Know When to Vaccinate Foals for Best Protection

After nearly a year of waiting, it's finally here. Your new foal has hobbled into the world. Do you know which vaccinations your gangly new friend needs to help stay healthy?

"Starting a foal off on the right foot with preventive care to help protect it against equine disease actually begins with the broodmare," says April Knudson, DVM, equine specialist for Merial's Large Animal Veterinary Services. "With broodmares, it is best to give booster vaccinations approximately 30 days before foaling. This ensures the mare has a high level of antibodies in her colostrum, which are then passed on to her foal through the milk shortly after birth."

"While horse owners may not be aware of instances of equine diseases in their communities, they do exist," says Knudson. "Helping protect newborn foals against them is critical as they can be deadly or financially devastating."

Assuming the mare has received the appropriate shots in the suggested timeframe, the American Association of Equine Practitioners (AAEP) recommends vaccinating the newborn foal for tetanus, Eastern/Western equine encephalomyelitis (EEE/WEE), rabies, and West Nile virus (WNV). Most vaccination schedules begin when the foal is four to six months old and are given initially as a series, followed by annual revaccination.

Tetanus, which is fatal in at least 50% of equine cases, can be caused by everyday manure, dirt, or rust contaminating a puncture wound. EEE and WEE are common causes of equine encephalitis. Transmitted to horses by mosquitoes, EEE is fatal in 90% of cases. WNV, identified in nearly 10,000 mosquito pools in 2011 and confirmed in 83 horses nationwide in 2011, is fatal in one out of every three cases. Rabies, the final disease for which the AAEP always recommends vaccination, is nearly always fatal.

"Because of the variability of climates and other conditions, we suggest horse owners work closely with their veterinarians to determine when the core vaccines should be given and which of the risk-based vaccines need to be considered," says Knudson.

Once a foal receives his or her initial round of vaccinations, it's important to keep them up to date, notes Knudson. "Vaccinations should not be allowed to lapse as the horse then loses the immunity the vaccines were originally intended to provide and can be susceptible to disease. A timely vaccination schedule is an important part of an overall health care plan."

Horse owners should consult with their veterinarians regarding the specific dosing timetable. With an additional vaccination for rabies, foals will have received all core vaccinations as recommended by the AAEP.

For more information about the entire line of Merial equine vaccines, visit

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