Race-Day Veterinary Check

Yes, but it is not necessarily done the day of the race - the vet check may be the day before the race. Once the vet check has been performed, then a sign is hung on the stall saying the horse is quarantined until race day, meaning only authorized people (groom, vet, trainer) can enter the stall.

Then there are vets in attendance at the starting gate to scratch any horse that does not 'look right' during warm-up or to gate-scratch any horse that acts up in the gate and gets in trouble.