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Your 9-year-old dog has been drinking a lot lately and eats everything in sight. Additionally, he has lost his hair, giving him a pot-bellied appearance. A veterinarian examination and several diagnostic tests confirmed that he had hyperadrenocorticism, commonly known as Cushing’s disease or Cushing’s syndrome. Cushing’s disease occurs when the body produces too much of a hormone called cortisol. Cortisol is produced and stored by the adrenal glands, two small glands located on top of the kidneys.
“Cortisol is one of the body’s natural steroids,” says Dr. Anne Stallman, a veterinarian at the FDA’s Center for Veterinary Medicine, adding that normal amounts of cortisol help the body adapt during times of stress. Cortisol also helps fight infections and maintain proper weight and condition.
However, excess cortisol weakens the immune system and makes the body more susceptible to other illnesses and infections.
two common types
In dogs, Cushing’s disease occurs naturally and can be either pituitary-dependent or adrenal-dependent. Approximately 80% to 85% of Cushing’s disease is pituitary dependent. That is, it is caused by a tumor in the pituitary gland, a pea-sized gland at the base of the brain.
The pituitary gland produces many hormones, including adrenocorticotropic hormone (ACTH). Pituitary tumors cause overproduction of ACTH, which travels through the bloodstream to the adrenal glands and stimulates them to produce more cortisol than the body needs.
In the remaining 15% to 20% of Cushing’s dogs, tumors in one or both adrenal glands produce excess cortisol.
The type of Cushing’s disease may determine what treatment is prescribed.
Veterinarians use blood tests to diagnose Cushing’s disease and distinguish between diseases caused by the pituitary or adrenal glands. Ultrasound may also be used to detect tumors in the adrenal glands.
Signs of Cushing’s disease
Cushing’s disease usually occurs in middle-aged to older dogs. The disease progresses slowly and early signs may not be noticed. Symptoms in dogs include:
- increased thirst
- Increased urination
- increased appetite
- decreased activity
- excessive panting
- thin or weak skin
- hair removal
- Recurrent skin infections
- Enlargement of the abdomen, resulting in a “pot-bellied” appearance
Cushing’s disease treatment
Most veterinarians treat both adrenal-dependent and pituitary-dependent Cushing’s disease with medications. The only way to “cure” Cushing’s disease is to remove the adrenal tumor, if the disease is adrenal-dependent and the tumor has not spread. However, due to the complexity and risks of surgery, most cases are treated with drug therapy. Surgical techniques to remove pituitary tumors in dogs are being investigated, but surgery is not a widely available option.
Cushing’s disease is usually a lifelong condition, but the disease can usually be managed with medication. “It’s important that your veterinarian examines your dog regularly and performs blood tests,” says Stallman. “Blood tests and monitoring response to treatment can help determine the appropriate dose, which may need to be adjusted periodically.”
Depending on your dog’s response to treatment and tolerance to the medication, frequent blood tests and veterinary visits are usually required during the first few months of treatment and then every few months thereafter. .
Vetryl (trilostane) is the only drug approved by the FDA to treat both pituitary-dependent and adrenal-dependent Cushing’s disease in dogs. This prescription drug works by stopping the production of cortisol in the adrenal glands. Vetryl should not be given to dogs that:
- have kidney or liver disease
- are taking certain drugs used to treat heart disease
- I am pregnant
The most common side effects of this drug are loss of appetite or appetite, vomiting, lack of energy, diarrhea, and weakness. In some cases, more severe side effects can occur, including bloody diarrhea, weakness, severe sodium/potassium imbalance, destruction of the adrenal glands, and even death.
Only one other drug, Anipril (selegiline), is FDA-approved to treat Cushing’s disease in dogs, but only to treat certain cases caused by pituitary tumors.
Until now, veterinarians have often used a chemotherapy drug approved for humans called Lysodren (mitotane) “off-label” to treat Cushing’s disease in dogs. Lysodren destroys the layers of the adrenal glands that produce cortisol. Careful monitoring is required and serious side effects may occur.
“Off-label” use of a drug means using an FDA-approved veterinary or human drug in a way that is not listed on the label, and is sometimes referred to as an “off-label” use. But dogs can have unexpected reactions to human drugs, so it’s helpful to have treatments that have been studied in dogs and approved specifically for dogs, Stallman said.
“Treatment of Cushing’s disease is a balancing act,” says Stallman. “However, dogs with this disease can lead good lives if they are closely monitored by a veterinarian, owners diligently take their dogs for blood tests and tests, watch for side effects, and administer medications as directed. I can.”
If you think your dog is having side effects from Vetryl, Anipryl, or any other medication, contact your veterinarian immediately. FDA recommends working with your veterinarian to report problems with your medicine. For information on how to report side effects, see How to Report Side Effects and Product Problems with Veterinary Drugs and Devices.
