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Trilostane dose for dogs with Cushing's, monitored by cortisol
Trilostane in dogs starts low, about 0.5 to 1 mg/kg by mouth every 12 hours with food (or 1 to 2 mg/kg once daily), and the Vetinuity trilostane dose table below adjusts it from a pre-pill or ACTH-stimulated cortisol checked at 10 to 14 days, 30 days and 90 days, alongside sodium and potassium.
Trilostane doses at a glance
| Species | Use | Dose | Route and interval |
|---|---|---|---|
| Dog | Twice-daily start | 0.5 to 1 mg/kg | PO every 12 hours with food |
| Dog | Once-daily start | 1 to 2 mg/kg | PO every 24 hours with food |
| Cat | No consensus starting dose | Individual dosing in published case reports | Refer to an internist |
Vetinuity trilostane dose calculator
Why the starting dose is low
The labeled starting doses were once several times higher. Twice-daily low-dose trilostane controlled clinical signs in most dogs in a JAVMA series with fewer adrenal crises1, and the 2023 AAHA endocrinopathy guidelines now start low and titrate up2. Capsules come in fixed strengths, so the calculated dose is rounded down to the nearest capsule or compounded.
Choosing the cortisol test
Two monitoring approaches are in use. The ACTH stimulation test, started 4 to 6 hours after the morning pill, was the original standard. A pre-pill cortisol, drawn before the morning dose, matched clinical control at least as well in a UK study and needs no ACTH3. Whichever is chosen, the result is read with the owner's account of thirst, appetite and energy: a dog that looks well with a cortisol in the target zone stays on its dose, and a dog with persistent polyuria and a cortisol above the zone goes up by about a quarter2.
Electrolytes and the adrenal crisis
Trilostane can overshoot into hypoadrenocorticism. Lethargy, vomiting or diarrhea in a treated dog means the drug is stopped and a cortisol with sodium and potassium is measured that day2. A rising potassium with falling sodium points to mineralocorticoid deficiency as well, which can persist after the drug is withdrawn.
The recheck schedule
Rechecks fall at 10 to 14 days, at 30 days and at 90 days after starting or after any dose change, then every 3 months once stable, each with a cortisol test, electrolytes and a history2. The diagnosis itself should be secure before the first capsule: the 2012 ACVIM consensus describes the tests that establish it4.
Related values on this site: Sodium, Potassium, ALP.
Frequently asked questions
Pre-pill cortisol or ACTH stimulation for trilostane monitoring?
Both are used. Pre-pill cortisol matched clinical control well in one study and avoids the cost of ACTH3.
What should happen if a dog on trilostane becomes lethargic and vomits?
Stop the drug and measure cortisol, sodium and potassium the same day, because trilostane can cause hypoadrenocorticism2.
Is trilostane given with food?
Yes. Absorption is better with a meal, so every dose is given with food2.
Sources
- Vaughan MA, Feldman EC, Hoar BR, et al. Evaluation of twice-daily, low-dose trilostane treatment administered orally in dogs with naturally occurring hyperadrenocorticism. J Am Vet Med Assoc. 2008; 232(9):1321-8. PMID: 18447776. DOI: 10.2460/javma.232.9.1321.
- Bugbee A, Rucinsky R, Cazabon S, et al. 2023 AAHA Selected Endocrinopathies of Dogs and Cats Guidelines. J Am Anim Hosp Assoc. 2023; 59(3):113-135. PMID: 37167252. DOI: 10.5326/JAAHA-MS-7368.
- Macfarlane L, Parkin T, Ramsey I. Pre-trilostane and three-hour post-trilostane cortisol to monitor trilostane therapy in dogs. Vet Rec. 2016; 179(23):597. PMID: 27803375. DOI: 10.1136/vr.103744.
- Behrend EN, Kooistra HS, Nelson R, et al. Diagnosis of spontaneous canine hyperadrenocorticism: 2012 ACVIM consensus statement (small animal). J Vet Intern Med. 2013; 27(6):1292-304. PMID: 24112317. DOI: 10.1111/jvim.12192.