Cushing's disease
Overproduction of cortisol (the body's stress hormone), most commonly in older dogs. Causes increased thirst, urination, appetite, and a pot belly.
Cushing's disease (hyperadrenocorticism) is one of the more common endocrine conditions in middle-aged and senior dogs. It results from too much cortisol — either from a small pituitary tumour stimulating the adrenals (most common, ~85% of cases) or directly from an adrenal tumour.
Classic signs: increased thirst and urination, increased appetite, pot-bellied appearance, thin skin, hair thinning or loss on the body (often symmetrical), panting at rest, exercise intolerance, recurring skin or urinary infections.
Diagnosis involves blood tests (low-dose dexamethasone suppression test or ACTH stimulation test) and abdominal ultrasound. Treatment is medical (trilostane or mitotane) and lifelong, with regular monitoring.
Cushing's is rarely an emergency on its own, but it predisposes to other problems: diabetes, blood clots, hypertension, infections. Diagnosis and treatment improve quality of life substantially in most affected dogs.