Treatment For Cushing's Disease In Dogs
Depending on the cause of hyperadrenocorticism (Cushing's disease) in your dog, several different treatment options are available. Treatment for Cushing's disease is also heavily dependent on how well your dog would be able to handle surgery, or other procedures that will put significant stress on your dog's system. Some treatment options involve chemotherapy, which may not be feasible for older or very ill dogs.
Withdrawal Of Glucocorticoids
If your dog has iatrogenic hyperadrenocorticism, treatment is fairly simple. Since this type of Cushing's disease is caused by over-administration of glucocorticoids due to treatment of a chronic condition, treatment simply involves the gradual withdrawal of the glucocorticoids. With the subsequent decrease of corticosteroids in your dog's system, the adrenal glands will eventually begin to function normally once again.
This is a treatment that is usually used for adrenal-based hyperadrenocorticism. In this treatment procedure,
the dog undergoes an operation to remove the adrenal gland tumor, as well as the affected adrenal gland. In
most cases, this is able to "cure" adrenal-based hyperadrenocorticism, since the tumor (if benign)
usually doesn't manifest in the remaining adrenal gland.
However, since one of the symptoms of Cushing's disease is slow healing of wounds, this procedure must be done with extreme care. Prior to surgery, some dogs are given ketoconazole which sometimes helps to minimize symptoms of Cushing's disease.
Since roughly half of adrenal gland tumors are malignant, however, it's possible that the tumor has metastasized to other organs such as the lungs or liver. Most adrenal tumors aren't discovered in time to perform surgery, mostly due to the lengthy diagnosis required by most cases of Cushing's disease. Also, some older dogs may not survive this procedure, so many dog owners choose an alternate form of treatment.
In the roughly 80-85% of cases of Cushing's disease where it is pituitary-dependent, Lysodren
is the most popular, and most effective treatment.
To treat Cushing's disease, Lysodren targets the outer layer of the adrenal glands, also called the "cortex". With regular administration of Lysodren, the cortex tissue of the adrenal gland is gradually destroyed, usually in about a week of daily Lysodren treatments. The damaged adrenals are not able to respond as effectively to the over-secretion of ACTH by the pituitary gland, so blood cortisol levels subsequently drop.
After a dog's blood cortisol levels are within a normal level, they must be given Lysodren for the rest of their lives to maintain their condition. The danger with Lysodren is that the adrenals may incur too much damage, which would result in below-normal blood cortisol levels, also known as Addison's disease.
Ketaconazole is usually used in dogs that don't respond to Lysodren treatment. It can be used to treat both adrenal-based and pituitary-dependent hyperadrenocorticism. Ketaconazole is an anti-fungal medication that also suppresses hormone production. Though safer to use than Lysodren, approximately 25% of dogs do not respond to this method of treatment.
This treatment method has been approved for treatment of Cushing's disease in dogs, though it's effectiveness is highly debated. Anipryl decreases the production of ACTH by increasing levels of dopamine. The decreased ACTH levels will cause a drop in cortisol levels in pituitary-dependent cases of hyperadrenocorticism. Though clinically approved for use as a treatment for Cushing's disease, many veterinarians claim that it is only 15-40% effective.