An older dog that drinks constantly, urinates indoors or overnight, eats everything in sight, and yet is slowly losing muscle and growing a round belly is one of the most common patients in small animal practice. Cushing’s syndrome — chronic cortisol excess — typically appears in middle-aged and older dogs. The average patient is about 11 years old, and roughly three quarters weigh under 20 kg, which is why small breeds such as poodles, dachshunds, boxers, and beagles are over-represented.
What Too Much Cortisol Actually Does
Cortisol is a normal stress hormone; in excess it becomes destructive. It breaks down muscle and connective tissue, thins the skin, suppresses the immune system, and redistributes fat to the belly. In 80 to 85 percent of spontaneous cases the trigger is a tiny pituitary tumor pumping out ACTH (pituitary-dependent disease). The remaining 15 to 20 percent come from a tumor in one adrenal gland itself. A third form is iatrogenic: long-term steroid treatment for allergies or arthritis can produce identical signs.
The Signs Form a Pattern
Vets summarize the classic picture as the “P” signs, and owners usually notice several at once rather than all of them.
| Sign | What you actually notice |
|---|---|
| Polydipsia | The water bowl empties; refilling it far more often than usual |
| Polyuria | Indoor accidents or waking you at night to go out |
| Polyphagia | Constant hunger, begging, raiding bins; appetite never drops |
| Pendulous abdomen | A sagging, pot-bellied look from weak muscles and shifted fat |
| Panting | Heavy panting even at rest; poor exercise tolerance |
| Alopecia and thin skin | Bilateral, non-itchy hair loss on the trunk; fragile skin |
None of these signs is unique to Cushing’s, and dogs are being diagnosed earlier in the disease than they used to be, so a partial picture is common.
Why Confirmation Takes More Than One Test
There is no single test that reliably confirms or excludes the disease. Routine bloodwork usually shows a stress leukogram, raised alkaline phosphatase, and a dilute urine. The current ACVIM consensus treats the low-dose dexamethasone suppression test as the screening choice, with the ACTH stimulation test preferred when another illness is present. Both can produce false results, which is why vets combine suggestive signs, labwork, endocrine testing, and often abdominal ultrasound to separate the pituitary form from the adrenal form. If suspicion is strong and the first tests are negative, retesting in three to six months is standard.
Treatment and What to Expect
The first-line drug for most dogs is trilostane, given daily for life. Thirst and appetite often improve within days, while the coat takes months. Roughly 15 percent of dogs have side effects, usually digestive or lethargy, so monitoring bloodwork follows a set schedule. Adrenal tumors can sometimes be removed surgically, though that surgery is demanding. Dogs rarely die of Cushing’s itself; treated dogs commonly live well, with reported median survival of up to about 30 months for the pituitary form, and many live comfortably far longer.
The takeaway. A dog showing several of the “P” signs deserves bloodwork, not watchful waiting. This article is background information, not veterinary advice; diagnosis and dosing belong to your vet, and untreated dogs are prone to diabetes and urinary infections on top of everything else.