Effect of hyperadrenocorticism on ultrasonographic findings in prostate and testicles of aged dogs

Introduction and aim. The main causes of hyperadrenocorticism (HAC) in the dog are an excessive secretion of ACTH, a functional adrenal tumor, or the administration of glucocorticoid drugs (1). An increased concentration of glucocorticoids is involved in the suppression of reproductive functions because of the interaction of hypothalamic-pituitary-adrenal and -gonadal axes (1). It has been proved that the experimental administration of glucocorticoids results in a decreased concentrations of testicular androgens (2). Endocrinological disorders, as HAC, or long-term exposure to androgens, as ageing, influence the morphological and functional status of testicles and prostate. For instance, in case of HAC a testicular atrophy has been described whereas in old dogs a common finding is the benign prostatic hyperplasia (BPH) (1,3,4). The aim of the present study was to evaluate the effect of HAC on ultrasonographic findings in prostate and testicles of aged dogs. Materials and methods. Twenty-five intact aged dogs (10 to 16 years) with non-iatrogenic HAC were included in this study. The HAC diagnosis was performed by low-dose dexamethasone suppression test combined with urine cortisol:creatinine ratio (5). Clinical soundness examination and ultrasonography evaluation (8C-RS 6-10MHz probe, Vivid i, GE Medical Systems Israel Ltd, Tirat Carmel, Israel) of prostate and testicles were performed in all dogs. Prostatic and testicular volume was estimated using the ellipsoid formula L x W x H x 0.523 (6) and compared with normal values for different body weights as described in the literature (4,7,8). Data were analyzed by Chi Square test and significance was set at p<0.05. Results. In 56% of the dogs prostate was of normal dimensions and this proportion was similar to that of dogs with atrophic gland (36% p>0.05), but significantly higher than that of dogs with enlarged gland (8%; p<0.001). Only endoprostatic cysts smaller than 1 cm in diameter were observed in 35.7% (5/14) of dogs with prostate of normal size, in 22.2% (2/9) of dogs with small prostate and in all dogs with enlarged prostate. In the majority of the dogs (64%) both testicles were normal, whereas in the remaining 36% (p<0.05) testicles were altered in size and/or echotexture. Conclusions. Hyperadrenocorticism is more frequent in middle-aged to old dogs (1) and 95% of dogs older than 9.5 years are affected by BPH (3). In old dogs a senile involution of the gland is also reported (9). It remains to elucidate whether in case of HAC the low testosterone concentration due to cortisol negative feedback on FSH and LH secretion might be associated with a lower incidence of prostatomegaly and of large endoprostatic cysts as suggested by the present data. The majority of the dogs examined in this study were not affected by testicular atrophy, a sign associated with HAC (1). References. 1) Feldman and Nelson. Canine and Feline Endocrinology and Reproduction, 1987; WB Saunders, Philadelphia. 2) Kemppainen et al. J Endocrinol, 1983;96:293-302. 3) Zirkin and Strandberg. Anat Rec, 1984;208:207-14. 4) Lowseth et al. Vet Pathol, 1990;27:347-53. 5) Rijnberk and Kooistra. Glucocorticoid excess. In Clinical Endocrinology of Dogs and Cats, 2010; Schlutersche Verlagsgesellschaft mbH & Co. KG, Hannover. 6) Gouletsou et al. Anim Reprod Sci, 2008;108:1-12. 7) Eilts et al. Theriogenology, 1993;40:819-28. 8) Ruel et al. Vet Radiol Ultrasound, 1998;39:212-6. 9) Johnston et al. Canine and Feline Theriogenology, 2001; WB Saunders, Philadelphia.