Trilostane is one of only two prescription drugs that the U.S. Food and Drug Administration has approved to treat Cushing's disease in dogs. Pups with Cushing's disease produce too much cortisone, a type of hormone that is synthesized in the adrenal glands. To treat Cushing's disease, your vet may prescribe Trilostane for your pooch, a drug that inhibits an enzyme that the pup's body uses to produce cortisol.
Too Much of a Good Thing
Cortisol is a steroid hormone that helps your pup's body adapt to stress, but too much of it is actually a bad thing and can weaken his immune system and even cause death. While some cases of Cushing's disease are caused by a tumor in the adrenal glands, most cases are triggered by a tumor in the pituitary gland, which is found at the base of the brain, according to the Washington State University College of Veterinary Medicine. The pituitary gland can stimulate the adrenal glands to produce cortisol. Trilostane treats, but does not cure, both adrenal-dependent and pituitary-dependent Cushing's disease. For this reason, it is usually administered for the rest of your pup's life.
How Trilostane Works
Trilostane stops your pooch's adrenal glands from producing excessive amounts of steroid hormones, including cortisol, by blocking the enzyme 3-beta-hydroxysteroid dehydrogenase. This enzyme is vital for the production of these adrenal hormones, so without it, your pup's cortisol levels will decrease to more normal levels. Trilostane is an oral medication that you give to your pup once or twice each day, as directed by your vet and is only available by prescription. Unlike other medications, such as the human chemotherapy drug lysodren, which is often used "off label" to treat canine Cushing's disease, trilostane doesn't permanently damage the adrenal cortex to stop the production of cortisol.
What to Expect With Trilostane
Trilostane isn't without potential side effects, which include weakness, lethargy, vomiting, diarrhea and a loss of appetite in the first few days of using it. More serious symptoms like collapse, bloody stool or severe depression can also occur. In some cases, a permanent or life-threatening reaction can occur, in which the adrenal glands stop working properly and not enough cortisol and other hormones are produced. This is known as an Addisonian reaction because your pup will suddenly develop Addison's disease, which is caused by a lack of cortisol in the body, the opposite of Cushing's disease. While most effects of trilostane are reversible if you stop giving it, others, like adrenal damage, may not be.
Speaking With Your Vet
Follow your vet's directions when administering trilostane to your pup because too much or too little of the drug can be dangerous for Fido. Usually, this medication is given with food. Trilostane isn't recommended for pregnant pooches or those suffering with kidney or liver problems, warns the FDA. This medication may also negatively interact with some heart medications. Observe your pup for any unusual side effects, which may mean that Fido is allergic to trilostane. Bring your pup to the vet as she directs to monitor his blood work so that she can adjust your pooch's dose of trilostane, if necessary.