Pituitary tumour shrinkage and diabetic remission in two cats with Cushing syndrome treated with cabergoline.

Cabergoline may reduce pituitary tumor size and achieve diabetic remission in cats with pituitary-dependent hypercortisolism.

This case series describes two diabetic cats with pituitary-dependent hypercortisolism (PDH) treated with the dopamine agonist cabergoline. Both cats presented with concurrent diabetes mellitus managed initially with insulin glargine, continuous glucose monitoring, and nutritional therapy. Hypercortisolism was diagnosed based on clinical signs, failed low-dose dexamethasone suppression testing, elevated endogenous ACTH concentrations, and pituitary enlargement confirmed via computed tomography. Cabergoline was initiated at 10 µg/kg orally every 48 hours, with the dose escalated in Case 2 to 10 µg/kg every 12 hours due to insufficient response. Both cats achieved diabetic remission, at 1 and 6 months respectively, suggesting successful reduction in cortisol-mediated insulin resistance. Serial monitoring over 8 months demonstrated declining endogenous ACTH concentrations and meaningful reductions in pituitary tumor volume—29% in Case 1 and 52% in Case 2—indicating a direct anti-tumoral effect. Cabergoline, a dopamine D2 receptor agonist, is hypothesized to suppress ACTH secretion from corticotroph adenomas via dopaminergic pathways. This is clinically significant as medical treatment options for feline PDH are limited; trilostane and mitotane are commonly used adrenal-targeting agents, but a pituitary-directed therapy offering tumor shrinkage represents a potentially superior approach. These findings, while preliminary given the small case number, support cabergoline as a promising medical option for feline PDH warranting further investigation in larger prospective studies.

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