Vaccines are given to help protect your horse from illness, and giving the appropriate vaccines is an important consideration. With vaccines available for over 15 different diseases and these vaccines being available in over 50 different combinations, selecting the necessary vaccines for your horse can be confusing. The vaccines I select for your horse will vary with the horse’s age, use, travel plans and living quarters, as well as the safety and efficacy of the vaccine.
Following is a brief description of the diseases we will most commonly vaccinate for:
West Nile Virus (WNV): An infection of the brain and spinal cord carried by birds and insects and transmitted to horses mainly by the bite of an infected mosquito. Horses are a ‘dead-end host’ meaning that they cannot transmit the virus to another insect or animal. They can become quite ill if infected, having fever, loss of appetite, listlessness and/ or neurologic problems- weakness, uncoordination, even seizures and death. Over the past few years, approximately 30% of horses with known WNV infections have died. This vaccine is commonly given in the spring, just before the onset of mosquito season, and is repeated every 6-12 months depending on the duration of the mosquito season in the local area.
Eastern Equine Encephalitis (EEE, sleeping sickness): Another viral infection of the brain and spinal cord, with signs similar to WNV. Although cases of EEE haven’t been reported in New Mexico in the recently, the southern United States is currently seeing many horses become infected. This virus is transmitted mainly by biting insects and, unlike WNV, can be transmitted from an infected horse to insects and other horses. An infected horse could introduce infection if transported before showing signs of illness. Again, the vaccine is commonly given in the springtime.
Western Equine Encephalitis (WEE, sleeping sickness): A viral infection similar to EEE and WNV. WEE is diagnosed in horses in New Mexico every year. This virus can be transmitted from horse to horse through biting insects, and can infect humans as well. The vaccine is commonly combined with EEE and given in the spring.
Equine Influenza (EIV): A viral upper respiratory infection easily transmitted from horse to horse by contact with nasal discharge, which can be left on the barn, on tack or a person’s hands, or carried from horse to horse by flies. The duration of protection provided by the vaccine seems to be relatively short (4-6 months), and horses are more susceptible to infection in the cold winter months, so this vaccine is boosted in the fall as well as given in the spring.
Equine Rhinopneumonitis Virus (EHV-1, Equine Herpesvirus): Another viral respiratory infection, EHV can also cause abortion in pregnant mares and can cause neurologic illness. Pregnant mares are vaccinated at 5, 7 & 9 months of gestation to help protect them from infection. Most other horses are vaccinated twice yearly as with EIV. Because of the short duration of protection, horses that travel or are in contact with many other horses are boosted more often.
Tetanus (Clostridium tetani): Tetanus is a bacteria which can normally be found in horse’s intestinal system and manure. Tetanus can cause serious infection of wounds such as nail punctures, wire cuts and other lacerations. The vaccine is commonly given once a year, with an additional booster at the time of an injury.
Rabies: The same viral infection that we are required to vaccinate dogs and cats for, Rabies can infect any mammal, including horses and is still considered fatal once contracted. Livestock species are at risk of infection from wild animals such as skunks, raccoons, foxes, coyotes that wander into their environment. Although not required by law as it is for dogs and cats, Rabies vaccines are made for livestock. Between March, 2008 and 2009, no additional rabies cases were reported in northern New Mexico. Rabies cases continue to occur in southern New Mexico. Because of this and because the American Association of Equine Practitioners (AAEP) has adopted rabies vaccination as one of it’s core recommended vaccinations for horses, I recommend that all horses be vaccinated for rabies annually. Visit my page on Rabies & Horses for more information.
Other vaccines you may have heard about:
Strangles (Streptococcus equi): A bacterial infection most commonly affecting the lymph nodes in the neck, causing swelling and abscessation, which, in the worst case can result in asphyxiation- thus the term ‘strangles’. The bacteria is very hearty, and can live on tack or buildings for many months. Young horses seem to be at most risk of infection, as some natural immunity develops as the horse ages. The vaccine is given most often to young horses, or horses who travel and come in contact with many other horses. The latest vaccines are given intranasally (squirted up the nose). The vaccine occasionally causes a reaction similar to a mild case of infection, with nasal discharge and lymph node swelling.
Venezuelan Equine Encephalitis (VEE): A viral infection similar to EEE, WEE andWNV. VEE is diagnosed in horses in New Mexico occasionally, usually in the southern part of the state. This virus can be transmitted from horse to horse through biting insects. The vaccine, when given, is combined with EEE and WEE and given in the spring.
Potomac Horse Fever (PHF, Ehrlichia ristici): An infection of the GI tract causing fever, inappetance and diarrhea, PHF is not thought to occur in New Mexico but is found throughout the east coast and Midwest. Horses are vaccinated annually, if they will be traveling to areas where this disease occurs.