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Adrenal steroidogenesis inhibitor · For Dogs

Vetoryl dosage reference for dogs (Trilostane)

This page's standard weight-based reference is 2 mg per kg (0.91 mg per lb), with Once or twice daily recorded as the reference frequency. Use the calculator to see the arithmetic for your dog's weight, then confirm the indication, product, and actual dose with a veterinarian.

Onset
2-4 hours (cortisol reduction)
Duration
12-24 hours
Class
Adrenal steroidogenesis inhibitor

Weight-based calculator estimate from the references listed on this page. This page has not been independently DVM-reviewed — see our methodology .

This information is for educational purposes only. Always consult your veterinarian before giving medication to your pet. Do not use this calculator for emergencies, overdoses, pregnancy, very young animals, very old animals, pets with liver/kidney disease, or pets taking multiple medications.

Each medication page lists the references recorded for its data. The calculator math and editorial presentation are maintained by PetDosageChart; a page is independently DVM-reviewed only when a named reviewer byline appears. See our methodology and limitations.

Trilostane (often known by brand names such as Vetoryl) is an adrenal steroidogenesis inhibitor commonly used in veterinary medicine for Cushing’s disease (hyperadrenocorticism), Pituitary-dependent hyperadrenocorticism, and Adrenal-dependent hyperadrenocorticism. Understanding the correct dosage, administration, and potential side effects of Trilostane is critical for your dog’s safety and well-being.

A typical Trilostane dose for dogs is around 2 mg/kg Once or twice daily, within a usual range of 1-3 mg/kg. Available forms include Capsule.

Calculator Warning: Use this only as an educational estimate. Your veterinarian may prescribe a different dose based on your pet’s condition, age, weight, other medications, and medical history.

Trilostane Dosage Calculator for Dogs

Enter your dog’s weight below to estimate the Trilostane dose from the 2 mg/kg guideline. Your veterinarian may adjust it for your dog’s age, condition, and other medications, so treat the result as an educational starting point, not a prescription.

Dosage Calculator · 01

Enter your dog's weight

Quick Dosage Chart

Typical Trilostane amounts for common dog weights, for quick reference:

Dosage Chart · 02

Vetoryl weight-based reference chart for dogs

Scroll sideways to see full table

Weight Lower Reference Standard Reference Upper Reference Frequency
5 lbs (2.3 kg) 2.3 mg 4.6 mg (5mg tablet) 6.9 mg Once or twice daily
10 lbs (4.5 kg) 4.5 mg (5mg tablet) 9.0 mg (2 × 5mg) 13.5 mg Once or twice daily
15 lbs (6.8 kg) 6.8 mg 13.6 mg 20.4 mg (4 × 5mg) Once or twice daily
20 lbs (9.1 kg) 9.1 mg (2 × 5mg) 18.2 mg 27.3 mg Once or twice daily
25 lbs (11.3 kg) 11.3 mg 22.6 mg 33.9 mg (7 × 5mg) Once or twice daily
30 lbs (13.6 kg) 13.6 mg 27.2 mg 40.8 mg (8 × 5mg) Once or twice daily
40 lbs (18.1 kg) 18.1 mg 36.2 mg (7 × 5mg) 54.3 mg (11 × 5mg) Once or twice daily
50 lbs (22.7 kg) 22.7 mg 45.4 mg (9 × 5mg) 68.1 mg Once or twice daily
60 lbs (27.2 kg) 27.2 mg 54.4 mg (11 × 5mg) 81.6 mg Once or twice daily
70 lbs (31.7 kg) 31.7 mg 63.4 mg 95.1 mg (19 × 5mg) Once or twice daily
80 lbs (36.3 kg) 36.3 mg 72.6 mg 108.9 mg (22 × 5mg) Once or twice daily
90 lbs (40.8 kg) 40.8 mg (8 × 5mg) 81.6 mg 122.4 mg Once or twice daily
100 lbs (45.4 kg) 45.4 mg (9 × 5mg) 90.8 mg (18 × 5mg) 136.2 mg (27 × 5mg) Once or twice daily
120 lbs (54.4 kg) 54.4 mg (11 × 5mg) 108.8 mg (22 × 5mg) 163.2 mg Once or twice daily
150 lbs (68 kg) 68.0 mg 136.0 mg (27 × 5mg) 204.0 mg (41 × 5mg) Once or twice daily

Parenthetical tablet amounts are arithmetic comparisons only. They do not account for scoring, release type, concentration, product labeling, or whether this medication is appropriate for an individual animal.

By Weight

Vetoryl reference by dog weight

Choose a common weight to open its optional reference page. Use the main medication calculator for a different exact weight.

Common-weight pages are convenience views of the same educational reference, not separate medical recommendations.

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How to Give Trilostane 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.

It is generally recommended to give Trilostane with food to help reduce stomach upset. It may interact with ACE inhibitors (increased risk of hyperkalemia), Spironolactone (contraindicated — can cause adrenal necrosis), Potassium supplements, and NSAIDs.

Side Effects and Safety

Common side effects include Decreased appetite, Lethargy, Vomiting, and Diarrhea. More serious side effects can occur, such as Adrenal necrosis, Addisonian crisis (acute cortisol deficiency), Electrolyte imbalances (hyperkalemia, hyponatremia), and Sudden death (rare).

Cautions · 12

When Vetoryl should be used with caution or avoided

Some dogs should not take Vetoryl, or need a different dose and closer monitoring. Tell your veterinarian about your pet's full health history and every other medication or supplement they take before giving Vetoryl.

  • Liver disease
  • Kidney disease
  • Dogs taking spironolactone or ACE inhibitors without monitoring
  • Known hypersensitivity to trilostane

Interactions · 13

Vetoryl drug interactions

Vetoryl can interact with other drugs. This list is not complete — always give your veterinarian a full list of your dog's medications and supplements.

ACE inhibitors (increased risk of hyperkalemia)
Spironolactone (contraindicated — can cause adrenal necrosis)
Potassium supplements
NSAIDs

Calculator Limits · 14

When not to use this calculator

This calculator gives a general educational estimate for a healthy adult dog at a known weight. Do not rely on it in these situations — talk to your veterinarian instead:

  • In an emergency, or after accidental ingestion or a suspected overdose
  • For pregnant or nursing pets
  • For very young or very old dogs
  • For pets with liver disease, kidney disease, or another chronic illness
  • For pets taking several medications at once
  • When you are not sure of your dog's current, accurate weight
  • For combination products that contain additional active ingredients

Overdose · 15

Suspected overdose: what to do

If you think your dog had too much Vetoryl, or swallowed any medication by accident, act right away. Do not wait for symptoms to appear.

  • Call your veterinarian or the nearest emergency animal hospital.
  • ASPCA Animal Poison Control Center: (888) 426-4435
  • Pet Poison Helpline: (855) 764-7661

A consultation fee may apply to the poison hotlines. Have the medication packaging ready, and note how much your pet may have taken and when. Do not try to make your pet vomit unless a veterinarian tells you to.

When to Call the Vet

If your dog experiences any of the following, contact your veterinarian or an emergency clinic immediately:

Frequently Asked Questions

Frequently Asked · 07

Questions about this medication

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.

Use This Guide Safely · 08

What weight alone cannot tell you

The calculator performs one narrow job: it multiplies your dog's weight by the lower, standard, and upper mg/kg values recorded for Vetoryl. It cannot decide whether this drug, indication, formulation, or schedule is appropriate for an individual animal.

Context in this medication record

Commonly listed uses
Cushing's disease (hyperadrenocorticism), Pituitary-dependent hyperadrenocorticism, Adrenal-dependent hyperadrenocorticism
Recorded forms
Capsule
Reference timing
Once or twice daily; onset 2-4 hours (cortisol reduction); duration 12-24 hours

Individual checks a calculator cannot perform

  • Confirm the diagnosis and the reason this medication is being considered.
  • Match the exact product, concentration, route, and whether a tablet may be split.
  • Account for age, pregnancy, organ function, genetics, allergies, and prior reactions.
  • Review every prescription, over-the-counter product, and supplement your pet takes.

Recorded cautions

Liver disease; Kidney disease; Dogs taking spironolactone or ACE inhibitors without monitoring; Known hypersensitivity to trilostane.

Recorded interactions

ACE inhibitors (increased risk of hyperkalemia); Spironolactone (contraindicated — can cause adrenal necrosis); Potassium supplements; NSAIDs.

These lists reproduce the structured record used by this page and may not be exhaustive. Show your veterinarian the product label and your dog's complete medication list before acting on a number.

Related · 08

Related medications for dogs

Sources · 09

Sources & references

The structured medication record behind this page names the references below. The links open the publisher or official resource; they do not turn this page into a prescription for an individual animal.

Source names are shown at the record level; passage-level page and label citations are still being added. Read our methodology and limitations.

Transparency · 11

How this page was made

This page's structured medication record includes Plumb's Veterinary Drug Handbook among its source names. PetDosageChart applies the record's mg/kg values to the entered weight and presents the arithmetic result. A source record is not the same as an individualized prescription or an independent clinical review.

Sources cited
  • Plumb's Veterinary Drug Handbook
  • Merck Veterinary Manual
Calculator formula
Doses scale linearly from a standard basis of 2 mg per kg (0.91 mg per lb) of body weight, given Once or twice daily. The calculator multiplies that basis by your dog's weight and shows an arithmetic comparison with recorded tablet sizes. That comparison does not determine whether a tablet is scored, splittable, or appropriate for your pet.
Editorial owner
Prepared and maintained by the PetDosageChart editorial team, a software-led publisher and not a veterinary practice.
DVM review status
Not independently DVM-reviewed. A named reviewer and review date appear here only after a confirmed review.

More on our methodology and editorial process — how we source, calculate, and review dogs dosage data.

Safety · 10

More resources