Case summary A 7-month-old domestic shorthair cat was presented for evaluation of stunted growth, recurrent hypoglycaemia during the first months of its life and altered mentation. Complete blood count and biochemistry were unremarkable, except for mildly elevated serum creatinine concentration (despite low muscle mass) and concurrent isosthenuria. Hyposomatotropism was diagnosed based on persistent low circulating insulin-like growth factor 1 concentrations and a lack of response of circulating growth hormone (GH) concentration after the administration of GH-releasing hormone. Other endocrinopathies such as hypothyroidism and hypoadrenocorticism were excluded. MRI of the brain revealed a fluid-filled empty sella tursica, consistent with a pituitary cyst and atrophy/hypoplasia of the pituitary. Echocardiography was unremarkable at the time of diagnosis of hyposomatotropism. Three months later, ovariohysterectomy revealed immature ovaries, raising the suspicion of luteinising and follicle-stimulating hormone deficiency. At 1 year of age, the cat developed congestive heart failure secondarily to dilated cardiomyopathy (DCM) with severely reduced left ventricular systolic function and died a few days later. Pathology showed atrophy of the adenohypophysis, epithelial delineation of the pituitary cysts, mild cardiomegaly, multifocal fibrosis of the left ventricle and a mild, multifocal, chronic epicarditis.

Relevance and novel information GH deficiency is a very rare endocrinopathy in cats. This is the first case to describe the development of DCM with concurrent hyposomatotropism, which has previously been reported in human medicine. Other notable abnormalities that could be related to GH deficiency are juvenile self-limiting hypoglycaemia, behavioural changes and possible nephropathy.