By the time a human infant reaches 4 months of age he or she has likely received a battery of vaccinations, starting shortly after birth. In contrast, four- to six-month-old foals whose dams were vaccinated properly are likely just starting to receive immunizations, as recommended by the American Association of Equine Practitioners’ (AAEP) vaccination guidelines.

But what about foals born later in the year, in the midst of mosquito season? Should owners wait to vaccinate them until they reach four to six months of age? New research suggests that earlier vaccination—and, thus, earlier disease protection—might help ensure foals are well-protected against mosquito-borne disease.

At the 2013 AAEP Convention, held Dec. 7-11 in Nashville, Tenn., Elizabeth Davis, DVM, PhD, Dipl. ACVIM, presented research results indicating that veterinarians can begin providing foals protection against disease via vaccination sooner than once thought. Davis is a professor and section head of equine medicine and surgery at Kansas State University’s College of Veterinary Medicine.

In most cases, foals’ born to well-vaccinated mares aren’t vaccinated until maternal antibodies—which provide immune protection to the foal, but can also inhibit the foals’ ability to respond to vaccinations—contained in the mare’s colostrum wane to a sufficient level), typically within six months after birth. Therefore, the AAEP currently recommends starting to vaccinate these foals for tetanus, Eastern and Western equine encephalomyelitis (EEE and WEE), West Nile virus (WNV), and equine herpesvirus (EHV) at 4 to 6 months of age, and rabies and influenza at 6 months of