⚡ Quick answer: Vetoryl (trilostane) dosage calculator for dogs with Cushing’s disease. Estimate a weight-based starting dose and capsule combination, with essential monitoring and safety guidance.
What Is Vetoryl and What Does It Treat?
Vetoryl is the brand name for trilostane, a prescription medication used to treat Cushing’s disease in dogs — also called hyperadrenocorticism. It is approved for this use by both the FDA and European regulators, and it is the most widely used treatment for the condition.
Cushing’s disease is a hormonal disorder in which the body produces too much cortisol, the main stress hormone. Chronic cortisol excess causes the classic signs owners notice: increased thirst and urination, a ravenous appetite, a pot-bellied appearance, hair loss, panting, muscle weakness and a thinning coat.
Trilostane works by blocking an enzyme (3-beta-hydroxysteroid dehydrogenase) that the adrenal glands need to manufacture cortisol. By turning down cortisol production, it brings the hormone back toward a normal level and relieves the signs of disease.
Here is the single most important thing to understand about Vetoryl: there is no fixed, weight-based “correct” dose. Trilostane is a medication that must be carefully individualised and monitored. The starting dose is only a starting point — the right dose for your dog is found by your veterinarian through follow-up blood testing, and adjusted over time. Too little does not control the disease; too much can cause a dangerous, even life-threatening, cortisol deficiency.
The calculator above provides only an educational starting-dose estimate. Vetoryl must be prescribed, dosed and monitored by a veterinarian. For background, see PuppaDogs’ guide to Vetoryl for dogs and the overview of Cushing’s supplements for dogs.
How the Vetoryl Dosage Calculator Works
The calculator estimates a starting dose from your dog’s weight and the chosen regimen, then:
- Shows the estimated starting dose in milligrams.
- Suggests an example Vetoryl capsule combination (capsules come as 5, 10, 30, 60 and 120 mg).
- Flags health conditions that make trilostane risky.
Enter your dog’s weight, choose a starting regimen, tick any health considerations, then press Estimate Starting Dose. Remember: this is a planning estimate, not a prescription.
How Vetoryl Doses Are Calculated for Dogs
The Starting Dose
The FDA label starting dose for Vetoryl is 2.2–6.7 mg/kg (1–3 mg/lb) once daily, with food. In practice, most veterinarians and specialists now start at the low end of this range, and many — including the authors of recent veterinary guidelines — prefer to split the dose and give it twice daily, often starting near 1 mg/kg every 12 hours. Twice-daily dosing can give smoother cortisol control over the day.
Because trilostane’s effect varies a great deal between individual dogs, the starting dose is deliberately conservative. It is far safer to start low and increase than to start high.
Capsules Must Be Given Whole
Vetoryl is supplied in capsules of 5, 10, 30, 60 and 120 mg. The capsules must be given whole — never opened, split or crushed. If a precise small dose is needed, your veterinarian uses a combination of capsule sizes or a specially compounded preparation. (For handler safety, broken capsules should be avoided, and pregnant women should not handle the contents.)
The Dose Is Set by Monitoring, Not by Weight
This cannot be overstated. After starting Vetoryl, your veterinarian will schedule a recheck around 10–14 days later, and again after any dose change. That recheck typically includes a physical examination, a blood chemistry and electrolyte panel, and an ACTH-stimulation test performed about 4–6 hours after the morning dose. The results — not the dog’s weight — determine the final dose.
Vetoryl Starting-Dose Estimate Chart
This chart shows rough starting-dose estimates only. The real dose is found through monitoring.
| Dog weight | Once-daily start (~2.2 mg/kg) | Twice-daily start (~1 mg/kg per dose) |
|---|---|---|
| 5 kg (11 lb) | ~11 mg | ~5 mg twice daily |
| 10 kg (22 lb) | ~22 mg | ~10 mg twice daily |
| 20 kg (44 lb) | ~44 mg | ~20 mg twice daily |
| 30 kg (66 lb) | ~66 mg | ~30 mg twice daily |
| 40 kg (88 lb) | ~88 mg | ~40 mg twice daily |
How to Give Vetoryl to Your Dog
- Always give with food — this improves absorption and consistency.
- Give at the same time each day, in the morning (and evening, if twice daily).
- Give capsules whole, hidden in a small amount of food.
- Do not give a dose if your dog is unwell — if your dog is not eating, is vomiting, or has diarrhoea, skip the dose and call your veterinarian. This is an important safety habit.
- Keep to the monitoring schedule. The recheck appointments are not optional — they are how the dose is kept correct and safe.
Side Effects and the Most Important Safety Warning
When the dose is correct, many dogs tolerate Vetoryl well and the signs of Cushing’s improve over weeks. Mild side effects can include reduced appetite, mild vomiting or diarrhoea, and lethargy.
The critical risk with Vetoryl is giving too much cortisol-blocking effect, which can tip the body into a cortisol deficiency — a hypoadrenocortical or “Addisonian” crisis. This can be life-threatening.
Stop the medication and contact your veterinarian urgently if your dog shows:
- Marked weakness or lethargy
- Loss of appetite / refusing food
- Vomiting or diarrhoea
- Wobbliness or trembling
- Collapse — treat this as an emergency
These signs can appear even at a dose that previously seemed fine, particularly if the dog is unwell, dehydrated or stressed. The good news is that, caught early, the effect of trilostane wears off relatively quickly once stopped — which is why stopping the drug and calling your vet promptly is so effective.
When Vetoryl Should Be Avoided
Vetoryl should not be used, or used only with great caution under specialist guidance, in dogs that:
- Have kidney disease
- Have liver disease
- Are pregnant or nursing
- Are taking ACE inhibitors or potassium-sparing diuretics (risk of high blood potassium)
Always give your veterinarian a complete medication and health history. Trilostane is one of two main treatments for Cushing’s disease; your vet may also discuss the alternative, mitotane.
Treatment Duration and Monitoring
Cushing’s disease is a chronic condition, and Vetoryl is generally a lifelong treatment. After the initial recheck at 10–14 days, monitoring continues at intervals your veterinarian sets — commonly at around 30 days, 90 days, and then every few months — with ongoing ACTH-stimulation testing and bloodwork. The dose is adjusted as needed throughout the dog’s life. With consistent monitoring, most dogs with Cushing’s disease can be well controlled and live comfortably.
Conclusion
Vetoryl (trilostane) is an effective, approved treatment for canine Cushing’s disease, but it is fundamentally different from a simple weight-based medication. The label starting dose is 2.2–6.7 mg/kg once daily, and many vets now start lower and twice daily — but the starting dose is only a starting point. The calculator above gives an educational estimate; the dose that is actually safe and effective for your dog is found by your veterinarian through ACTH-stimulation testing and regular monitoring. Give capsules whole, with food, never dose a dog that is unwell, learn the warning signs of a cortisol crisis, and keep every recheck appointment — that monitoring is what makes Vetoryl both safe and successful.
Frequently Asked Questions
How much Vetoryl should I give my dog?
There is no single fixed dose. The FDA label starting dose for Vetoryl (trilostane) is 2.2-6.7 mg/kg once daily with food, and many veterinarians now start at the low end or split it as roughly 1 mg/kg twice daily. The starting dose is only a starting point – your vet finds the correct dose through ACTH-stimulation testing and adjusts it over time.
How is the correct Vetoryl dose determined?
The correct dose is found through monitoring, not body weight alone. After starting Vetoryl, your vet schedules a recheck at about 10-14 days that includes a physical exam, blood chemistry and electrolyte panel, and an ACTH-stimulation test done 4-6 hours after the morning dose. The dose is then adjusted based on those results and repeated monitoring.
What are the signs that my dog has had too much Vetoryl?
Too much trilostane can cause a dangerous cortisol deficiency. Warning signs include marked weakness or lethargy, loss of appetite, vomiting, diarrhoea, trembling and, in severe cases, collapse. If you see these, stop the medication and contact your veterinarian urgently – collapse should be treated as an emergency.
Should Vetoryl be given with food?
Yes. Vetoryl should always be given with food, which improves its absorption and gives more consistent results. The capsules must be given whole and never opened, split or crushed. Importantly, do not give a dose if your dog is unwell, not eating, vomiting or has diarrhoea – skip it and call your vet.
How long will my dog need to take Vetoryl?
Cushing’s disease is a chronic condition, so Vetoryl is usually a lifelong treatment. The dose is monitored and adjusted throughout the dog’s life with periodic ACTH-stimulation tests and bloodwork. With consistent monitoring, most dogs with Cushing’s disease can be well controlled and live comfortably.
Can Vetoryl capsules be opened or split?
No. Vetoryl capsules must always be given whole and never opened, split or crushed. If your dog needs a dose between the available capsule strengths (5, 10, 30, 60 and 120 mg), your veterinarian will use a combination of capsule sizes or arrange a compounded preparation rather than splitting a capsule.
Related PuppaDogs Calculators
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References & Further Reading
The dosing ranges and safety information on this page are drawn from the following veterinary references. Always defer to your own veterinarian and the manufacturer’s label for your specific product.
- Vetoryl (trilostane) – FDA-approved veterinary label and prescribing information, Dechra Veterinary Products.
- Plumb DC. Plumb’s Veterinary Drug Handbook. 10th ed. Hoboken, NJ: Wiley-Blackwell, 2023 – trilostane monograph.
- Merck Veterinary Manual. Cushing disease (hyperadrenocorticism) in dogs – medical management. merckvetmanual.com.
- American Animal Hospital Association (AAHA). Monitoring strategies for trilostane therapy in dogs with Cushing’s syndrome. aaha.org.
- PuppaDogs. Vetoryl for Dogs: Benefits, Dosage, Side Effects, and More. puppadogs.com.
⚕️ Medical disclaimer
The information on this page is intended for educational purposes only and does not replace a hands-on veterinary examination. Drug doses depend on your dog’s complete clinical picture, concurrent medications, and the exact product formulation. Always confirm dosing with your veterinarian before administering any medication, and contact a 24-hour veterinary emergency service or animal poison control immediately if you suspect a medication overdose or adverse reaction. PuppaDogs editorial standards: every drug dose published here is cross-checked against multiple authoritative veterinary references and reviewed by the PuppaDogs Veterinary Editorial Team before publication.
