Medroxyprogesterone acetate (MPA) is a synthetic progestin hormone administered to mares off-label in an attempt to suppress behavioral estrus. However, a controlled research study found that MPA was not effective at suppression of behavioral estrus.1 Many veterinarians believe MPA modifies behavior by producing a calming effect in the horse and does not have a therapeutic benefit that goes beyond this behavior modification. Therefore, the AAEP recommends that MPA should not be administered to horses in competition.
1. Gee EK, C DeLuca, JL Stylski, PM McCue. Efficacy of medroxyprogesterone acetate in suppression of estrus in cycling mares. J Equine Vet Sci 2009;29:140-145.
Currently under review.
Related Resources
Client Education Presentation: Colic
Owner education events can be a great venue to improve the daily…
Position on the Use of Therapeutic Medication in the Racehorse
The AAEP policy on medication in pari-mutuel racing is driven by our…
Position on the Judicious Use of Antimicrobials
Antimicrobial agents are necessary to manage infectious diseases in horses, but adverse…