Canine Cushing's disease is a condition often found in dogs ages 7 and older. Cushing's dogs suffer from overactive adrenal glands producing excessive amounts of the stress hormone cortisol. Cushing's often results from pituitary or adrenal gland tumours. Symptoms include excessive thirst and hunger, hair loss and pot belly.
Traditional Cushing's treatment include the removal of the affected gland (adrenalectomy) followed by a lifelong course of prednisone, and medication to destroy affected adrenal tissue. Some dog owners also use alternative remedies.
In cases of benign adrenal tumours, adrenalectomy of the affected gland is recommended. Dogs have two adrenal glands, and in most cases the second one continues to function normally. Because Cushing's can interfere with the healing process, many dogs are given a course of ketoconazole in advance of their surgeries to reduce their Cushing's symptoms. Adrenalectomy carries the risk of several complications. Pancreatitis, infection, bleeding and imbalances of fluids and electrolytes are possible. Dogs that have both adrenal glands removed will need permanent prednisone supplementation. Dogs that have only one gland removed will eventually produce enough cortisol to be weaned off postoperative prednisone. Dogs may also undergo laparoscopic surgery to remove adrenal glands with malignant tumours that have not entered the vein known as the vena cava.
Lysodren is the medication most commonly prescribed for dogs with pituitary-related Cushing's. It destroys the overactive portion of the adrenal gland. The dog goes though an induction phase with daily doses of Lysodren for 7 to 10 days. The dog is tested, and if its cortisol levels are normal, the vet will prescribe a maintenance dosage of Lysodren. Most dogs need Lysodren only once or twice weekly.
Dogs unresponsive to Lysodren may be treated with Anipryl, which has no effect on adrenal tissue. Anipryl raises pituitary levels of dopamine, in turn lowering the pituitary's production of ACTH. ACTH stimulates adrenal release of cortisol, so less ACTH means less cortisol and better-controlled Cushing's symptoms. Anipryl is the only medication with FDA approval as a canine Cushing's treatment.
Ketaconazole is an anti-fungal medication with the side effect of lowered adrenal hormone prodouction, suitable for treating both pituitary and adrenal related Cushing's. Because it also lowers sex hormones, it is recommended only for neutered and spayed animals. It's administered for a 1-week induction phase, and if the animal responds, it can be continued indefinitely.
Trilostane controls Cushing's by inhibiting an enzyme essential to cortisol production. After an introductory phase to determine a safe dosage, Trilostane is usually given with food one or two times per day.
A dog on either Trilostane or Lysodren must be tested regularly to ensure that the medication has not destroyed too much adrenal tissue. Insufficient adrenal tissue leads to insufficient cortisol production resulting in hypoadrenocoticism, also known as Addison's disease.
Homeopathic remedies are formulated for individual dogs to treat specific Cushing's symptoms instead of using a generic treatment for the disease itself. Two homeopathic remedies from "The Complete Holistic Dog Book" are arsenicum and hepar, useful in treating thirst and skin, abdominal and liver problems. This book also recommends ginseng, dandelion root, astralagus and burdock as herbal remedies for Cushing's.
A list of American holistic vets familiar with alternative Cushing's treatments is available online at the AHVMA website.
Dogs with iatrogenic Cushing's are slowly taken off the steroid medications they're receiving for other medical problems. The symptoms of the other problems almost always resurface.