diets began was also higher in the HID group (19.0 pg/mL) than that in the LID group (–5.6 pg/mL).

Conclusions and Clinical Relevance—Phytoestrogens may influence endocrine function in dogs. Feeding soy to dogs on a long-term basis may influence results of studies in which endocrine function is evaluated, although larger studies are needed to confirm this supposition.

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in American Journal of Veterinary Research

Abstract

Objective—To determine causes of hyperphosphatasemia (high serum alkaline phosphatase [ALP] activity) in apparently healthy Scottish Terriers.

Design—Prospective case-controlled study.

Animals—34 apparently healthy adult Scottish Terriers (17 with and 17 without hyperphosphatasemia).

Procedures—Serum activities for 3 isoforms (bone, liver, and corticosteroid) of ALP were measured. Concentrations of cortisol, progesterone, 17-hydroxyprogesterone, androstenedione, estradiol, and aldosterone were measured before and after cosyntropin administration (ie, ACTH; 5 μg/kg [2.27 μg/lb], IM). Liver biopsy specimens from 16 dogs (11 with and 5 without hyperphosphatasemia) were evaluated histologically.

Results—In dogs with hyperphosphatasemia, the corticosteroid ALP isoform comprised a significantly higher percentage of total ALP activity, compared with the percentage in dogs without hyperphosphatasemia (mean ± SE, 69 ± 5.0% and 17 ± 3.8%, respectively). In 6 dogs with hyperphosphatasemia, but none without, serum cortisol concentrations exceeded reference intervals after ACTH stimulation. Six dogs with and 15 without hyperphosphatasemia had increased concentrations of ≥ 1 noncortisol steroid hormone after ACTH stimulation. Serum ALP activity was correlated with cortisol and androstenedione concentrations (r = 0.337 and 0.496, respectively) measured after ACTH stimulation. All dogs with and most without hyperphosphatasemia had abnormal hepatocellular reticulation typical of vacuolar hepatopathy. Subjectively, hepatocellular reticulation was more severe and widespread in hyperphosphatasemic dogs, compared with that in nonhyperphosphatasemic dogs.

Conclusions and Clinical Relevance—Hyperphosphatasemia in apparently healthy Scottish Terriers was most likely attributable to hyperadrenocorticism on the basis of exaggerated serum biochemical responses to ACTH administration and histologic hepatic changes, but none of the dogs had clinical signs of hyperadrenocorticism.

Full access
in Journal of the American Veterinary Medical Association

Abstract

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 IM 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. (J Am Vet Med Assoc 2005;226:556–561)

Full access
in Journal of the American Veterinary Medical Association