Dogs with Cushing’s disease do best on a diet built around high-quality animal protein, limited fat, and slow-digesting carbohydrates. Because excess cortisol breaks down muscle, raises blood lipids, enlarges the liver, and can push blood sugar dangerously high, every ingredient choice matters. The right food won’t cure Cushing’s, but it directly supports the organs and systems that cortisol is working against.
Why Diet Matters With Cushing’s
Cushing’s disease (hyperadrenocorticism) floods your dog’s body with cortisol. That single hormone triggers a cascade of nutritional problems: muscle wasting from protein breakdown, elevated cholesterol and triglycerides, a swollen and overworked liver, persistent hunger that leads to weight gain, and blood sugar spikes that can tip into secondary diabetes. A standard maintenance dog food isn’t designed to address any of these issues. Adjusting what goes into the bowl gives your dog’s body a better chance of handling the cortisol load, whether or not medication is also part of the plan.
Prioritize High-Quality Animal Protein
Cortisol is catabolic, meaning it actively breaks down your dog’s lean muscle to convert protein into energy. Over time this causes visible muscle loss, especially along the back legs and spine. Replacing that lost protein is one of the most important things diet can do.
Animal-based proteins (chicken, turkey, beef, eggs, fish) have a more complete amino acid profile for dogs than plant-based proteins, so your dog gets more usable protein per calorie. That efficiency matters here. With plant proteins, a dog would need to eat significantly more calories just to meet its essential amino acid needs, and extra calories are the last thing a Cushing’s dog needs. Look for foods that list a named animal protein as the first ingredient, and ideally the second as well. Lean cuts are preferable since you’ll also want to keep fat in check.
Keep Fat Low
Elevated blood lipids are one of the most common complications of Cushing’s. High cortisol directly causes cholesterol and triglycerides to rise, and if those levels stay high they increase the risk of pancreatitis, a painful and potentially life-threatening inflammation of the pancreas. A low-fat diet is the primary dietary tool for bringing lipids down.
Many veterinary nutritionists suggest targeting roughly 8 to 15 percent fat on a dry-matter basis, though the exact number depends on your dog’s bloodwork and history. Commercial “low-fat” or “weight management” formulas often fall in this range. The tradeoff is palatability: animal fat is what makes food taste good to dogs, so some picky eaters resist low-fat kibble. Mixing in a small amount of warm water or low-sodium broth can help.
Table scraps and high-fat treats are especially problematic. If your dog is the type to raid the trash or beg at the table, keeping those sources of fat completely off-limits is important for the long term. Many dogs with elevated lipids will need to stay on a restricted-fat diet for life, similar to people managing high cholesterol.
Choose Slow-Digesting Carbohydrates
Dogs with Cushing’s are at heightened risk for insulin resistance and secondary diabetes, so carbohydrate quality matters more than it would in a healthy dog. The goal is to avoid sharp spikes in blood sugar after meals.
Research on glycemic response in dogs found significant differences between carbohydrate sources. Cooked white rice produced the highest blood sugar spike, with a glycemic index (GI) of 71. Traditional grain-based kibbles scored even higher at 83. By contrast, diets containing pulses like lentils and peas produced a much gentler curve: a grain-free diet made with pulses scored just 41, well within the “low GI” category. Dogs eating the pulse-based food had lower peak blood sugar, lower peak insulin, and a longer, slower rise to that peak.
In practical terms, look for foods that use lentils, peas, chickpeas, or sweet potatoes as their primary carbohydrate source rather than white rice or corn. Whole grains are a middle ground, scoring around 56 in the same study. If your dog is already on a grain-based kibble, switching to one built around pulses or whole grains can meaningfully flatten the post-meal blood sugar curve.
Use Fiber to Manage Hunger
One of the most frustrating symptoms of Cushing’s is polyphagia, a relentless, exaggerated hunger driven by cortisol. Your dog isn’t misbehaving; the hormone is literally telling its brain it’s starving. This leads to begging, counter-surfing, and overeating, all of which accelerate weight gain.
Moderate fiber helps in two ways. It adds bulk to the meal so your dog feels physically fuller, and it slows digestion so that feeling of fullness lasts longer between meals. Good fiber sources include sweet potatoes, green beans, broccoli, pumpkin, and the pulses already mentioned. Many “weight management” commercial formulas are designed with higher fiber for exactly this reason. Feeding two or three smaller meals instead of one large one can also help keep hunger more manageable throughout the day.
Support the Liver
Cushing’s almost always enlarges the liver. Cortisol forces the liver to store excess glycogen and work harder at detoxification, which depletes its natural antioxidant defenses. Most dogs and cats with liver problems are deficient in glutathione, the liver’s main protective antioxidant.
A supplement called SAMe (S-adenosylmethionine) helps restore glutathione levels. It works in two steps: first it supports the structural integrity of liver cell membranes, then it converts into glutathione itself, which protects liver cells from the toxic byproducts they process daily. Veterinary products like Denosyl and Denamarin are the most common forms. These come in a range of tablet sizes matched to your dog’s weight. SAMe is best given on an empty stomach for proper absorption. Your vet can recommend the right dose based on your dog’s size and liver values.
Supplements That May Lower Cortisol
Two over-the-counter supplements have shown enough promise that veterinary endocrinologists use them as part of Cushing’s management, particularly for milder cases or dogs with hair loss.
Melatonin inhibits enzymes involved in cortisol production. The University of Tennessee’s veterinary endocrinology program suggests 3 mg twice daily for dogs under 30 pounds and 6 mg twice daily for dogs over 30 pounds. It’s inexpensive and has few side effects, which is why it’s often tried first. Results take time: allow at least four months before judging whether it’s working.
Flaxseed lignans (specifically SDG lignans from flax hulls) also inhibit some of the same cortisol-producing enzymes. A commonly suggested dose is one milligram per pound of body weight per day. Melatonin and lignans are frequently used together because they complement each other’s mechanisms, both working to lower cortisol and other adrenal hormones like estradiol and androstenedione. Neither replaces prescription Cushing’s medication for moderate or severe cases, but they can be a useful addition to the overall plan.
Putting It All Together
A Cushing’s-friendly bowl looks like this: a named animal protein as the foundation, fat kept to the lower end of the range (around 8 to 15 percent dry matter), slow-digesting carbohydrates from lentils, peas, or sweet potatoes, and enough fiber to take the edge off constant hunger. Lean meats, eggs, and high-fiber vegetables like green beans make good toppers or treats in place of commercial biscuits.
Homemade diets are tempting because they give you full control over ingredients, but they carry real risk. Unbalanced homemade meals commonly fall short on essential micronutrients, and nutrient deficiencies can create new health problems on top of the ones you’re trying to manage. If you want to cook for your dog, have the recipe formulated by a board-certified veterinary nutritionist to make sure it’s complete.
Finally, weigh your dog regularly. Cushing’s dogs tend to gain fat while losing muscle, so their weight can stay stable even as their body composition worsens. Feeling for the ribs and watching the waistline from above are better indicators than the scale alone. Adjusting portions based on body condition rather than a fixed cup measurement keeps your dog closer to a healthy lean weight as the disease is managed over time.