What Cushing’s Syndrome Means
Cushing’s syndrome, also called hyperadrenocorticism, is an endocrine disease in which the body produces excessive amounts of cortisol. Cortisol is a vital stress hormone made by the adrenal glands, but in excess it produces a recognizable cluster of changes including increased thirst, increased appetite, pot-belly appearance, hair loss, and thin skin. The disease is one of the more common endocrine problems in middle-aged to older dogs.
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Cushings dogs typically come in two main forms based on the underlying cause. Pituitary-dependent Cushing’s, which accounts for the great majority of cases, results from a small benign pituitary tumor producing excess ACTH (adrenocorticotropic hormone) that drives both adrenal glands to overproduce cortisol. Adrenal-dependent Cushing’s results from a tumor on one of the adrenal glands itself producing cortisol independently.
The disease is usually managed rather than cured, but with appropriate treatment most dogs do well for years. Understanding the signs and the diagnostic process helps owners catch the disease early and respond quickly to changes during long-term management.
Recognizing the Signs
The classic signs of Cushing’s are often dismissed as ordinary aging in early stages. Increased thirst is usually the first sign owners notice; the water bowl needs refilling more often, and the dog asks to go out more frequently. Increased appetite is also common, with dogs becoming food-obsessed in ways they were not before.
The pot-belly appearance is distinctive. The abdomen sags from a combination of muscle weakness, redistribution of fat, and an enlarged liver. Hair loss is symmetrical, typically on the trunk, while the head and legs keep their fur. Skin becomes thin and bruises easily. Some dogs develop calcium deposits in the skin (calcinosis cutis), which appear as firm, white, painful lumps.
Panting that seems out of context, muscle weakness, exercise intolerance, and recurrent urinary or skin infections round out the picture. Behavior may shift, with some dogs becoming restless or anxious. The combination of signs in a senior dog should prompt evaluation for Cushing’s even if individual signs are mild.
Why It Develops
Pituitary-dependent Cushing’s is caused by a microadenoma (small benign tumor) of the pituitary gland that produces too much ACTH. This stimulates both adrenal glands to enlarge and overproduce cortisol. The pituitary tumor itself is usually small and rarely causes neurological signs, but in a minority of cases it grows large enough to compress nearby brain structures.
Adrenal-dependent Cushing’s is caused by a tumor of one adrenal gland (the other adrenal becomes small and quiet because the body’s feedback systems try to suppress cortisol). About half of these adrenal tumors are benign and half are malignant, and surgical removal can be curative for benign tumors.
Iatrogenic Cushing’s is a third form, caused by long-term administration of steroid medications. The signs are the same as natural Cushing’s, but management involves carefully tapering the steroids under veterinary direction.
The Diagnostic Workup
Diagnosis is multi-step and can take time. Your veterinarian will start with a thorough exam and routine bloodwork and urinalysis. Common findings include elevated alkaline phosphatase, dilute urine, and changes in liver values. These findings raise the suspicion of Cushing’s but do not confirm it.
Specific testing follows. The two main screening tests are the low-dose dexamethasone suppression test (LDDST) and the ACTH stimulation test. Each has strengths and limitations, and your veterinarian will choose based on the individual situation. Both involve drawing blood at specific times around the administration of a hormone or medication.
If Cushing’s is confirmed, additional testing helps distinguish pituitary from adrenal forms. Abdominal ultrasound visualizes the adrenal glands and shows whether one is enlarged with a tumor or both are symmetrically enlarged. The high-dose dexamethasone suppression test or endogenous ACTH measurement can also help differentiate.
Pituitary-Dependent Treatment
Pituitary-dependent Cushing’s, which accounts for the majority of cases, is most commonly treated with trilostane. Trilostane works by inhibiting the enzyme that produces cortisol, reducing cortisol output regardless of how much ACTH the pituitary is making. It is given once or twice daily by mouth.
Doses are individualized and adjusted based on response. Your veterinarian will start at a conservative dose and increase based on follow-up testing, typically using ACTH stimulation tests at intervals to assess control. Never adjust the dose on your own without veterinary direction; over-suppression of cortisol can produce its own serious problems.
Mitotane is an older medication that selectively destroys cortisol-producing adrenal cells. It is still used in some cases, particularly when trilostane is not tolerated or available. Mitotane has a more complex protocol with induction and maintenance phases. Your vet will explain the specifics if this is the chosen approach.
Adrenal-Dependent Treatment
Adrenal-dependent Cushing’s caused by a tumor on one adrenal gland is sometimes managed surgically. Adrenalectomy, the surgical removal of the affected gland, can be curative for benign tumors and may significantly extend life for malignant ones. The surgery is technically demanding and is typically performed by a board-certified surgeon at a specialty center.
Pre-surgical workup includes detailed imaging (often CT scan) to assess the tumor and check for invasion into nearby blood vessels or distant spread. Some dogs are not surgical candidates due to tumor invasion or general health concerns; medical management with trilostane or mitotane is then used.
Post-surgical care includes careful monitoring for adrenal insufficiency, since the remaining adrenal gland may be temporarily suppressed. Most dogs recover well from surgery and return to good quality of life.
Monitoring and Follow-Up
Long-term management requires regular rechecks. ACTH stimulation tests at appropriate intervals confirm that cortisol is in the desired range, neither too high (uncontrolled disease) nor too low (over-suppression). Bloodwork checks general health and screens for complications.
Owners are an essential part of monitoring. A simple log of water intake, appetite, energy, and any new signs is invaluable. Many veterinarians recommend keeping a “Cushing’s diary” to track changes between recheck visits. Bring it to every appointment.
Doses may need adjustment over time. As the disease progresses or responds, the trilostane dose may go up or down. Some dogs achieve excellent control on a stable dose for years; others need more frequent adjustments. Patience and consistent communication with your vet are part of long-term success.
Possible Complications
Cushing’s disease comes with several potential complications. Urinary tract infections are common because dilute urine is a poor barrier to bacteria. Diabetes can develop or worsen because excess cortisol counteracts insulin. Hypertension and proteinuria put extra strain on the kidneys. Pulmonary thromboembolism is a serious but uncommon complication.
Skin and coat problems, including thinning hair, calcinosis cutis, and recurrent skin infections, are part of the disease and may improve with treatment. Pancreatitis can occur in some dogs. Each of these complications has its own management.
Over-suppression from medication (effectively creating Addison’s disease) is a recognized complication of trilostane and mitotane therapy. Signs include weakness, vomiting, diarrhea, and collapse. This is why dose monitoring matters and why owners should call promptly with any concerning signs.
Living With Cushing’s
Day to day, dogs with Cushing’s benefit from accommodations that match their changed needs. Plenty of fresh water, more frequent potty breaks, soft bedding for tender joints, and patience with appetite changes all help. Skin care matters too, including gentle bathing and prompt attention to any new lumps or infections.
Stress management has a real role. Hormonal imbalance can amplify anxiety, so predictable routines, calm households, and gentle exercise serve your dog well. If your dog is showing behavior changes, your vet may suggest behavior support alongside the medical workup.
Many dogs respond very well to treatment, with significant improvement in appetite regulation, water intake, energy, and coat quality within weeks to months. Owners often describe their dog as “more like themselves” once cortisol is controlled.
Long-Term Outlook
The long-term outlook for treated Cushing’s dogs is generally good. Many dogs live for years with well-managed disease. The dogs that struggle most are usually those with significant concurrent conditions or whose disease is diagnosed late. Modern treatment options have substantially improved life expectancy and quality of life compared with decades past.
Plan on lifelong medication, periodic ACTH stimulation tests, and ongoing attention to concurrent conditions. The cost is a real ongoing commitment but manageable for most families with planning. Insurance coverage varies and is worth investigating early.
For broader reading on related conditions, see our guides on diabetes, which often coexists with Cushing’s, and Addison’s disease, the opposite end of the adrenal disease spectrum. The dog care blog covers many related senior wellness topics.
Adopting a Dog With Cushing’s
Dogs with diagnosed Cushing’s sometimes need rehoming when their original families cannot manage the cost or routine. With consistent care, these dogs make wonderful companions. The adopt a dog hub has guidance on what to ask shelters about medical history.
If you are considering adopting a dog with Cushing’s, ask about the type (pituitary or adrenal), current medications and doses, recent monitoring results, and recheck schedule. Be prepared for the cost of medication and periodic testing. Many adopters find that a senior dog with managed disease offers profound companionship.
Frequently Asked Questions
Is Cushing’s syndrome curable?
It depends on the cause. Adrenal tumors that are surgically removed can sometimes be cured. Pituitary-dependent disease and most other forms are managed long term rather than cured, though many dogs live well for years with appropriate treatment.
How is Cushing’s diagnosed?
Diagnosis involves clinical signs, routine bloodwork, and specific testing such as the low-dose dexamethasone suppression test or ACTH stimulation test. Imaging of the adrenal glands helps distinguish pituitary from adrenal forms. The workup is multi-step and may take weeks.
Are there side effects from Cushing’s medications?
Yes. Both trilostane and mitotane can cause over-suppression of cortisol, leading to weakness, vomiting, and other signs. Other side effects vary by medication. Regular monitoring and prompt communication with your vet help catch problems early.
Will treatment make my dog feel better?
Most dogs respond well to treatment, with improvements in thirst, appetite, energy, and coat over weeks to months. The improvement is often dramatic and validates the diagnostic and treatment effort. Some dogs require dose adjustments to find the right balance.
What if I cannot afford treatment?
Talk openly with your veterinarian about cost concerns. Less expensive options may exist, and some practices offer payment plans. Some dogs do reasonably well with conservative management of complications even when specific Cushing’s treatment is not affordable. Early conversation helps everyone make the best plan possible.
When should I call my veterinarian?
Call for any new weakness, vomiting, diarrhea, change in thirst or appetite, or signs of skin infection. Routine rechecks at intervals set by your veterinarian (typically every few months once stable) are essential for catching changes and adjusting treatment.
