Side Effects of Cushing's Disease Medication in Dogs

Cushing’s Disease, also known as hyperadrenocorticism, occurs in dogs that produce too much of the hormone cortisol. According to the U.S. Food and Drug Administration website, dogs with Cushing’s disease typically experience increased thirst, urination and appetites; hair loss; excessive panting; enlargement of the stomach and decreased activity. Fortunately, there are medications for the treatment of Cushing’s Disease. Such medications are generally safe; however, there are side effects.

  1. Gastrointestinal Upset

    • According to the Pet Place website, medications that are used to treat Cushing’s disease can cause gastrointestinal issues for dogs. Medications such as mitotane and selegiline can cause vomiting and diarrhea. Mitotane can also cause a dog to lose its appetite. If these symptoms are noted, contact your dog’s veterinarian.

    Behavioral Changes

    • Medications to treat Cushing’s Disease can also affect a dog’s behavior. Both mitotane and selegiline can cause a dog to become depressed or lethargic. Mitotane can also cause the dog to become listless or weak. Dogs with Cushing’s disease typically already have decreased energy, however, the medication should be suspected if the energy drops dramatically after the medication is started. In addition, if a dog suddenly has a marked decrease in water consumption, it could be a cause for concern. Decreased water input is a sign that the medication is working, as dogs with Cushing’s disease often drink excessively, but if severe, the veterinarian should be notified.

    Drug Interactions

    • The use of mitotane can interfere with medications the dog currently takes. Dogs on insulin should not take mitotane, as it can reduce the dog’s daily insulin requirements, which makes it more susceptible to hypoglycemia, or low blood sugar levels. In addition, mitotane can cause a reaction with barbituates and spironolactone. Selegiline has the potential to interfere with narcotics and antidepressants. Therefore, inform your veterinarian of any medications your pet is taking before beginning treatment for Cushing’s disease.