Cushing’s Syndrome in Dogs

Cushing's syndrome happens when your dog’s body makes too much of a hormone called cortisol. This chemical helps him respond to stress, control his weight, fight infections, and keep his blood sugar levels in check. But too much or too little of it can cause problems.

Cushing’s, which is also known as hypercortisolism and hyperadrenocorticism, can be tricky for a vet to diagnose, because it has the same symptoms as other conditions. The key is to let your vet know about anything that’s different about your pet.

In some cases, surgery can cure dogs of the problem. If your pup can’t have an operation, he can take medicine to control his cortisol levels.

Symptoms

The condition mostly affects middle-aged and older dogs, and the warning signs may be harder to spot in the beginning.

You might notice your dog:

  • Is thirstier than usual
  • Seems hungrier
  • Pees more often. Housebroken dogs may have indoor accidents.
  • Loses hair or it seems slow to grow
  • Gets a pot belly
  • Has thinning skin
  • Seems very tired and inactive
  • Pants a lot
  • Gets skin infections

 

Types of Cushing's Syndrome

Many animals can get this condition. People can get it too.

There are two major types that affect dogs:

  • Pituitary dependent. This form is the most common, affecting about 80% to 90% of the animals who have Cushing's. It happens when there’s a tumor in a pea-sized gland at the base of the brain, called the pituitary.
  • Adrenal dependent: This type comes from a tumor in one of the glands that sit on top of the kidneys, called adrenal glands. About 15% to 20% of diagnosed dogs will have this type.

Another kind, called iatrogenic Cushing's syndrome, happens after a dog has taken steroids for a long time.

Getting Your Dog Diagnosed

There’s no method that’s 100% accurate for diagnosing Cushing's. So the vet will do a few tests to see what may be causing your pet's symptoms and to rule out other health problems.

Your vet will start by testing your dog’s blood and his pee. These exams can detect diluted urine, urinary tract infections, or problems with a protein mostly found in the liver and bones called alkaline phosphatase. All of these are common in animals with Cushing’s. If the results show signs of the condition, your vet will follow up with hormone screening tests, such as:

  • ACTH stimulation test. It measures how well the adrenal glands work in response to a hormone called ACTH that usually prompts them to make cortisol. The vet will take blood samples before and after your dog gets a shot of ACTH to see how the hormone affected him.  
  • Low dose dexamethasone suppression (LDDS) test looks at how your dog’s body works with a man-made version of cortisol, called dexamethasone. Blood samples before and after he gets a shot of the hormone help the vet see what’s going on.

If it seems like your pup could have Cushing’s, your vet might want to do an ultrasound scan of his belly. This imaging test will help her see if there’s a tumor on the adrenal glands. That could affect the kind of treatment he needs.

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Treatments

If Cushing’s syndrome comes from a tumor on your pet’s adrenal glands, the vet might be able to remove it with surgery, which will cure him of the problem. But if the tumor has spread to other parts of his body or he has other health problems, surgery may not be an option.

Usually, a dog can live an active, normal life with medication to treat the condition, though he’ll need it for the rest of his life. Drugs are best for dogs with Cushing’s syndrome caused by the pituitary gland or for those with a tumor on their adrenal gland that can't be removed with surgery.

The most common drug is trilostane (Vetoryl). Mitotane (Lysodren) is an older drug that vets don’t prescribe much anymore. It causes many side effects, but it may cost less. Your pup will need regular check-ups and blood tests to make sure his treatment is working.

If your pet has iatrogenic Cushing's syndrome, your vet can try to gradually stop giving him steroids. But the original condition they were treating will probably come back.

The most important thing you can do is to follow your dog's treatment plan. Keep a close watch on his behavior and symptoms, and give him the right medication doses at the right times. You and your vet can work together to help him live a happy, healthy life.

WebMD Medical Reference Reviewed by Amy Flowers, DVM on June 22, 2015

Sources

SOURCES:

American College Veterinary Internal Medicine. "ACVIM Fact Sheet: Cushing's Syndrome in Dogs."

The Merck Veterinary Manual. "Hyperadrenocorticism."

VCA Animal Hospitals.

University of Rochester Medical College.

FDA.

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