Pituitary tumours are one of the most common form of intracranial tumour in humans, affecting as many as 1 in 6 of us in our lifetimes. Despite this, biological models in which to examine their biology and aetiology have remained difficult to establish, and those that exist do not faithfully phenocopy these disorders in humans. We have taken advantage of spontaneously occurring pituitary tumours in the domestic cat population (Felis catus), to examine somatotrope-derived tumours that cause hypersomatotropism (HST ; feline acromegaly). Current estimates indicate that incidence of acromegaly in cats is almost ten times greater than that in humans, yet very little has been described about a condition that is probably under-reported. We have used a histological, molecular, environmental and genetic analyses to examine pituitary tumours obtained from feline patients undergoing hypophysectomy. Pituitary tumour tissue from feline patients was strongly positive for GH, but not PRL ; histologically, abnormal acini structure were observed with reticulin staining. Multiplex RT-qPCR revealed elevated expression of SSTR1, SSTR2 and SSTR5 in feline acromegalics, and medical management of feline acromegaly patients with pasireotide resulted in promising reductions in serum IGF-1 levels, whereas cabergoline was less effective. From a genetic perspective, SNPs in the AIP gene may represent a potential factor in the development of acromegly in cats. Finally, higher concentrations of some organohalogenated compounds (known EDCs) were found in plasma from feline acromegaly patients compared with healthy controls, suggesting a role for EDCs in disease susceptibility. Therefore, cats may well act as sentinel species for acromegaly.