Cushing's Disease in Dogs & Prednisone Withdrawal

Cushing's disease in dogs is also referred to as hyperadrenocorticism, as it is related to the overproduction of the adrenal hormone cortisol. This disease occurs because of problems with the pituitary or adrenal gland, or as a result of overadministration of corticosteroids like prednisone, causing a variety of unpleasant symptoms. Middle-aged to older dogs are more likely to be affected. Several tests are necessary to determine the cause and type of the disease, as treatments vary.

  1. Types

    • The pituitary-dependent variety of Cushing's accounts for 85 percent of all reported cases. Possible tumors in the pituitary gland or an increased number of normal cells (hyperplasia) causes excessive amounts of adrenocorticotrophic hormone (ACTH) to be released into the body. By contrast, adrenal-dependent cases account for only 15 percent, and are caused by adrenal gland tumors or infections. Occasionally symptoms arise in dogs taking elevated doses of prednisone, causing a temporary form of the disease known as iatrogenic Cushing's.

    Symptoms

    • Many symptoms of Cushing's are nonspecific, meaning they are common for other conditions as well, making this disease difficult to diagnose. Typically, signs like increased drinking, increased urination, pot-bellied appearance, hair-loss or bald spots, weakness, excessive panting, stiffness, difficulty walking or standing, and frequent bladder infections are all possible indicators.

    Diagnosis

    • No single test can diagnose this illness alone. Multiple blood tests are usually required to compare several factors like increased white-blood-cell count, elevated liver enzyme, elevated blood sugar or cholesterol. Urine tests, a complete physical workup, evaluation of the dog's overall medical history and even x-rays also may be conducted.

    Treatment Options

    • Treatment for pituitary-dependent Cushing's often includes adrenolytic agents like mitotane to establish a hormonal balance. Steroid biosynthesis inhibitors (SBI) are another option. Such oral medications are required for the rest of the dog's life, as there is no actual cure for the disease. Most adrenal-dependent cases require surgery to remove the cancerous or affected area, possibly followed by radiation treatments.

    Prednisone Involvement

    • Treatment for dogs with iatrogenic Cushing's includes simply weaning the dosage of prednisone to a level where the body returns to normal function. Prednisone must be tapered slowly and steadily; rapid changes, or ceasing the medication altogether, can be deadly. It is important to work closely with veterinarians during the withdrawal process.

    Considerations

    • Particular breeds may have a predisposition to the disease, including dachshunds, poodles, beagles, Boston terriers and boxers. Middle-aged dogs, especially those with a predisposition, should have annual blood-work done by their veterinarian to establish a healthy baseline for that animal. Any dog exhibiting symptoms should be evaluated by a veterinarian right away, as a better prognosis usually accompanies an early diagnosis.