Vaccines are an integral part of the health maintenance of horses. However, today's veterinarians and owners are cognizant of the potential negative effects of over vaccination and strive to use vaccines on the most safe and efficient schedule possible.

There are currently no available vaccines for Eastern and Western Encephalitis only. While the addition of tetanus is convenient for some, for others it is causing problems. In areas with long fly seasons, twice yearly encephalitis vaccination is recommended and the tetanus is an unnecessary antigenic burden. Owners with horses prone to exaggerated vaccine reactions wish to avoid multivalent vaccines in favor of vaccinating for one disease type at a time with several weeks rest in between. Horses that have received a tetanus vaccine because of an injury might not require another when their encephalitis protection is scheduled.

Optimal scheduling can also be problematic for broodmares foaling very early in the year. When mares are vaccinated prepartum there is a real risk of residual maternal antibodies interfering with the extra early vaccine recommended in the southeastern states or maternal antibody waning before the usual 4 to 6 month age first vaccination. If mares are not vaccinated prepartum, the recommended age of foals for tetanus vaccinations is different from that for encephalitis.

There is a very real need and demand for an Eastern/Western Encephalitis vaccine that does not include tetanus. It is a win-win situation with an established market waiting for the company stepping up to fill this niche and veterinarians/caretakers/owners finally receiving a long overdue tool for better health care.