Treating Cushing’s disease in dogs usually means daily medication to control excess cortisol production, and most dogs respond well enough to enjoy a good quality of life for years. The right treatment depends on whether the disease originates in the pituitary gland or in an adrenal tumor, so a clear diagnosis is the essential first step before any therapy begins.
About 85% of dogs with Cushing’s have the pituitary-dependent form, where a small tumor on the pituitary gland signals the adrenal glands to overproduce cortisol. The remaining 15% have an adrenal tumor directly pumping out excess cortisol. Both forms produce the same familiar symptoms (increased thirst, frequent urination, pot belly, hair loss, panting), but the treatment paths diverge significantly.
Trilostane: The Most Common Medication
Trilostane is the go-to drug for most dogs with Cushing’s. It works by blocking an enzyme the adrenal glands need to manufacture cortisol, effectively turning down the volume on cortisol production without destroying the glands themselves. It’s a daily, lifelong medication given with food.
The FDA-approved dose ranges from 2.2 to 6.7 mg per kilogram of body weight per day, but many veterinarians start lower, around 1 mg/kg twice daily. Starting low and adjusting upward reduces the risk of dropping cortisol too far, too fast. Although the label says once daily, multiple studies have found twice-daily dosing works better for many dogs because trilostane’s effects wear off before the full 24 hours are up. Your vet will choose a starting dose based on your dog’s weight and the available capsule sizes, then fine-tune from there.
Most owners notice improvements within the first few weeks. Water intake drops back toward normal, energy levels pick up, and the relentless hunger eases. Coat regrowth takes longer, often several months, because hair follicles need time to recover from prolonged cortisol exposure.
Monitoring After Starting Treatment
Trilostane requires careful follow-up, especially early on. Rechecks are typically scheduled at 10 to 14 days and again at 30 days after starting the medication or changing the dose. Once your dog is stable, monitoring shifts to every 90 days. These visits usually include bloodwork and a cortisol stimulation test performed 3 to 5 hours after the morning dose.
Your vet is looking at two things: lab results and how your dog is actually doing at home. Interestingly, cortisol test results don’t always line up perfectly with clinical signs, so your observations matter. Keeping a simple log of water intake, appetite, energy, and urination frequency gives your vet genuinely useful information for dose adjustments.
Signs of Over-Suppression
The biggest risk with any cortisol-lowering treatment is pushing levels too low, essentially creating the opposite problem: Addison’s disease (cortisol deficiency). Mild over-suppression causes lethargy, decreased appetite, vomiting, or diarrhea. In severe cases, a dog can develop what’s called an Addisonian crisis, with collapse, severe vomiting or bloody diarrhea, dangerously slow heart rate, and low blood sugar.
If your dog becomes lethargic, stops eating, or vomits after starting trilostane, stop the medication and contact your vet the same day. Caught early, over-suppression is reversible. Most dogs recover once the dose is reduced or temporarily paused, though a crisis requires emergency treatment with IV fluids and supplemental hormones. This is why the early monitoring schedule matters so much.
Mitotane: An Older Alternative
Before trilostane became widely available, mitotane was the standard treatment. Unlike trilostane, which simply blocks cortisol production, mitotane actually destroys portions of the adrenal gland tissue. It’s used less often now because it requires more intensive monitoring and carries a higher risk of serious side effects, but it remains an option when trilostane isn’t effective or isn’t tolerated.
Treatment starts with a “loading phase” of higher daily doses, during which the vet monitors bloodwork frequently to determine when enough adrenal tissue has been affected. The dog then transitions to a lower maintenance dose spread across the week. Some dogs need the more aggressive version of this protocol, which intentionally destroys enough adrenal tissue to permanently eliminate cortisol production. Those dogs will need cortisol and mineral-balancing hormone supplements for the rest of their lives, essentially trading Cushing’s for managed Addison’s disease.
Surgery for Adrenal Tumors
When Cushing’s is caused by an adrenal tumor (the 15% of cases), surgical removal of the affected adrenal gland is the preferred treatment whenever the tumor hasn’t spread and the dog is a reasonable surgical candidate. Adrenalectomy can be curative, eliminating the source of excess cortisol entirely.
It is, however, a high-stakes procedure. The adrenal glands sit near major blood vessels, and surgery carries a 10 to 25% risk of death, primarily from hemorrhage. Dogs that come through the operation successfully need close monitoring in the days afterward. The remaining healthy adrenal gland, which has been suppressed by the overactive one, needs time to “wake up” and resume normal function. During that recovery window, your dog will need temporary hormone supplementation.
For dogs with adrenal tumors who aren’t good surgical candidates (due to age, tumor invasion into blood vessels, or other health problems), trilostane can manage symptoms medically instead.
Radiation for Pituitary Tumors
Radiation therapy targets pituitary tumors directly and is most often recommended when the tumor is large enough to press on the brain, causing neurological symptoms like disorientation, circling, or behavior changes. Treatment sessions run two to three times per week for four to six weeks.
About 70% of dogs show good improvement after radiation, with roughly half improving quickly and the other half getting better over the following one to two months. The catch: at least half of dogs still need ongoing medication for Cushing’s even after radiation, and tumors can regrow anywhere from 2.5 to 26 months later. Side effects include loss of skin and hair pigment in the treated area, hearing loss, and sometimes reduced tear production in the eyes. Radiation is available only at specialty veterinary centers, which limits access and adds to the cost.
Diet and Lifestyle Adjustments
Dietary changes won’t treat Cushing’s on their own, but the right food supports your dog’s overall health while medication does the heavy lifting. Dogs with Cushing’s tend to carry excess body fat and are prone to high blood pressure, pancreatitis, and urinary tract infections, all of which diet can influence.
Look for a food formulated for adult maintenance (not “all life stages,” which is often higher in calories and minerals). A lower-fat formula, under 12% fat on a dry matter basis, with moderate fiber (8 to 17%) helps manage weight. Protein should come from highly digestible sources like chicken, beef, lamb, egg whites, or organ meats. If your dog has high blood pressure, your vet will likely recommend a low-sodium diet as well. Fresh water should always be freely available, since restricting water in a dog that’s drinking excessively can lead to dangerous dehydration.
What to Expect Long Term
Cushing’s is a managed condition, not a cured one (unless surgery removes the source entirely). With consistent treatment, dogs with pituitary-dependent Cushing’s have an average survival time of 2 to 5 years after diagnosis. Dogs with adrenal-dependent Cushing’s treated surgically average 1.5 to 4 years. Many dogs live at the longer end of these ranges, especially when treatment starts before serious complications like diabetes or blood clots develop.
The decision to begin treatment is typically based on quality of life. If your dog’s symptoms are mild and not progressing, your vet may recommend monitoring rather than immediate medication. Once symptoms like excessive drinking, accidents in the house, or muscle wasting start affecting daily life, that’s usually the signal to begin therapy. Treatment won’t reverse every change (some skin calcification or muscle loss may be permanent), but most dogs become noticeably more comfortable within weeks of starting medication.