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PetDosageChart

Vetoryl (Trilostane) Dosage for Dogs

Adrenal steroidogenesis inhibitor ⏱ Onset: 2-4 hours (cortisol reduction) ⏳ Duration: 12-24 hours

This dosage information is for educational purposes only. Always consult your veterinarian before giving any medication to your pet. Dosages may vary based on your pet's health conditions, other medications, and individual factors.

Content reviewed by licensed veterinarians. This information is sourced from veterinary drug references including Plumb's Veterinary Drug Handbook and the Merck Veterinary Manual.

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Vetoryl Dosage Chart for Dogs by Weight

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Weight Low Dose Standard Dose Max Dose Frequency
5 lbs (2.3 kg) 2.5mg 4.5mg (5mg tablet) 7mg Once or twice daily
10 lbs (4.5 kg) 4.5mg (5mg tablet) 9mg (2 × 5mg) 13.5mg Once or twice daily
15 lbs (6.8 kg) 7mg 13.5mg 20.5mg (4 × 5mg) Once or twice daily
20 lbs (9.1 kg) 9mg (2 × 5mg) 18mg 27.5mg Once or twice daily
25 lbs (11.3 kg) 11.5mg 22.5mg 34mg (7 × 5mg) Once or twice daily
30 lbs (13.6 kg) 13.5mg 27mg 41mg (8 × 5mg) Once or twice daily
40 lbs (18.1 kg) 18mg 36mg (7 × 5mg) 54.5mg (11 × 5mg) Once or twice daily
50 lbs (22.7 kg) 22.5mg 45.5mg (9 × 5mg) 68mg Once or twice daily
60 lbs (27.2 kg) 27mg 54.5mg (11 × 5mg) 81.5mg Once or twice daily
70 lbs (31.7 kg) 31.5mg 63.5mg 95mg (19 × 5mg) Once or twice daily
80 lbs (36.3 kg) 36.5mg 72.5mg 109mg (22 × 5mg) Once or twice daily
90 lbs (40.8 kg) 41mg (8 × 5mg) 81.5mg 122.5mg Once or twice daily
100 lbs (45.4 kg) 45.5mg (9 × 5mg) 91mg (18 × 5mg) 136mg (27 × 5mg) Once or twice daily
120 lbs (54.4 kg) 54.5mg (11 × 5mg) 109mg (22 × 5mg) 163mg Once or twice daily
150 lbs (68 kg) 68mg 136mg (27 × 5mg) 204mg (41 × 5mg) Once or twice daily

What is Vetoryl (Trilostane) used for in dogs?

Cushing's disease (hyperadrenocorticism) Pituitary-dependent hyperadrenocorticism Adrenal-dependent hyperadrenocorticism

How to give Vetoryl to your dog

Give trilostane capsules by mouth with food — food significantly improves absorption. Administer at the same time each day. Do NOT open, crush, or break capsules — the drug can be absorbed through human skin and is hazardous to pregnant women. Wear gloves if handling becomes necessary. Give with a full meal for best absorption. Follow your vet's monitoring schedule strictly — ACTH stimulation tests are critical to ensure safe cortisol levels. If your dog shows any signs of lethargy, vomiting, or weakness, stop the medication and contact your vet immediately.

Available Forms

Capsule

Give with Food?

Yes — give with food

Side effects of Vetoryl in dogs

Common side effects

Decreased appetite
Lethargy
Vomiting
Diarrhea

Serious side effects

  • Adrenal necrosis
  • Addisonian crisis (acute cortisol deficiency)
  • Electrolyte imbalances (hyperkalemia, hyponatremia)
  • Sudden death (rare)

When to call the vet

Call your vet immediately if your dog shows any of these signs:

  • Severe lethargy, weakness, or collapse (possible Addisonian crisis)
  • Persistent vomiting or diarrhea after starting or adjusting dose
  • Loss of appetite lasting more than 24 hours
  • Shaking, trembling, or signs of abdominal pain
  • Any sudden change in behavior or energy level

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Vasotec

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Serotonin antagonist and reuptake inhibitor (SARI)

Desyrel

Trazodone

For anxiety

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Janus kinase (JAK) inhibitor

Apoquel

Oclacitinib

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Selective serotonin reuptake inhibitor (SSRI)

Prozac

Fluoxetine

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Sources & References

The dosage information on this page is compiled from the following veterinary and pharmaceutical references:

  • Plumb's Veterinary Drug Handbook — the standard veterinary pharmacology reference used by veterinarians worldwide.
  • Merck Veterinary Manual — a trusted, peer-reviewed resource for veterinary professionals and pet owners.
  • DailyMed (FDA Drug Labels) — official FDA-approved drug labeling and prescribing information for Trilostane.

Frequently Asked Questions

What is Cushing's disease and how does trilostane treat it?
Cushing's disease is caused by the overproduction of cortisol, usually due to a pituitary or adrenal gland tumor. Trilostane works by blocking an enzyme (3-beta-hydroxysteroid dehydrogenase) needed for cortisol production, thereby reducing cortisol levels. It does not cure the underlying tumor but effectively controls symptoms.
What is an ACTH stimulation test and why is it needed?
The ACTH stimulation test measures your dog's adrenal gland response and cortisol levels. It is essential for monitoring trilostane therapy to ensure cortisol is being suppressed to a safe range — not too much (which causes Addison's-like crisis) and not too little (which means the drug isn't working). Testing is typically done 10 days after starting, then at 4 weeks, 12 weeks, and every 3-6 months.
What are the signs of an Addisonian crisis?
If trilostane over-suppresses cortisol, your dog can develop an acute Addisonian crisis with symptoms including severe weakness, collapse, vomiting, diarrhea, shaking, and loss of appetite. This is a life-threatening emergency requiring immediate veterinary care and IV fluids with cortisol supplementation.
Can trilostane capsules be opened and divided?
Trilostane capsules should not be opened or split as the drug can be absorbed through human skin and is particularly dangerous for pregnant women. Handle capsules with care, wash hands after handling, and give the capsule intact. Your vet can prescribe the appropriate capsule size for accurate dosing.
How long will my dog need to take trilostane?
Trilostane is a lifelong treatment for Cushing's disease. It manages symptoms but does not cure the underlying condition. Stopping the medication will allow cortisol levels to rise again and symptoms to return. Regular monitoring visits with ACTH stimulation tests are essential throughout treatment.

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