Extracted from: Considerations for Vaccination, by Dr. Pat Meyersin the Mohill Farm Mangement publication,
available from the Equine research Centre

In most horse operations, vaccination forms an integral part of the overall preventive health program for infectious disease.To use or not to use a particular type of vaccine in a certain situation is a question that is often asked of veterinarians. This decision depends on the risk/benefit analysis of the particular disease in question. Benefits of not acquiring a significant disease situation on farm are rather obvious. In performance horses, the goal of the preventive health program is to minimize or even eliminate the time spent out of training in order to maximize earning potential. Risk of acquiring a disease depends on all of the factors that contribute to the likelihood of a horse getting that disease.

Other important considerations include effectiveness of the vaccine, its cost and potential side effects. Under these considerations, there exists a wide range of vaccination scenarios. For instance, an adequately vaccinated performance horse may derive much more significant economic benefit from an optimal period of rest than a barren broodmare or a "backyard" horse. On the other side of the coin, many owners of "backyard" horses will diligently vaccinate their horse against even low-risk diseases despite the expense involved in order to keep their horse healthy.

Currently, there are vaccines available to aid in the prevention of the following diseases: tetanus, eastern, western, venezuelan encephalomyelitis, influenza A-equi-1 and A-equi-2 equine herpes 1 and 4 infection, strangles, rabies, Potomac horse fever, botulism, equine viral arteritis, anthrax.