According to a study published in the Journal of Veterinary Pharmacology and Therapeutics, betamethasone, a corticosteroid, remains detectable above thresholds published by the Horseracing Integrity and Safety Authority for 23 days after administration of 12 mg IM. The study also found that IM betamethasone use suppressed the horse’s cortisol levels for 360 hours, or 15 days. Cortisol is the primary stress hormone in equines.
Source: Paulick Report, March 3, 2026. Link. Betamethasone is currently FDA-approved for intra-articular use in horses, so IM use is considered off-label.
This study is another helpful reminder that route of administration, among other factors like dose and frequency, impacts how long a substance is present in the horse’s body and thus how long it can be detected in a sample following administration.”
Image: Link.