Endocrine Abstracts

Background: Acromegaly is a rare disorder associated with excessive levels of growth hormone(GH) and insulin-like growth factor-1(IGF-1). GH/IGF-1 excess leads to morphologic craniofacial and acral changes as well as cardiometabolic complications, but the phenotypic changes and presentation differ across species.

Aim: To present the resemblances and distinctive features of acromegaly in humans, cats and dogs.

Methods: A literature review of the epidemiology, pathophysiology, clinical features, diagnosis and management of acromegaly in humans, cats and dogs was performed by doctors and veterinaries specialized in Endocrinology. The key aspects of each species were summarized and compared.

Results and conclusion: Acromegaly is associated with prominent craniofacial changes: frontal bossing, enlarged nose, ears and lips are typical in humans; increased width of the head and skull enlargement are common in cats; dogs may present with exophthalmos. Malocclusion, prognathism, dental diastema and upper airway obstruction may occur in the three species, as well as growth and widening of extremities resulting in osteoarticular compromise. Increase of articular joint cartilage thickness, vertebral fractures and spine malalignment is more evident in humans, while arthropathy and spondylosis deformans may occur in cats. Organomegaly, heart failure, ventricular hypertrophy, and an increased cardiometabolic risk is observed in humans and cats. Diabetes may be present in humans, cats and dogs. In GH-secreting pituitary tumours, local compressive effects and behavioral changes are mostly observed in humans, but may also affect cats. Being particularly rare in dogs, hypersomatotrophism may occur due to GH hypersecretion in mammary glands, primary hypothyroidism or, extremely uncommon in this species, due to a GH-secreting pituitary adenoma. Cutis verticis gyrata and skin tags are exclusively found in humans, palmigrade/plantigrade stance is sometimes observed in acromegalic cats, while dogs can present with excessive skin folds and coat thickening. Serum IGF-1 is used for acromegaly diagnosis in humans, cats and dogs, but oral glucose tolerance test with GH measurement is only useful in humans and dogs. Imaging studies are performed after biochemical diagnosis of acromegaly. Hypophysectomy is the first line treatment in humans and cats, although not always available in veterinary medicine. In dogs, GH-secreting mammary tumours may require surgery, while radiotherapy and pasireotide have been successfully used for pituitary adenomas. In conclusion, GH-secreting pituitary tumours are the main cause of acromegaly in humans and cats, but they rarely occur in dogs. Substantial acromegalic similarities are present across the species, however there are few species-specific features and management particularities can be found.