top of page

All About Vetoryl (trilostane)

Updated: 20 hours ago


What is Vetoryl?


Vetoryl is a prescription drug. It's manufactured by Dechra, a veterinary pharmaceutical company, and is approved by the U.S. Food and Drug Administration (FDA) for the treatment of both pituitary-dependent and adrenal-dependent Cushing’s disease in dogs. The active ingredient in Vetoryl is an enzyme inhibitor called trilostane, which blocks the excessive production of cortisol by the adrenal glands. Vetoryl is available in 5 mg, 10 mg, 20 mg, 30 mg, 60 mg, and 120 mg capsules.


Administering Vetoryl


This medication should be given with food, since food enhances its absorption. It doesn't have to be a large amount. I normally drop the capsules right into my dog’s breakfast. Others give with a scoop of yogurt or peanut butter. You can do whatever works for your dog. Please note that splitting or opening the capsules puts you and your pet at risk and should never be done.


Vetoryl can be administered either once or twice a day. However, studies show that a low dose given every 12 hours may be safer and more effective than a high, once a day dose. Since Vetoryl only remains in a dog’s system for about 12 hours, dosing twice a day is known to control cortisol more consistently.


When giving Vetoryl twice a day, the portions do not have to be equal. For example, a dog on a 15 mg dose would receive 10 mg in the morning and 5 mg in the evening.


Starting Dose


The label for Vetoryl specifies a starting dose of 1 to 3 mg per pound (2.2 to 6.7 mg per kilogram) once a day and advises dog owners to start with the lowest possible dose based on body weight and available capsule sizes.

However, new research has found that dogs should actually be started on a much lower dose than what’s on the label, to lessen the chance for adverse effects. Clinical studies also show that larger dogs are more sensitive to Vetoryl and need less to control their symptoms than smaller dogs. If your dog is just starting this medication, consider dosing at 0.5 to 1 mg per kilogram, every 12 hours. Dogs over 15 kg (33 pounds) should start at the lower end of that range.


The key takeaway: it’s better to begin on a lower dose and work your way up, if needed, than to start on too high of a dose and cause your dog’s cortisol levels to drop too fast. Start low and go slow.


References


Trilostane: Beyond Cushing’s Syndrome (page 5 discusses dosing)



Monitoring Tests & Dose Adjustments


After starting Vetoryl, your dog will need frequent blood tests to measure cortisol levels and make sure he or she is on the right dose. The traditional monitoring test is an ACTH stimulation (stim) test, but some veterinarians use a new method called a pre-Vetoryl cortisol test. Dechra recommends that the ACTH stim test be conducted 4 to 6 hours after a dog is given Vetoryl, with some food, in the morning. However, many vets conduct the test between 2 to 4 hours because this is when the medication reaches its peak effect. Either time is fine, as long as it's the same at every recheck.


For help with interpreting results of ACTH stim tests, see this flowchart.


14 days after starting Vetoryl (trilostane)


The first monitoring test takes place about 14 days after starting Vetoryl (or sooner if a dog becomes unwell). The purpose of the 14-day test is to make sure that your dog’s cortisol level isn’t falling too low. At this point, the veterinarian will determine whether your dog should stay on the same dose or be taken off Vetoryl and restarted at a lower dose. No increase should be made at the 14-day mark, even if symptoms are still present, because cortisol can continue to fall for a month after starting the medication.


30 days after starting Vetoryl (trilostane)


After 30 days on Vetoryl, your veterinarian will recheck cortisol values and clinical signs. The purpose of this visit is to make sure your dog’s dose is sufficient enough to control symptoms but not causing cortisol to be overly suppressed. Sometimes, both the dose and dosing frequency (for example, from once daily to twice daily) need to be adjusted. To minimize the risk of adverse effects, increases in dose should generally be no higher than 25 percent.


Key takeaway: Finding the dose that works best for your dog can take time. There's no one-size-fits-all with Cushing's disease. Anytime a dose adjustment is made, the testing cycle should be started over. This means that cortisol levels should be checked at 10-14 days after the new dose is started and then rechecked at 30 days. If no dose adjustment is needed after 30 days, subsequent tests are recommended every three months thereafter and should include a re-check of electrolytes, kidney values, and liver enzymes.


How long does Vetoryl take to improve symptoms?


It can take up to a month for Vetoryl to reach its full effect. Some signs, such as excessive thirst, tend to improve within a couple of weeks. Other issues, such as hair loss, take more time to resolve.


Potential Side Effects


Vetoryl is generally safe for most dogs, especially if they're started on a low dose. Occasionally, serious side effects, such as over-suppression of the adrenal glands, can occur. If your dog develops any signs of cortisol falling too low, such as vomiting, diarrhea, loss of appetite, or shaking, stop treatment immediately and seek veterinary care. A significant drop in cortisol can rapidly lead to a life-threatening emergency called an Addisonian crisis.


For information about stopping and restarting Vetoryl, please see When to Stop Vetoryl (trilostane): general guidelines.

Precautions for Dogs


Vetoryl should not be given to dogs that have primary liver disease, kidney disease, or are pregnant. Drugs that reduce adrenal function (e.g. aminoglutethimide, ketoconazole, and mitotane), potassium-sparing diuretics (e.g. spironolactone), and potassium supplements should not be used with Vetoryl.


Dogs taking Vetoryl along with ACE inhibitor (e.g. benazepril or enalapril) or ARB (e.g. Telmisartan) should have their electrolyte balances and kidney values periodically checked. In addition to cortisol, Vetoryl reduces a steroid hormone called aldosterone. Since ACE inhibitors and ARBs also reduce aldosterone, taking Vetoryl along with an ACE inhibitor or ARB can cause low aldosterone in dogs and potentially impact electrolyte balance and blood flow to the kidneys.


Precautions for Humans


Wash your hands after handling Vetoryl capsules and never split or open the capsules. Don’t handle Vetoryl capsules if you’re pregnant or planning to become pregnant.


How to Report Side Effects


To report an adverse event associated with Vetoryl, you can either contact the drug company or submit a report to the U.S. Food and Drug Administration (FDA).


References






 
 
bottom of page