Cushing’s disease affects roughly 1 to 3 out of every 1,000 dogs seen by a veterinarian, making it one of the more common hormonal disorders in dogs but still relatively uncommon overall. A large UK study of dogs in primary-care veterinary practices estimated a one-year prevalence of 0.17% and found that about 0.06% of dogs receive a new diagnosis each year. Other studies place the figure slightly higher, between 0.20% and 0.28% of dogs attending veterinary practices.
Those numbers might sound small, but Cushing’s is one of the most frequently diagnosed endocrine conditions in dogs, alongside diabetes and thyroid disease. If your vet has raised Cushing’s as a possibility, here’s what the data says about who gets it, what it looks like, and what to expect.
What Cushing’s Disease Actually Is
Cushing’s disease (formally called hyperadrenocorticism) happens when a dog’s body produces too much cortisol, the hormone that manages stress, metabolism, and immune function. A small, steady excess of cortisol over months or years gradually changes how the body handles water, fat, muscle, and skin. The result is a cluster of symptoms that often get mistaken for normal aging.
About 85% of naturally occurring cases are pituitary-dependent, meaning a tiny tumor on the pituitary gland (at the base of the brain) signals the adrenal glands to overproduce cortisol. The remaining 15% are caused by a tumor on one of the adrenal glands themselves. There is also an extremely rare atypical form, but it accounts for a very small fraction of cases.
Which Dogs Are Most at Risk
Cushing’s is overwhelmingly a disease of middle-aged and older dogs. In pituitary-dependent cases, the typical age at diagnosis falls between 7 and 9 years, though dogs as young as 2 have been diagnosed. Dogs with adrenal tumors tend to be older still, with a median diagnosis age of 10 to 11 years. It’s rare in dogs under 6.
Certain breeds show up more often in studies. Poodles, Dachshunds, Boston Terriers, Boxers, and various terrier breeds have been consistently identified as higher-risk. Small to medium breeds appear overrepresented, though any breed can develop the condition. There is no strong sex predisposition for the pituitary form, although adrenal tumors may occur somewhat more frequently in females.
Signs That Prompt Testing
The classic signs of Cushing’s tend to come on slowly, which is one reason the disease is often caught late. The most recognizable combination includes increased thirst and urination, a noticeably bigger appetite, a pot-bellied appearance, and thinning hair or skin changes. Many owners initially attribute these to aging, especially in breeds that naturally slow down in their senior years.
Skin problems are common: thin, fragile skin, hair loss that’s symmetrical on both sides of the body, or dark patches of pigmentation. Some dogs develop recurrent skin or urinary tract infections because excess cortisol suppresses the immune system. Panting, lethargy, and muscle weakness round out the picture. A dog doesn’t need to show every sign, but current veterinary guidelines recommend testing only when two or more of these signs are present together.
How Diagnosis Works
There is no single perfect test for Cushing’s. All available tests can produce false positives, especially in dogs that are stressed or dealing with another illness at the same time. This is why vets are advised to test only when clinical suspicion is already high based on symptoms and basic bloodwork.
The most commonly used screening test measures how a dog’s cortisol levels respond to a small dose of a synthetic steroid given by injection. If cortisol stays elevated after eight hours, that’s consistent with Cushing’s. An alternative test stimulates the adrenal glands directly and checks whether cortisol spikes above a threshold. A urine test that compares cortisol to creatinine is highly sensitive, meaning a normal result reliably rules Cushing’s out, but an abnormal result doesn’t confirm it because many other conditions can push that ratio up.
Once Cushing’s is confirmed, further testing (usually an abdominal ultrasound) helps determine whether the problem originates from the pituitary gland or an adrenal tumor, since the treatment approach differs.
Treatment and What to Expect
Most dogs with Cushing’s are managed with daily medication that reduces cortisol production. The goal isn’t a cure but a return to more normal cortisol levels, which improves thirst, energy, skin health, and overall comfort. Dogs on medication need regular blood tests, especially in the first few months, to make sure cortisol drops into the right range without going too low.
For adrenal tumors, surgery to remove the affected gland is sometimes an option, though it carries significant risk and is typically performed at specialty hospitals. Many adrenal cases are also managed medically.
Response to treatment varies. Most owners notice improvements in water intake and energy within the first few weeks. Skin and coat changes take longer, often several months. Some dogs do remarkably well for years on medication.
Survival After Diagnosis
A study of 219 dogs diagnosed with Cushing’s in English primary-care practices found a median survival time of 510 days (roughly a year and a half) from first diagnosis. About 60% of dogs survived at least one year, and 35% were still alive at the two-year mark. Dogs treated at referral (specialty) hospitals tended to do better, with median survival times ranging from roughly 22 months to two and a half years for pituitary-dependent cases.
These numbers reflect the reality that Cushing’s is typically diagnosed in older dogs who may have other age-related health issues. The disease itself progresses slowly, and many dogs maintain a good quality of life for a meaningful period with proper management. Dogs with adrenal tumors in referral settings had median survival times between roughly one year and 16 months, partly because some of those tumors are malignant.
It’s worth noting that untreated dogs in the study had a median survival of only about 178 days, though that group was small and likely included dogs too sick for treatment. The data overall supports that medical management extends both lifespan and comfort for most dogs.
Why It Often Gets Caught Late
Because the signs overlap so heavily with normal aging, Cushing’s is frequently underdiagnosed or diagnosed well after symptoms begin. A dog drinking more water and losing some muscle tone at age 10 doesn’t immediately alarm most owners. Routine bloodwork may show mildly elevated liver enzymes or dilute urine, subtle clues that prompt further investigation only if the vet is already thinking about Cushing’s. The slow onset also means the 0.17% prevalence figure likely underestimates the true number of affected dogs, as some cases are never formally diagnosed.