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Trilostane (Cushings Disease) Therapy

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For dogs with hyperadrenocorticism caused by a pituitary tumor, there are now two medication options for treatment. Each has drawbacks and risks, and neither drug is 100% effective. Both drugs are costly and both require blood testing to monitor for problems and to adjust the dose of medication to fit what is needed by the dog.

Vetoryl (trilostane) benefits:

*Longer life expectancy
*Slightly greater efficacy – 90% of dogs will respond vs. 80% for Lysodren
*Treats secondary hyperparathyroidism – calcium and phosphorus imbalances
that may occur in dogs with Cushing’s disease.
*Can be used for adrenal tumors as well as pituitary tumors.
*Can be used in cats and ferrets.
*Also treats atypical Cushing’s disease, in which other adrenal hormones besides
cortisol are affected. (This typically occurs in Scotties and ferrets.)
*Less risk of hypoadrenocorticism than Lysodren.
*Milder side effects than mitotane.

Vetoryl (trilostane) drawbacks:

*Greater chance of sudden death shortly after starting on the medication. If they
do well on it they usually live longer than dogs on Lysodren do, but they can also
die suddenly early on.
*The side effects tend to be milder but are also more common. Side effects
include hypoadrenocorticism, acute adrenal gland necrosis (cell death),
hypercalcemia (elevated calcium level) and hyperkalemia (elevated potassium
level). 64% of dogs will have vomiting, diarrhea or lethargy.
*Can be toxic to humans. Wash hands after handling these pills, and wear gloves
when handling these pills if you are pregnant.
*It’s dangerous to try Vetoryl first and then try mitotane. If you want to try one
drug at a time, try the mitotane first.

Lysodren (mitotane) benefits:

*80% effective
*We’ve been using it for years and are more comfortable with managing side
effects if they do occur.

Lysodren (mitotane) drawbacks:

*Can cause toxicity and some dogs cannot tolerate the side effects, such as
vomiting and diarrhea. 25% of dogs treated will develop one or more side
effects, including lethargy, weakness, poor appetite, vomiting or diarrhea.
*Life expectancy is shorter than for dogs on Trilostane
*Relapse is possible
*About 5% of treated dogs develop hypoadrenocorticism and need lifetime
medication for that disease instead – so instead of making too much of the
adrenal hormones they no longer make enough. This in and of itself can be life
*May affect insulin dose in diabetic patients.
*As with trilostane, it can be toxic to humans. Wash hands after handling these
pills, and wear gloves when handling these pills if you are pregnant. 


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