As Ontario’s horse racing regulator, the Alcohol and Gaming Commission of Ontario (AGCO) is committed to protecting the health and welfare of racehorses, which includes ensuring that only horses that are fit to compete are entered into races.
As part of this commitment, the AGCO will now require Thoroughbreds that have not started in more than 365 days, as well as unraced horses aged four years old and older that have not made a start prior to January 1, to undergo an examination and workout with an Official Veterinarian before being eligible to race.
This change is being implemented under Rule 27.08 of the Thoroughbred Rules of Racing, which permits AGCO Veterinarians and Official Veterinarians to add a horse to the Veterinarians' List until it is fit and ready for racing. The decision to implement these new rules was made as a result of a review of evidence that demonstrates an elevated risk of critical injury for these horsesi, ii, iii and aligns with international best practices.
While only a small percentage of horses are expected to be impacted, the evidence suggests that such changes can have a significant impact on improving horse welfare. Placement on the Veterinarians' List allows horses to be examined following a workout and without the use of pain-masking medications, as indicated in Rule 15.40.02.
Advance workouts and trainer options
Trainers can consult with AGCO Veterinary Services to confirm whether their horses will meet these criteria in the near future. To minimize disruption while maintaining oversight of equine health and welfare, trainers will have the option of scheduling an appointment with AGCO Vet Services up to 30 days in advance, helping to avoid interruptions to racing schedules.
Removal of a horse from the AGCO Veterinarians' List
Removal from the Veterinarians’ List is governed by Rule 27.09. Following an examination and workout – and once all conditions stipulated in Rule 27.09 have been satisfied – the AGCO and/or Official Veterinarians may remove a horse from the List if satisfied that they are fit and ready to race.
Other Rules of Racing to note
Trainers are reminded of other rules that support equine health and welfare, including:
- Rule 27.12: AGCO or Official Veterinarians may examine any horse on racetrack grounds, regardless of entry status. The trainer or person in charge will be advised of the examination and its results as soon as reasonably possible.
- Rule 6.35: Horses that have not started in 90 days must complete two workouts before racing. All first‑time starters, including two‑year‑olds, must complete three workouts.
More information
Dr. Adam Chambers
Senior Manager of Veterinary Services
437-533-7835
Dr. Pamela Chesterfield
Manager of Veterinary Services
519-551-1037
- Statistics from the Equine Injury Database (EID)demonstrate that horses four years old and over were more than 15% more likely to suffer fatal injuries over the past five years.
- Epidemiological modeling using EID data in a 2025 analysis identified “making a first start as an older horse” and “age at the current start” as significant risk factors associated with increased likelihood of fatal injury during racing.
- Using the Equine Injury Database, multivariable analysis found higher odds of fatal injury for horses on the Veterinarians’ List and increasing risk with prior injuries and prior scratches/withdrawals.