Weight Loss in Dogs With Cushing's Disease: What It Means
By Dr. Zubair Khalid, DVM, MS, PhD ·
Weight loss in dogs with Cushing's is uncommon because excess cortisol usually drives weight gain, so a shrinking dog often points to a second problem or a treatment that has gone too far. The most common explanations are uncontrolled diabetes, chronic kidney or heart disease, cancer, or a trilostane dose that has pushed cortisol too low. This article is educational and is not a substitute for veterinary diagnosis or treatment.
Quick Answer
- Cushing's disease usually causes weight gain, a potbelly, and muscle wasting, so visible weight loss is a signal to investigate, not a sign the disease is improving [1][2].
- The most urgent rule-out is diabetes mellitus, which commonly occurs alongside Cushing's and causes weight loss despite a good or increased appetite [2].
- If your dog is on trilostane and has lost weight, the dose may now be too high for its new body weight, and cortisol can drop too low.
- Weigh your dog monthly on the same scale and bring a written log to every recheck.
- Call your veterinarian promptly for any weight loss, and seek emergency care for vomiting, collapse, or a dog that will not eat.
What Cushing's Disease Is, in Plain Words
Cushing's syndrome is any condition where the body is exposed to too much cortisol, the main stress hormone [2]. In dogs, the most common form is pituitary-dependent hyperadrenocorticism, also called Cushing's disease, which accounts for 80% to 85% of reported cases [2]. It happens when a small tumor in the pituitary gland makes too much ACTH, the hormone that tells the adrenal glands to produce cortisol [1].
A less common form starts with a tumor in an adrenal gland that secretes cortisol on its own [2]. Rarer causes include ectopic ACTH secretion, episodic Cushing's disease, meal-induced hypercortisolemia, and occult or atypical hyperadrenocorticism [2]. The type matters because treatment differs. You can read more about the differences in our guide to Cushing's disease in dogs: pituitary vs adrenal hyperadrenocorticism.
Signs Owners Notice, and Where Weight Fits In
Classic Cushing's signs include drinking and urinating more, a ravenous appetite, a pendulous abdomen, panting, muscle wasting, and skin and coat changes [2]. Muscle wasting is easy to mistake for weight loss. A dog can look thinner over the spine and temples while actually carrying extra fat in the belly.
True weight loss is different. The number on the scale drops. Ribs and hip bones become easier to feel. You may notice it before your veterinarian does.
Other signs that often travel with weight loss include:
- Increased appetite with a falling weight (a strong hint toward diabetes)
- Decreased appetite, which is not typical of Cushing's itself
- Vomiting, diarrhea, or both
- Weakness, reluctance to climb stairs, or exercise intolerance
- Increased thirst that never settles
If weight loss is your main concern and you are not sure whether Cushing's is involved, our article on why your dog is losing weight walks through the general causes.
Why Weight Loss Happens in a Disease That Usually Causes Weight Gain
Diabetes mellitus
Diabetes is the first thing most veterinarians check. Excess cortisol raises blood sugar and works against insulin, and diabetes is a well-recognized companion condition in dogs with hyperadrenocorticism [2]. A diabetic dog loses weight even while eating well because sugar leaves the body in the urine instead of feeding the tissues.
A trilostane dose that is now too high
Trilostane is the standard medical treatment for pituitary-dependent hypercortisolism in dogs [3]. Doses are calculated from body weight, so a dog that has lost several pounds may now be over-dosed. Too little cortisol causes vomiting, diarrhea, lethargy, and poor appetite, and that combination drives further weight loss. This is a medical problem that needs a recheck and a dose adjustment, not a wait-and-see approach.
Other diseases happening at the same time
Older dogs collect problems. Chronic kidney disease, heart disease, dental disease, inflammatory bowel disease, and cancer can all cause weight loss and can all appear alongside Cushing's. Some dogs with hypercortisolism also develop heart changes. A recent pilot study found that dogs with both hyperadrenocorticism and myxomatous mitral valve disease had higher urinary normetanephrine to creatinine ratios than dogs with valve disease alone, suggesting extra stress on the heart when the two conditions overlap [4].
Muscle loss instead of fat loss
Cortisol breaks down muscle protein. A dog can lose real muscle mass and still gain fat, which is why body condition scoring matters more than the scale alone. If your dog's spine and hind legs look bony but the belly is round, that is muscle wasting, not true weight loss.
Poor response to treatment
Some dogs simply do not respond well to trilostane. In one study of 23 dogs with pituitary-dependent hypercortisolism, 8 were classified as nonresponders after 4 to 8 months of treatment [3]. Nonresponders had higher baseline ALT, higher endogenous ACTH, higher pre-ACTH cortisol, and more frequent bilateral adrenal enlargement than good responders [3]. If your dog is losing weight while on treatment, poor control is one possibility your veterinarian will consider.
Causes and Risk Factors
| Factor | What it means for your dog |
|---|---|
| Diabetes mellitus | Common companion disease, causes weight loss with a good appetite [2] |
| Trilostane dose too high | Weight loss changes the correct dose, cortisol can fall too low [3] |
| Concurrent kidney, heart, or GI disease | Adds its own weight loss on top of Cushing's |
| Cancer | Any unexplained weight loss in a senior dog deserves screening |
| Muscle wasting from cortisol | Looks like weight loss but is loss of muscle, not fat [2] |
| Poor trilostane response | Higher baseline ALT, ACTH, and cortisol, plus bilateral adrenal enlargement [3] |
| Pituitary macrotumor | More likely in dogs diagnosed at 10.9 years or younger, French Bulldogs, and dogs with neurologic signs [5] |
Cushing's disease itself is most often diagnosed in middle-aged to older dogs [1]. A pituitary tumor that grows large enough to press on the brain is called a macrotumor, and risk factors include being diagnosed at 10.9 years of age or younger, being a French Bulldog, and having neurologic signs [5]. Weight loss is not listed as a classic sign of macrotumor, but neurologic changes such as circling, head pressing, or behavior shifts are. Our article on Cushing's disease dog behavior problems covers those signs in more detail.
How Veterinarians Sort This Out
Your veterinarian starts with history and a full physical exam, including a body condition score and a muscle condition score [2]. Expect a weight trend, not a single number.
Baseline testing usually includes a complete blood count, chemistry panel, and urinalysis [2]. These tests can reveal high blood sugar, dilute urine, raised liver enzymes, or protein loss. A urine cortisol to creatinine ratio, an ACTH stimulation test, or a low-dose dexamethasone suppression test confirms hyperadrenocorticism [1]. Your veterinarian will also test for diabetes and may recommend imaging of the abdomen or pituitary [2].
If your dog is already on trilostane and losing weight, the plan changes. Your veterinarian will likely recheck cortisol levels, review the dose against the current weight, and look for a second disease. Be honest about appetite, water intake, stool quality, and energy at home. Those details often point to the answer faster than any single test.
Treatment Options
Treatment depends on what is actually causing the weight loss.
For Cushing's disease itself, options include medical treatment with adrenocortical suppressants, radiation, and surgery [1]. Trilostane is the treatment of choice for pituitary-dependent hypercortisolism in dogs [3]. Your veterinarian calculates the dose from your dog's current weight and health, then adjusts it based on recheck results. Never change the dose on your own.
For diabetes, treatment means insulin plus a consistent diet and schedule. Your veterinarian sets the insulin type and dose for your individual dog.
For a trilostane overdose, treatment usually means stopping the drug, supportive care, and possibly a glucocorticoid supplement. Your veterinarian decides the plan and the dose.
For concurrent disease, treatment targets that disease. Kidney support, heart medication, dental care, or a diet change may all be part of the picture.
Diet matters too. Caloric restriction is the main strategy for reducing body fat in overweight dogs, and in one study all diet groups lost a similar 4.5% of body weight under caloric restriction regardless of whether they ate commercial dry food, homemade food, or a mix [6]. That said, a dog losing weight for the wrong reason does not need calorie restriction. It needs a diagnosis. If your dog is overweight and otherwise healthy, our dog weight loss tips article covers safe feeding plans.
Recovery, Outlook, and Long-Term Management
Most dogs with well-controlled Cushing's disease live comfortably for years. The outlook changes when weight loss enters the picture, because it usually means a second problem or a treatment issue.
What long-term care looks like:
- Monthly weigh-ins at home or at the clinic, recorded in a log
- Rechecks at the interval your veterinarian sets, with bloodwork to check cortisol control
- Body condition and muscle scoring at every visit
- Prompt testing when appetite, thirst, or energy changes
- A written medication schedule so doses are never missed or doubled
Dogs on trilostane need regular monitoring because the correct dose can shift as weight and health change [3]. If your dog has lost weight, ask for a recheck sooner than the routine interval. Our guide to what to expect from diagnosis to daily management of Cushing's disease covers the day-to-day routine.
Prevention
You cannot prevent Cushing's disease itself, since it starts with a pituitary tumor [1]. What you can do is catch problems early.
- Keep your dog at a healthy weight. Overweight and obese dogs respond well to structured weight loss programs, with one study reporting mean losses of 9.43% in overweight dogs and 9.83% in obese dogs over 150 days [7].
- Feed a measured amount and skip table scraps.
- Schedule wellness exams at least yearly, and twice yearly for seniors.
- Track water intake. A sudden increase is often the first sign of trouble.
- Do not skip rechecks just because your dog seems fine.
Limitations and When to Contact a Veterinarian
No article can tell you why your individual dog is losing weight. That requires an exam, bloodwork, and often imaging. Your veterinarian sets every dose and every monitoring schedule for your pet.
Contact your veterinarian the same day if your dog:
- Loses weight for two weeks or more
- Drinks and urinates far more than usual
- Has a falling weight with a strong appetite
- Is on trilostane and starts vomiting, drooling, or acting dull
- Has diarrhea that lasts more than a day
Go to an emergency clinic now if your dog:
- Collapses or cannot stand
- Vomits repeatedly and cannot keep water down
- Refuses all food for more than 24 hours
- Has a seizure, severe weakness, or unresponsiveness
- Shows bloody diarrhea or a distended, painful belly
Routine visit if your dog is stable but the scale keeps dropping, or if you notice new muscle loss over the spine and hips.
Frequently Asked Questions
Does Cushing's disease cause weight loss in dogs?
Usually no. Cushing's disease typically causes weight gain, a potbelly, and muscle wasting, not true weight loss. If your dog with Cushing's is losing weight, your veterinarian should look for a second disease such as diabetes, kidney disease, or cancer, or check whether treatment has pushed cortisol too low.
Can trilostane cause weight loss in dogs?
It can indirectly. Trilostane doses are based on body weight, so a dog that has lost weight may now be getting too much medication. Low cortisol causes vomiting, diarrhea, poor appetite, and lethargy, which leads to further weight loss. Call your veterinarian before changing or stopping the dose.
Why is my dog with Cushing's losing weight but still eating?
A strong appetite with a falling weight is a classic pattern for diabetes mellitus, which often occurs alongside Cushing's. The body cannot use glucose properly, so it burns fat and muscle instead. Your veterinarian will want to check blood sugar and urine right away.
Is weight loss ever a good sign in a dog with Cushing's?
Only if your dog was overweight and your veterinarian intentionally started a weight loss plan. Unplanned weight loss is never a good sign. It usually means something else is going on, or that treatment needs adjusting.
How often should a dog with Cushing's be weighed?
Weigh your dog at least monthly at home or at the clinic, and bring the log to every recheck. Your veterinarian will set the recheck schedule based on your dog's treatment and stability. A steady downward trend between visits is a reason to call sooner.
Related Articles
- Cushings Disease in Dogs: Pituitary vs Adrenal Hyperadrenocorticism Guide
- Why Is My Dog Losing Weight?
- Cushing Disease Dog Behavior Problems
- Dog Cushing's Disease: What to Expect from Diagnosis to Daily Management
- Dog Weight Loss Tips
- How to Tell If Your Dog's Increased Thirst Is a Sign of Cushing's Disease
References
- Cushing Disease (Pituitary-Dependent Hyperadrenocorticism) in Animals - Endocrine System. Merck Veterinary Manual.
- Cushing Syndrome (Hyperadrenocorticism) in Animals - Endocrine System. Merck Veterinary Manual.
- Evaluation of clinical, ultrasonographic, and clinicopathological findings in dogs with pituitary-dependent hypercortisolism and poor trilostane response. Journal of veterinary internal medicine, 2026.
- Catecholamine-associated left ventricular hypertrophy in dogs with hyperadrenocorticism and myxomatous mitral valve disease: a prospective pilot study. Journal of veterinary science, 2026.
- Risk Factors for Pituitary Macrotumor in Dogs With Hypercortisolism. Journal of veterinary internal medicine, 2025.
- Effects of caloric restriction and different diet types on weight loss, metabolic profile and behavior of overweight and obese dogs. Veterinary journal (London, England : 1997), 2026.
- Metabolic and urinary profiles in normal-weight, overweight and obese dogs: clinical response to an individualised weight loss programme. Research in veterinary science, 2026.