Feline Acromegaly Study Guide

Overview and Clinical Importance

Feline acromegaly (also known as hypersomatotropism) is an endocrine disorder caused by chronic excessive secretion of growth hormone (GH) from a functional pituitary adenoma. This condition has emerged as a critically important differential diagnosis for difficult-to-regulate diabetic cats and represents a significant topic on the NAVLE examination.

Recent studies have revealed that acromegaly affects approximately 25-32% of diabetic cats, making it far more common than previously recognized. The disease is caused by a GH-secreting adenoma of the anterior pituitary (pars distalis), which leads to insulin resistance, diabetes mellitus, and characteristic soft tissue and skeletal changes.

Etiology and Pathophysiology

Cause of Feline Acromegaly

The predominant cause of feline acromegaly is a functional somatotropic adenoma (acidophil adenoma) in the pars distalis of the anterior pituitary gland. These tumors grow slowly and may be present for a prolonged period before clinical signs become apparent. Rarely, somatotropic hyperplasia may be the underlying cause. Unlike dogs, where acromegaly is typically caused by progestogen-induced mammary GH secretion during diestrus, feline acromegaly is almost exclusively pituitary in origin.