Spring is the classic time of year for booster vaccinations on horses.
Most veterinarians will recommend a 4-way or 5-way vaccine as a standard for most horses. Diseases for which these vaccines provide protection include tetanus, eastern equine encephalomyelitis, western equine encephalomyelitis, equine influenza (flu) and for the 5-way, rhinopneumonitis (rhino). Additionally, vaccinating for west nile virus and rabies are considered core vaccinations that should be administered to basically every horse.
Tetanus: This an often fatal disease brought on by the organism clostridium tetani. This organism is a normal inhabitant of equine feces and can survive for long periods of time in the environment posing a constant risk of exposure. Typically, infection starts in an open wound that is contaminated. The vaccine is considered very safe and effective.
EEE/WEE: Eastern and Western Equine Encephalomyelitis viruses cause disease affecting the central nervous system of the horse. This results in neurologic symptoms including aggression and excitability, propulsive walking, circling and at times, paralysis of the tongue and inability to swallow. These diseases often come with significant mortality rates. Transmission is most commonly from birds or rodents to horses via mosquitoes.
Flu: Equine Influenza virus causes respiratory disease in horses and is a highly contagious disease that is spread through aerosolized particles, allowing it to spread rapidly from one horse to another. Typically, the horse’s own immune system will clear the infection in a matter of several days, however, because of the highly contagious nature of the disease, vaccination is recommended.
Rhino: Equine Herpes Virus causes respiratory disease in horses (commonly called rhinopnemonitis) and can also cause abortion in mares and more rarely, neurologic disease as well. Most combination vaccines target protection against the respiratory component of the disease. Close horse-to-horse contact is the means by which the disease is spread. Like other herpes viruses the disease can establish latency in the horse and re-emerge during periods of stress. Vaccination is recommended for horses at risk of exposure to other horses.
West Nile: West Nile Virus (WNV) causes neurologic disease in the horse and is transmitted most commonly from infected birds to horses via mosquitoes, similar to EEE/WEE. Horses are considered dead end hosts for WNV and transmission from horse to horse or horse to human has not been shown to occur. WNV has been identified all across the U.S. Vaccination is highly effective.
Rabies: Rabies is caused by a virus and infection results in fatal neurologic disease in horses. Rabies is not common in horses but horses are at risk of exposure to wildlife reservoirs such as raccoons, skunks and/or foxes. Given the fact that the disease is invariably fatal and potentially transmissible to humans, vaccination is recommended.
For all vaccines, follow label recommendations for administration and dosing and consult with your local veterinarian for suggested vaccination protocols specific to your horse.
Darren Loula, DVM, is a large animal veterinarian at Fair Grove Vet Service in Fair Grove, Mo.
