Hyperadrenocorticism, also know as Cushing’s disease, is a disease that can be very tricky to diagnose at first since it mainly occurs in older dogs and can be mistaken for the dog simply becoming older and going through a premature aging process. However, Cushing’s disease is very treatable and can add years to your dog’s life if it is caught early.
Cushing’s disease is one of the most common endocrine disorders in dogs. It occurs when a dog’s pituitary gland is producing too much of the cortisone hormone, which is responsible for the metabolism of protein and carbohydrates.
Cushing’s disease can occur for different reasons. Tumors are the most common cause, with three different types: Pituitary dependent hyperadrenocorticism, adrenal-based hyperadrenocorticism, and iatrogenic hyperadrenocorticism.
Pituitary dependent hyperadrenocorticism: The most common cause of Cushing’s disease occurs due to benign pituitary tumors. The tumor causes the pituitary gland to over secrete adrenocorticotrophic hormone (ACTH), leading the pituitary gland to ignore the adrenals’ response when it secretes more cortisol in return.
Adrenal-based hyperadrenocorticism: Tumors may also form in the adrenals, with half of these tumors being benign and the other half being malignant. Again, the tumor causes the adrenals to secrete too much cortisol.
Iatrogenic hyperadrenocorticism: The onset of Cushing’s disease in the form of iatrogenic hyperadrenocorticism occurs due to people giving dogs too much external glucocorticoid. Glucocorticoid can be given to dogs to treat illnesses such as allergies, but when we give too much, the dog’s body is filled with corticosteroid and the dog will develop Cushing’s disease if the treatment is continued.
The most common symptoms that dogs with Cushing’s disease display are:
- Weight gain
- Excessive water consumption
- Excess panting
- Dry coat
- Exercise intolerance
- Skin that heals slowly or damages easily
- Increased urination
Breeds at Risk
While any dog can develop Cushing’s disease, some breeds are more susceptible to the disease. These include:
- Golden Retriever
- Boston terrier
- German shepherd dog
- Scottish terrier
- Other terrier breeds
Additionally, dogs that are in their older years are much more likely to develop Cushing’s disease since older dogs are more likely to develop tumors.
Cushing’s disease can be difficult to diagnose due to the symptoms being common in other endocrine disorders. Some tests your vet might run are:
Urine cortisol: creatinine ratio: This test isn’t used to diagnose Cushing’s disease, but it can rule it out by examining a urine sample for its amount of cortisol to excreted creatinine level. Dogs with a normal ratio are not likely to have Cushing’s.
ACTH Stimulation Test: A blood sample is taken from your dog and saved as a baseline while your vet injects your dog with ACTH. A few hours later, blood is taken again to see how the dog’s adrenal glands reacted to the injection.
Low Dose Dexamethasone Suppression Test: your dog will have fasted and then have its blood drawn to compare with later. Next, the dog is injected with dexamethasone, which is a synthetic glucocorticoid, and have its blood drawn four hours later to see if the dog’s body suppressed the cortisol output like a normal dog, or suppressed it like one with Cushing’s disease would do.
There are different options when it comes to treating your dog. Some owners choose to not treat their dog since treatment can be hard on dogs that are 10 years or older. Some choose surgery to remove the tumors causing the problems if the dog is healthy enough, while others choose drugs such as Lysodren where the dog will be on the medication for life. Make sure to talk with your veterinarian to determine the best option for your dog.