This document provides guidelines for trilostane treatment of canine pituitary-dependent hyperadrenocorticism. It recommends starting trilostane at 2 mg/kg every 24 hours or 1 mg/kg every 12 hours. Clinical response and ACTH stimulation test results after 10-14 days determine if the dose should be decreased, maintained, or increased. The ACTH stimulation test should check cortisol levels 4-6 hours after administration and the results should fall within an ideal range provided by the reference laboratory.

1. M a n a g e m e n t T r e e / ENDOCRINOLOGY Peer Reviewed
Ellen Behrend, VMD, PhD, Diplomate ACVIM
Auburn University
Trilostane Treatment for Canine
Pituitary-Dependent Hyperadrenocorticism
Trilostane
• 2 mg/kg Q 24 H OR • 1 mg/kg Q 12 H
• Decreased appetite, vomiting, diarrhea, listless-
ness or water intake < 60 mL/kg Q 24 H
OR
• After 10–14 days of treatment
• Run ACTH stim test beginning 4–6 H after
trilostane administration
• Check with your reference laboratory for “ideal
range”; it is approximately 30–150 nmol/L or
1–5 mcg/dL pre- and post-ACTH stim testing
Response below ideal Response ideal Response above ideal
• Discontinue for 2–3 days Clinical signs Clinical signs Clinical signs
• Restart medication at 25% controlled present present
lower dose
• Recheck ACTH stim test in 7
days
OR • Continue • On day 30 or • If on recheck ACTH stim test at
• Recheck ACTH stim test in 3 therapy beyond? If giv- day 10–14, cortisol concentra-
days • Recheck ACTH ing Q 24 H, tions are lower or clinical signs
• Restart medication at 25% stim test at 30 then halve the improved, then maintain dose
lower dose when cortisol level days and, if dose and give and recheck ACTH stim test
is ideal or higher doing well, at Q 12 H again at day 30
90 days; then • Recheck ACTH
every 90–120 stim test after
days, if signs 10 days
recur, or if signs
of cortisol insuf- • If recheck ACTH stim test results
ficiency are still above ideal after > 30 days
present on therapy or at day 10–14 no
improvement was noted,
See Aids & Resources, increase dose 25%; recheck
back page, for references ACTH stim test in 7 days
& suggested reading.
Investigation Treatment
ACTH = adrenocorticotropic hormone, stim = stimulation
Diagnosis Result
This algorithm can be downloaded from cliniciansbrief.com and printed for use in your clinic.
32 ........................................................................................................................................................................NAVC Clinician’s Brief / June 2011 / Management Tree