BHA Notices Section
Detection Times for Intra-Articular Corticosteroids
The Equine Science and Welfare Department of the British Horseracing Authority would like to draw the attention of Trainers to the use of intra-articular corticosteroids in racehorses, close to raceday. The Authority is concerned both that withdrawal times used based on historical practice may not be adequate and that some Trainers' veterinary surgeons may even be using shorter withdrawal times than suggested by this historical practice.
The Association of Racecourse Veterinary Surgeons surveyed the use by racing practitioners of this and other medications in 2004. This survey provided some useful information but highlighted considerable variation and was limited. Regarding intra-articular medication for example, the survey results did not include a note of concurrent administration of other products, dose used, joint(s) injected or clinical details.
When corticosteroids are administered by any route, particularly into joints, there is potential for considerable variation in excretion times. The site injected, dose used, degree of inflammation and presence or absence of additional medications contribute to this, and in turn render the task of publishing a 'cover all' Detection Time extremely difficult. However, generically, in lieu of scientific, harmonised data being available, and following consideration of currently available analytical, in vivo experimental and clinical data with other racing authorities, we would advise trainers, that whilst no Detection Time has been published for intra-articular Triamcinolone acetonide we are aware of several studies in normal horses that would indicate to us that if a total dose of 10 mg Triamcinolone acetonide alone were injected intra-articularly on one occasion, the Detection Time would be unlikely to exceed 10 days.
There is a need to consider individual variation according to circumstances in deciding individual Withdrawal Times. The site injected, dose used, degree of inflammation and presence or absence of additional medications is likely to affect Detection Time. In particular we are aware of preliminary data from clinical studies where the Detection Time for intra-articular Triamcinolone acetonide in horses with joint disease was considerably in excess of 10 days. Further work on Triamcinolone acetonide pharmacokinetics in normal joints was published in 2011 in the American Journal of Veterinary Research (Volume 72 pages 1234-42.
The difference between a Detection Time and a Withdrawal Time should be understood. Detection Times are not synonymous with Withdrawal Times. To decide a Withdrawal Time an adequate safety margin must be added to the stated Detection Time. This safety margin must be chosen by the treating veterinary surgeon using his professional judgment and discretion, to allow for biological, pharmaceutical and pharmacological variation. Clearly in these matters discussion between a Trainer and their veterinary surgeon is essential.
If there is any doubt regarding whether a horse is clear to race, Trainers are invited to contact the Authority for advice and/or the facility for Elective Testing.