Article Text


Pre-trilostane and three-hour post-trilostane cortisol to monitor trilostane therapy in dogs
  1. L. Macfarlane, BVMS DipECVIM-CA MRCVS1,
  2. T. Parkin, BSc, BVSc, PhD, DipECVPH, FHEA, MRCVS2 and
  3. I. Ramsey, BVSc, Phd, DSAM, FHEA, FRCVS, DipECVIM-CA3
  1. 1North Downs Specialist Referral, Friesian Buildings 3&4, The Brewerstreet Dairy Business Park, Brewer Street, Bletchingley, Surrey RH1 4QP, UK
  2. 2Weipers Centre Equine Hospital, University of Glasgow, Glasgow, UK
  3. 3Small Animal Hospital, University of Glasgow, Glasgow, UK
  1. E-mail for correspondence: Lmacfarlane{at}


It is recommended that trilostane therapy of canine hyperadrenocorticism is monitored using an ACTH stimulation test, however this has never been validated. Three cortisol concentrations (pre-trilostane, 3-hour posttrilostane and 1-hour post-ACTH stimulation) were compared to a clinical score obtained from an owner questionnaire. There were 110 sets of 3 cortisol measurements and questionnaires obtained from 67 trilostane treated dogs. Questionnaire results were used to classify each dog as well or unwell. Well dogs were then categorised as having excellent, moderate or poor hyperadrenocorticism control, using thresholds produced by 14 independent veterinarians. Correlation co-efficients were used to compare the three cortisol concentrations to the owner score and the Kruskal Wallis and Mann-Whitney U tests were used to compare the three cortisol concentrations between categories of control. Cortisol cut-off values between significantly different categories were determined using ROC curves. Pre-trilostane and 3-hour post-trilostane cortisol were better correlated to the owner score and had cut-offs to differentiate between categories of control that had superior sensitivity and specificity results, than the post-ACTH cortisol. Iatrogenic hypoadrenocorticism was not detected in any unwell dog. This study shows that the pre-trilostane and 3-hour post-trilostane cortisol are potentially better monitoring methods than the ACTH stimulation test.

  • Trilostane
  • Hyperadrenocorticism
  • Monitoring
  • Canine
  • ACTH stimulation
  • Pre-trilostane

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:

View Full Text

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.