Q:Can you address off-label use of the rabies vaccine in late-term broodmares? My therio vet won’t give it because it's off-label usage. So I arrange for another vet in her practice to vaccinate my late-term mares. I cannot imagine my foals not having that protection from his or her first moments. There is nothing more curious than a foal–and investigating that skunk or raccoon in their pasture is nearly a given. Waiting until 3 months to give that protection just seems incredibly reckless. It also seems to me that giving a vaccine off-cycle and in such a narrow window between breed-backs opens the door for the vaccine getting missed.

A: Rabies vaccination can be administered in the last trimester of pregnancy prior to delivery to protect the foals, although your veterinarian is correct, it is off-label use. Mares that are vaccinated prior to breeding are generally considered to pass adequate antibodies to foals in their colostrum as well. Foals have excellent maternal antibodies to protect them from this disease if the mare has been vaccinated and they have consumed adequate colostrum. Actually, studies have shown that foals of vaccinated mares will not mount an adequate response to vaccination if they are immunized before 6 months of age, due to maternal antibody interference.

Learn more about rabies and read more Q&A with Dr. House in our free on-demand webinar: Equine Rabies: What Every Horse Owner Should Know!