Horses are herbivores that have been used historically for agricultural work and transportation. The main types of horses are categorized as draft-type (Percherons, Suffolks, Clydesdales, etc.), hot-bloods (Arabians, Thoroughbreds, Saddlebreds, etc.), ponies (Shetlands, Hackneys, Welsh, etc.) and related equine species (mules, donkeys, burros, etc.). The horse industry today is diverse and contributes significantly to the economic health of the state. Horse enthusiasts enjoy a wide range of activities such as trail riding, rodeos, racing, show competitions, jumping, driving, and hunting.

Equine Infectious Anemia (EIA)

Equine Infectious Anemia is an acute or chronic viral disease of equidae. The virus is related to the human AIDS Lentivirus, but is not known to infect humans. The predominate means of spread is the intermittent feeding of biting insects, especially horse flies and deer flies. EIA can also be spread through indiscriminate use of hypodermic needles, blood transfusions, and use of contaminated instruments or tack. No specific treatment or vaccine is currently available.

In Missouri, equidae must be tested for EIA when they are involved in a change-of-ownership, when they are imported from another state, when they are publicly exhibited, boarded, trained, bred, and when they are sold through a livestock market. Discovery of disease requires quarantining and retesting of the affected and exposed animal(s). Upon confirmation of positive test results from the USDA National Veterinary Services Laboratory, the affected animal is permanently identified and either sold for slaughter, euthanized, or permanently quarantined to the owner’s premises until natural death occurs.

For further information, please contact the Division of Animal Health at (573) 751-3377, or e-mail

West Nile Virus

West Nile is a viral disease that usually affects birds, people and horses. It is spread by mosquitoes and is generally seen in Missouri during the mid July thru October time period. The past several years have seen a very low incidence in the Midwest, but this year there have been several cases reported in the surrounding states and two positive horses in Missouri. The horses initially appear depressed and generally develop neurologic signs, such as an inability to stand or a staggering gait, as the disease progresses. Contact your veterinarian immediately if you notice these symptoms in your horses.

Horse owners should consult their veterinarians regarding the best vaccine to use to prevent the disease in your horses. Horses that were vaccinated early in the spring may require a booster in the late summer or fall.

For further information, please contact the Division of Animal Health at (573) 751-3377, or e-mail