Cushing's Disease in Dogs: Symptoms, Treatment & Diet Guide

Cushing's disease in dogs, also known as hyperadrenocorticism, is one of the most commonly diagnosed endocrine disorders in middle-aged and older dogs. It develops when the adrenal glands produce too much cortisol, the body's primary stress hormone, leading to a constellation of changes that pet parents often mistake for normal aging: increased thirst, a swollen belly, thinning hair, and constant hunger. This guide covers what causes Cushing's disease, how it is diagnosed and treated, and what the current veterinary evidence says about nutrition, including how plant-based diets relate to the dietary principles veterinarians use to manage the condition.

What Is Cushing's Disease in Dogs?

Cushing's disease, formally called hyperadrenocorticism (HAC), is a syndrome that results from chronic exposure to excessive concentrations of cortisol. Cortisol is produced by the two adrenal glands, which sit just in front of the kidneys, and its production is normally regulated by adrenocorticotropic hormone (ACTH) released by the pituitary gland at the base of the brain. When this feedback loop is disrupted, cortisol stays elevated, and the body slowly responds with the recognizable changes that define the disease.

According to the Merck Veterinary Manual, there are three principal forms of the disease.

Pituitary-Dependent Hyperadrenocorticism (PDH)

A small, usually benign tumor of the pituitary gland (an adenoma) secretes excess ACTH, which in turn drives both adrenal glands to overproduce cortisol. PDH accounts for roughly 80 to 85 percent of naturally occurring cases.

Adrenal-Dependent Hyperadrenocorticism (ADH)

A tumor of one or both adrenal glands produces cortisol independently of pituitary signals. ADH accounts for the remaining 10 to 15 percent of spontaneous cases. According to Cornell University's Riney Canine Health Center, roughly half of these adrenal tumors are benign adenomas and half are malignant carcinomas.

Iatrogenic Cushing's Disease

This form is caused by long-term administration of corticosteroid medications such as prednisone. It typically resolves once the steroid is gradually tapered under veterinary supervision.

Signs and Symptoms of Cushing's Disease

The onset of Cushing's disease is insidious. Many pet parents describe a slow drift of small changes that they initially attribute to aging. The most common clinical signs, as summarized by Cornell University College of Veterinary Medicine, are listed below.

Category	Common Signs
Behavior	Increased thirst and urination (in 80 to 90 percent of cases), increased appetite, excessive panting, lethargy
Appearance	Pot-bellied or sagging abdomen, symmetrical hair loss, thinning skin, calcinosis cutis (skin mineralization), poor wound healing
Muscle and energy	Muscle wasting, weakness, exercise intolerance
Associated conditions	Recurrent urinary tract and skin infections, diabetes mellitus, gallbladder mucocele, hypertension, blood clots

A 2020 study in the Journal of Veterinary Internal Medicine reported that systemic hypertension was present in 82 percent of dogs with naturally occurring Cushing's disease, with nearly half of those dogs showing severe hypertension (systolic blood pressure of 180 mm Hg or higher). This is why veterinarians routinely measure blood pressure in dogs with suspected or confirmed Cushing's.

Causes and Which Dogs Are at Risk

Cushing's disease is primarily a disease of middle-aged and older dogs, with most diagnoses occurring between ages seven and twelve. A 2022 UK primary-care study of more than 900,000 dogs estimated a one-year period prevalence of 0.17 percent, with the highest risk seen in Bichon Frises, Border Terriers, and Miniature Schnauzers. Cornell's clinical summary adds Boston Terriers, Dachshunds, Jack Russell Terriers, Lhasa Apsos, Miniature Poodles, Staffordshire Terriers, and Yorkshire Terriers to the list of predisposed breeds.

By contrast, the same UK study found that Golden Retrievers and Labrador Retrievers had significantly lower odds of being diagnosed with Cushing's compared to the general dog population. Adrenal-dependent disease is more often seen in larger breeds, including German Shepherds.

Increasing age and a bodyweight greater than the breed-sex average were both independently associated with higher risk. The underlying cause of pituitary tumors in dogs is not well understood, and there is no established way to prevent the disease.

How Cushing's Disease Is Diagnosed

No single test definitively diagnoses Cushing's disease. Veterinarians combine clinical signs, baseline blood work, and one or more specialized hormonal tests. The most consistent biochemical finding is a substantial increase in alkaline phosphatase (ALP) activity, often accompanied by elevated cholesterol and triglycerides, dilute urine, and mildly elevated phosphorus, as outlined in Today's Veterinary Practice.

Screening Tests

The two most common screening tests are the low-dose dexamethasone suppression test (LDDST) and the ACTH stimulation test. The LDDST is generally considered the preferred initial screening test in most cases because of its higher sensitivity, though it takes about eight hours to complete. The ACTH stimulation test is shorter and is the test of choice when iatrogenic Cushing's is suspected. The urine cortisol-to-creatinine ratio (UCCR) is highly sensitive but not specific, and is typically used to help rule the disease out rather than confirm it.

Differentiating Pituitary from Adrenal Disease

Once Cushing's is confirmed, distinguishing pituitary-dependent from adrenal-dependent disease matters because treatment differs. Abdominal ultrasound assesses the size and symmetry of the adrenal glands, and a high-dose dexamethasone suppression test or endogenous ACTH measurement can help clarify the source. Blood pressure measurement and urine culture are typically added because both hypertension and silent urinary tract infections are common.

Treatment Options

Cushing's disease is generally managed rather than cured. Treatment is typically started when clinical signs begin to affect a dog's quality of life or when complications such as severe hypertension, recurrent infections, or insulin resistance are present.

Trilostane (Vetoryl)

Trilostane is the only FDA-approved oral medication for both pituitary-dependent and adrenal-dependent Cushing's in dogs. It works by reversibly inhibiting an enzyme (3β-hydroxysteroid dehydrogenase) required for cortisol synthesis, lowering circulating cortisol within hours. Dogs on trilostane require periodic monitoring, typically every three months for life, to ensure cortisol is suppressed appropriately without overshooting into iatrogenic Addisonian crisis. A 2022 study in Veterinary Record of 91 dogs treated with low-dose twice-daily trilostane reported a median survival time of 998 days (roughly 2.7 years).

Mitotane (Lysodren)

Mitotane is an older off-label medication that selectively destroys cortisol-producing adrenal cells. It is used less frequently today than trilostane, primarily because it requires careful induction protocols and carries a higher risk of permanent adrenal damage. It remains a reasonable option for some dogs, particularly those that do not respond well to trilostane.

Surgery and Radiation

For adrenal-dependent disease, surgical removal of the affected adrenal gland (adrenalectomy) is the preferred treatment when the dog is a good surgical candidate. Cornell notes that surgery carries a 10 to 25 percent mortality risk but can be curative when the tumor is small and benign. For pituitary-dependent disease, hypophysectomy (surgical removal of the pituitary tumor) and stereotactic radiation are both available at select referral hospitals, with reported average survival times of two to five years.

Diet and Nutrition for Dogs with Cushing's Disease

There is no single prescription diet that all veterinary nutritionists agree is best for Cushing's disease. Diet does not lower cortisol or replace medication. What well-formulated nutrition can do is help manage the complications that frequently accompany the disease, including hyperlipidemia, hypertension, muscle loss, and predisposition to pancreatitis. The dietary principles most commonly endorsed in veterinary literature are summarized below.

Moderate to Lower Fat

Cortisol elevation drives increases in serum triglycerides and cholesterol. Most cushingoid dogs have hyperlipidemia at diagnosis, and persistent hyperlipidemia is associated with increased risk of pancreatitis and other complications. Veterinary nutrition references commonly recommend a lower-fat diet paired with increased dietary fiber for dogs with diet-responsive hyperlipidemia.

High-Quality, Highly Digestible Protein

Sustained cortisol exposure causes muscle catabolism and contributes to the abdominal muscle weakness that produces the classic pot-bellied appearance. Adequate dietary protein, sourced from digestible ingredients, helps preserve lean mass. Unless a dog has concurrent kidney disease that requires protein restriction, moderate to higher protein intake is typically supported by current evidence on senior dog nutrition. For a deeper discussion, see our science-based guide to protein requirements in senior dogs.

Controlled Sodium

Because systemic hypertension is so common in Cushing's, reducing dietary sodium is a sensible adjunct to medical therapy. Veterinary nutrition guidance from the Purina Institute and others advises avoiding high-sodium treats, table scraps, and processed foods.

Omega-3 Fatty Acids

Long-chain omega-3 fatty acids (EPA and DHA) have been shown in controlled canine studies to reduce serum triglycerides and total cholesterol. A 2021 study in Schnauzers with primary hyperlipidemia found that omega-3 supplementation paired with a low-fat diet reduced mean triglycerides from 391 mg/dL to 119 mg/dL over 90 days. Marine microalgae provides EPA and DHA in a plant-based form, with the same fatty-acid molecules fish derive from algae in the marine food chain.

Antioxidants and Polyphenols

Antioxidants such as vitamin E, vitamin C, and plant-derived polyphenols like curcumin (from turmeric) are commonly included in formulations intended for older dogs with chronic inflammatory conditions. The strength of clinical evidence varies by compound, and antioxidants are best regarded as a complement to, not a replacement for, medical therapy. Always speak with your veterinarian before adding supplements, particularly for a dog on medication.

Consistent Portions and Hydration

Polyphagia (excessive hunger) is one of the hallmark signs of Cushing's, and weight gain can compound metabolic stress. Consistent measured portions, a steady feeding schedule, and continuous access to fresh water are simple but important. Always work with your veterinarian when planning a diet change, especially if your dog is also being treated for diabetes mellitus or kidney disease, where additional nutritional adjustments may be needed.

The Role of Plant-Based Diets

There are currently no peer-reviewed studies that specifically evaluate plant-based diets in dogs with Cushing's disease. What does exist is a growing body of research showing that nutritionally complete plant-based diets can maintain clinical health markers in adult dogs, and a parallel body of evidence on the dietary principles that benefit dogs with Cushing's-related complications. The honest framing is this: plant-based diets are not a treatment for Cushing's, but a well-formulated plant-based diet can align closely with the nutritional priorities veterinarians already recommend for dogs with the disease.

What the Evidence on Plant-Based Diets Shows

A 12-month prospective cohort study published in PLOS ONE followed 15 adult dogs transitioned from meat-based to a complete plant-based diet and found that clinical, hematological, and nutritional parameters were maintained within normal limits. A larger 2022 survey study of 2,536 dogs reported that those fed nutritionally complete plant-based diets had equivalent or better guardian-reported health outcomes compared with conventional meat-based diets, after controlling for canine demographic factors. These findings do not establish that plant-based diets prevent or treat any disease. They do support the conclusion that, when formulated by a qualified veterinary nutritionist and meeting AAFCO nutrient profiles, plant-based diets can be nutritionally adequate for healthy adult dogs.

Where Plant-Based Formulations Align with Cushing's Dietary Goals

Well-designed plant-based recipes for dogs tend to share several structural features that overlap with the recommendations above: moderate fat content, plant-derived omega-3 from sources such as flaxseed and marine microalgae, fiber from whole foods like pumpkin and oats, and inclusion of polyphenol-rich ingredients such as turmeric. Phosphorus in plant proteins is also stored largely as phytate, a form that dogs absorb less efficiently than the phosphorus in animal proteins, which can be relevant when concurrent kidney disease is present. None of these properties is unique to plant-based diets, and meat-based diets can be formulated to similar specifications.

A Note on Petaluma's Senior Formula

Petaluma's Baked Pumpkin and Peanut Butter Flavor for Senior Dogs was formulated by Dr. Blake Hawley DVM with several aging-related considerations in mind: 9.5 percent fat, reduced sodium and phosphorus compared to the adult recipe, 450 mg DHA per cup from marine microalgae, and the inclusion of curcumin (from turmeric extract paired with black pepper) and glucosamine. These attributes happen to overlap with much of the dietary guidance for Cushing's, though the formula is designed for healthy senior dogs and is not a therapeutic diet. Any dietary change for a dog with Cushing's should be discussed with your veterinarian, particularly when other conditions such as diabetes mellitus, pancreatitis, or chronic kidney disease are present.

Prognosis and Long-Term Care

With accurate diagnosis and appropriate treatment, Cushing's disease can be very well managed. Behavioral signs such as excessive drinking and panting often improve within a few weeks of starting trilostane. Skin and coat changes can take several months to resolve. Cornell summarizes the prognosis as follows: dogs with pituitary-dependent disease treated medically have an average survival of two to two-and-a-half years, while those treated with surgery or radiation can average two to five years. For adrenal-dependent disease, successful adrenalectomy yields an average survival of 1.5 to four years, while medical management averages about one year.

Long-term care typically involves periodic monitoring of cortisol, blood pressure, urine, and body condition. Because many cushingoid dogs are also seniors, broader supportive care matters: joint maintenance, cognitive enrichment, and weight management. For a wider look at supporting senior wellness, see our guide to optimal nutrition for aging dogs.

Frequently Asked Questions

What is the life expectancy of a dog with Cushing's disease?

With medical treatment, dogs with pituitary-dependent Cushing's live an average of two to two-and-a-half years, and a recent study of dogs on low-dose twice-daily trilostane reported a median survival of about 2.7 years. Surgical or radiation therapy can extend that to two to five years. Outcomes depend on age at diagnosis, the type of Cushing's, and how well comorbidities like hypertension and diabetes are managed.

What foods should a dog with Cushing's disease avoid?

Veterinary nutritionists generally advise avoiding high-fat foods, salty treats, processed table scraps, and rich human foods. Persistent hyperlipidemia in cushingoid dogs is linked to a higher risk of pancreatitis, so low-fat, low-sodium options are typically preferred. Treats should be portion-controlled to prevent weight gain, given that polyphagia is a hallmark sign.

Can diet alone treat Cushing's disease in dogs?

No. Diet does not lower cortisol or shrink pituitary or adrenal tumors. Diet supports the management of secondary complications such as hyperlipidemia, hypertension, and muscle loss, and it works alongside medical therapy such as trilostane or mitotane.

Is a plant-based diet safe for a dog with Cushing's disease?

There are no Cushing's-specific studies on plant-based diets in dogs. Available research shows that nutritionally complete plant-based diets can maintain clinical health in adult dogs, and many of the characteristics of well-formulated plant-based diets, such as moderate fat, plant-based omega-3, and lower phosphorus bioavailability, align with general dietary recommendations for Cushing's. Any major diet change should be discussed with your veterinarian, especially if your dog has comorbidities or is on medication.

What is the most common treatment for Cushing's disease in dogs?

Trilostane (Vetoryl) is the most common treatment and is the only FDA-approved medication for both pituitary-dependent and adrenal-dependent Cushing's. It is typically given once or twice daily, with cortisol levels and clinical signs monitored regularly to fine-tune dosing.

Can Cushing's disease be prevented?

There is no known way to prevent naturally occurring (pituitary or adrenal) Cushing's disease. Iatrogenic Cushing's, caused by long-term corticosteroid medications, can be minimized by using the lowest effective steroid dose for the shortest necessary duration, under veterinary supervision.

Which dog breeds are most at risk for Cushing's disease?

Breeds with consistently elevated risk include the Bichon Frise, Border Terrier, Miniature Schnauzer, Dachshund, Miniature Poodle, Yorkshire Terrier, Boston Terrier, and Staffordshire Terrier. Larger breeds such as German Shepherds are over-represented among adrenal-dependent cases. Golden Retrievers and Labrador Retrievers appear to have a lower-than-average risk.

References

1. Cornell University College of Veterinary Medicine, Riney Canine Health Center. Cushing's syndrome. vet.cornell.edu
2. Merck Veterinary Manual. Cushing Syndrome (Hyperadrenocorticism) in Animals. merckvetmanual.com
3. Schofield I, Brodbelt DC, Niessen SJM, Church DB, Geddes RF, O'Neill DG. Frequency and risk factors for naturally occurring Cushing's syndrome in dogs attending UK primary-care practices. J Small Anim Pract. 2022;63(4):265-274. PMC9299886
4. García San José P, Arenas Bermejo C, Clares Moral I, Cuesta-Alvaro P, Pérez Alenza MD. Prevalence and risk factors associated with systemic hypertension in dogs with spontaneous hyperadrenocorticism. J Vet Intern Med. 2020;34(5):1768-1778. PMC7517838
5. García San José P, Arenas Bermejo C, Alonso-Miguel D, Clares Moral I, Cuesta-Alvaro P, Pérez Alenza MD. Survival of dogs with pituitary-dependent hyperadrenocorticism treated twice daily with low doses of trilostane. Vet Rec. 2022;191(1):e1630. PMID 35460587
6. Carotenuto G, Malerba E, Dolfini C, et al. Cushing's syndrome — an epidemiological study based on a canine population of 21,281 dogs. Open Vet J. 2019;9(1):27-32. PMC6500859
7. Cook A. The Diagnosis of Canine Hyperadrenocorticism. Today's Veterinary Practice. 2022. todaysveterinarypractice.com
8. Linde A, Lahiff M, Krantz A, Sharp N, Ng TT, Melgarejo T. Domestic dogs maintain clinical, nutritional, and hematological health outcomes when fed a commercial plant-based diet for a year. PLoS ONE. 2024;19(4):e0298942. PMC11020905
9. Knight A, Huang E, Rai N, Brown H. Vegan versus meat-based dog food: Guardian-reported indicators of health. PLoS ONE. 2022;17(4):e0265662. PMID 35417464
10. de Albuquerque P, De Marco V, Vendramini THA, Amaral AR, Catanozi S, Santana KG, Nunes VS, Nakandakare ER, Brunetto MA. Supplementation of omega-3 and dietary factors can influence the cholesterolemia and triglyceridemia in hyperlipidemic Schnauzer dogs: A preliminary report. PLoS ONE. 2021;16(10):e0258058. PMID 34665804
11. Purina Institute. Hyperlipidemia in Dogs. purinainstitute.com
12. VCA Animal Hospitals. Cushing's Disease in Dogs. vcahospitals.com

This article is intended for educational purposes and is not a substitute for veterinary advice. If you suspect your dog has Cushing's disease or is experiencing any new symptoms, please consult your veterinarian. Diet changes for dogs with chronic conditions should always be discussed with your veterinary team.