It’s that time of year again - shots! Administering vaccines to your horse allows the body to prepare itself to fight off potential diseases by developing a gradual immunity to the disease-causing agent. Depending on where you live, vets will recommend to administer a five-way booster, covering rabies, tetanus, West Nile Virus, as well as Eastern and Western Encephalomyelitis.
Rabies is a deadly virus which is passed through the saliva of animals infected with the disease, which is most commonly found in wildlife. According to the American Association of Equine Practitioners, only 30-60 horses contract rabies in the United States on average per year. Symptoms include lethargy, eating and drinking less, and becoming depressed. Once these clinical signs are present, the mammal typically dies 3-5 days after becoming infected.
Tetanus, commonly called Lockjaw, is the infection of an anaerobic bacteria (Clostridium Tetani) going into the bloodstream and tensing the muscles of the horse and spreading throughout the rest of the body. It can be contracted through open wounds- lacerations, puncture wounds, and incisions, and commonly seen in horses who have been in contact with rusty nails in their stall and turnout area. It can also be passed through the feces of an infected animals. The most common symptom to look for is muscle tenseness, such as a prolapse of the horse’s haw (protective eyelid), muscle spasms, and extreme sensitivities to touch. In the United States, there has been little documentation of the disease. Fewer than 5 horses in 2018 contracted tetanus in Ontario, Canada (AAEP). If left unvaccinated, the infected horse’s chance of surviving is slim, usually only carrying the neurotoxin for a week before the body shuts down. More information on vaccination dosage, varying based on the age of the horse, can be found here.
West Nile Virus was first contracted in 1937, in Uganda, showing few symptoms prior to the rapid decline of the mammal. The primary vector are mosquitoes. West Nile Virus shuts down the central nervous system, damaging both the brain and spinal cord. The disease spread to the Eastern coast of New York, finally reaching the United States in 1999. In 2002, there were nearly 15,000 horses that contracted the virus. The host of the disease is the infected bird, in which the mosquito takes in the infected bird’s blood and then transfers it to the horse when it bites into the horse. More information on statistics and origin of West Nile Virus can be found here.
Eastern Encephalomyelitis, commonly known as Sleeping Sickness or Triple E, is a virus that also damages the central nervous system in the horse and whose primary vectors are mosquitoes as well. Songbirds along the Northeastern coast, such as in New Jersey, are common reservoirs. EEE is more common than Western Encephalomyelitis in the United States; the first documented outbreak being in 1951 in Louisiana. Affected horses die within three days of contracting either Encephalomyelitis. Horses are highly susceptible in wooded, rural areas where mosquitoes are populous and feeding. EEE present in horses does not require them to be quarantined, and they cannot transmit the disease to other horses. It is important to also take action to protect yourself from mosquitoes, as humans have been known to contract EEE as well, although it is not comm. More information on vaccination dosage, varying based on the age of the horse, can be found here.
Additionally, veterinarians recommend giving risked-based vaccines dependent on the region and the percentage of risk associated with contracting the disease in that specific region. Some examples include respiratory illnesses, such as Equine Influenza, or Rhinopneumonitis. The risk for contracting these diseases increases as the air quality of the surrounding region worsens. It is up to the judgement of local veterinarians to decide whether or not to vaccinate for the potential risk of your horse contracting that disease. Consult your veterinarian first for guidance when choosing which additional vaccines to administer in your local area.