Large numbers of horses are congregating these days for spring shows, competitions, and socializing; some of them will bring disease-producing organisms to the events. The best disease protection is a good vaccination program by a veterinarian. Most vaccines require an initial injection followed by a booster within 4 to 6 weeks for maximum protection. The vaccinated horse must be healthy at time of vaccination, the vaccine must be properly refrigerated before it is administered, and the vaccine must be properly injected into the muscle of the horse.

Horses should be exercised only lightly for 3 to 5 days following vaccination, as many will be stiff, sore, or have swelling similar to the “normal” vaccination reaction many humans experience. A veterinarian will choose what vaccines are best, depending on the horse’s age, use, exposure to other horses, and vaccination history.

New vaccines are making life simpler for everyone. Combined vaccines that include coverage for up to five of the most common equine diseases reduce the number of “shots” a horse needs. Intranasal vaccines for influenza and strangles are proving popular and effective; most horses are quite willing to accept them, but some are not thrilled about having them squirted up their nose.

All injectables should be given before giving the strangles spray vaccine to reduce the risk of strep abscesses at the site of injections. Because vaccinations require some time to take effect, the horse will not have immunity immediately after a vaccination. Allow two weeks after vaccination before exposing the horse to other horses that may be carrying a disease.

It is most important to vaccinate against tetanus; the vaccine is effective and safe and has minimal side effects. The Eastern and Western Encephalomyelitis vaccine provides protection against the most common forms of sleeping sickness. Influenza and Rhinopneumonitis are the most common respiratory diseases in horses; boosters every three months may be needed to sustain an adequate level of protection for these two diseases. Vaccines for these five diseases are currently available combined in a single injection.

A rabies vaccine is used more and more often in horses. Rabies is a viral disease of warm-blooded mammals that is universally fatal once symptoms appear. Horses are frequently bitten on the nose due to their curiosity, so the site of infection is uncommonly close to the brain, where the virus causes its damage. Rabies vaccine in horses is given annually.

Other diseases for which vaccines are available include Potomac Horse Fever and Equine Viral Arteritis. Usage depends on risk of exposure. New vaccines are constantly being developed. A veterinarian should provide advice on which ones are appropriate.

– By Dr RD Scoggins