Merck Manual

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Vaccines Required or Recommended for Horses

Vaccines Required or Recommended for Horses

Disease

Description

Vaccination Frequency

Core vaccines

Tetanus

A bacterial infection that attacks the nervous system and causes the muscles to tighten (lockjaw)

First vaccine at 6 months of age, followed by 2 additional vaccinations at 3‑to 6‑week intervals; yearly boosters

Encephalomyelitis (sleeping sickness, Eastern equine encephalomyelitis, Western equine encephalomyelitis)

A family of viral infections carried by mosquitoes that result in inflammation of the nervous system, including the brain

Similar schedule as tetanus (usually given as combination vaccine)

Equine viral rhinopneumonitis

A highly infectious herpesvirus that can cause respiratory disease

Similar schedule as tetanus (usually given as combination vaccine) but semiannual boosters

Influenza

A highly infectious viral respiratory infection; vaccine usually sprayed into the nose

Initial vaccination at 6 to 9 months, followed by revaccination at 11 months; earlier and more frequent vaccination for foals of unvaccinated mares; periodic boosters (for example, every 6 to 12 months)

Other vaccines

Potomac horse fever

A bacterial disease that affects many systems, causing fever, lethargy, diarrhea, and occasionally colic or laminitis (founder); vaccination recommended in areas where disease is common

Initial vaccination at 5 to 6 months followed by revaccination in 4 weeks; booster vaccinations at 1 year and annually after that

Rabies

A viral disease of the nervous system that is both fatal and transmissible to people

Initial vaccination at 6 months of age; boosters at 7 months, 1 year, and yearly after that

Rotavirus

A viral diarrheal disease; vaccination usually restricted to farms with a recurring problem

Pregnant mares are given a 3-dose series of vaccinations before foaling; foals protected through colostrum

Strangles

A bacterial infection of the throat; vaccination usually restricted to farms with a recurring problem

Initial vaccine at 4 to 6 months, followed by 2 revaccinations at 4-week intervals; boosters at 12 months and annually after that

West Nile virus

A viral infection carried by mosquitoes that results in inflammation of the nervous system, including the brain; vaccination currently recommended for horses in continental United States

Initial vaccine at 3 to 4 months, followed by revaccination 1 month later; boosters every 4 to 6 months depending on risk