Spontaneous acromegaly: a retrospective case control study in German shepherd dogs

Acromegaly results from the overproduction of growth hormone in adulthood and is characterised by overgrowth of soft tissue and/or bone as well as insulin resistance. There are few data indicating the risk factors associated with this disease in dogs or its clinicopathological features and sequelae. The objective of this retrospective study was to catalogue and assess these aspects of the disease in German shepherd dogs (GSDs) which were found to be over-represented among acromegalic dogs attending two veterinary referral clinics over a period of 7 years. Each acromegalic dog (AD) was compared with two breed/age/sex matched controls. Clinical signs of acromegaly included panting, polyuria/polydipsia, widened interdental spaces, weakness, inspiratory stridor, macroglossia, weight gain, redundant skin folds, thick coat, exophthalmos and mammary masses. Serum alkaline phosphatase, creatine-kinase, glucose, triglyceride, phosphate ion, and 'calcium per phosphate product' concentrations were significantly higher in acromegalic animals while haemoglobin concentration, blood urea nitrogen, sodium and chloride ion concentrations, and urinary specific gravity, osmolality and fractional excretion of phosphate were significantly lower. Although, in the majority of cases clinicopathological abnormalities resolved following ovariohysterectomy, in one dog, acromegalic signs abated and insulin-like growth factor-1 concentrations normalised only following the surgical excision of mammary tumours carried out 2 months after ovariohysterectomy. The findings of this study indicate that GSDs are predisposed to the development of acromegaly with a suspected inherited susceptibility.