Core vaccinations as those “that protect from diseases that are endemic to a region, those with potential public health significance, required by law, virulent/highly infectious, and/or those posing a risk of severe disease. Core vaccines have clearly demonstrated efficacy and safety, and thus exhibit a high enough level of patient benefit and low enough level of risk to justify their use in the majority of patients.” The following equine vaccines meet these criteria and are identified as ‘core’ in these guidelines:

Equine Rabies

Rabies is an infrequently encountered neurological disease. While the incidence of rabies in horses is low, the disease is invariably fatal and has considerable public health significance. It is recommended that rabies vaccine be a core vaccine for all equine. Exposure occurs through the bite of an infected (rabid) animal, typically a wildlife source such as raccoon, fox, skunk, or bat. Bites to horses occur most often on the muzzle, face, and lower limbs. The virus migrates via nerves to the brain where it initiates rapidly progressive, invariably fatal encephalitis.


All horses are at risk of development of tetanus, an often fatal disease caused by a potent neurotoxin elaborated by the anaerobic, spore-forming bacterium, Clostridium tetani. Tetanus toxoid is a core equine vaccine and is indicated in the immunization program for all horses. Clostridium tetani organisms are present in the intestinal tract and feces of horses, other animals and humans, and are abundant as well as ubiquitous in soil. Spores of Cl. tetani survive in the environment for many years, resulting in an ever-present risk of exposure of horses and people.

Eastern/Western/Venezuelan Equine Encephalomyelitis

In the United States, equine encephalitides for which vaccines are available include eastern equine encephalomyelitis (EEE), western equine encephalomyelitis (WEE), Venezuelan equine encephalomyelitis (VEE) and West Nile Virus encephalomyelitis. Transmission of EEE/WEE/VEE is by mosquitoes, and infrequently by other bloodsucking insects, to horses from wild birds or rodents, which serve as natural reservoirs for these viruses. Human beings are also susceptible to these diseases when the virus is transmitted to them by infected mosquitoes.

West Nile Virus

West Nile virus (WNV) is the leading cause of arbovirus encephalitis in horses and humans in the United States. Since 1999, more than 25,000 cases of WNV encephalitis have been reported in U.S. horses. Horses represent 96.9% of all reported non-human mammalian cases of WNV disease. West Nile virus is transmitted by many different mosquito species and this varies geographically. The virus and mosquito host interactions result in regional change in virulence of the virus; therefore, no prediction can be made regarding future trends in local activity of the viruses. The case fatality rate for horses exhibiting clinical signs of WNV infection is approximately 33%. Data have supported that 40% of horses that survive the acute illness caused by WNV still exhibit residual effects, such as gait and behavioral abnormalities, 6 months post-diagnosis. Thus vaccination for West Nile virus is recommended as a core vaccine and is an essential standard of care for all horses in North America.

Rhino (EHV-1/EHV-4)

Equine herpesvirus type 1 (EHV-1) and equine herpesvirus type 4 (EHV-4) infect the respiratory tract, the clinical outcome of which can vary in severity from sub-clinical to severe respiratory disease. Clinical infection is characterized by fever, lethargy, anorexia, nasal discharge, cough, and mandibular lymphadenopathy. Both EHV-1 and EHV-4 spread primarily by the respiratory route, by direct and indirect (fomite) contact with nasal secretions.


Streptococcus equi subspecies equi (S. equi var. equi) is the bacterium which causes the highly contagious disease strangles (also known as “distemper”). Strangles commonly affects young horses (weanlings and yearlings), but horses of any age can be infected. Vaccination against S. equi is recommended on premises where strangles is a persistent endemic problem or for horses that are expected to be at high risk of exposure. The organism is transmitted by direct contact with infected horses or sub-clinical shedders, or indirectly by contact with water troughs, hoses, feed bunks, pastures, stalls, trailers, tack, grooming equipment, nose wipe cloths or sponges, attendants’ hands and clothing, or insects contaminated with nasal discharge or pus draining from lymph nodes of infected horses.


Equine influenza is highly contagious and the virus spreads rapidly through groups of horses in aerosolized droplets dispersed by coughing. The severity of clinical signs depends on the degree of existing immunity, among other factors.

What is a Coggins test for a horse?

The Coggins test checks for Equine Infectious Anemia (EIA) antibodies in the horse's blood. This test is often needed to take your horse to a show and whenever you transport your horse across state lines.

What is (EIA) Equine Infectious Anemia?

Equine infectious anemia (EIA) is a horse disease caused by a retrovirus and transmitted by bloodsucking insects. The virus is a lentivirus, like human immunodeficiency virus (HIV). Like HIV, EIA can be transmitted through blood, milk, and body secretions. Transmission is primarily through biting flies, such as the horse-fly and deer-fly. The virus survives up to 4 hours in the carrier. Contaminated surgical equipment and recycled needles and syringes, and bits can transmit the disease. Mares can transmit the disease to their foals via the placenta. The risk of transmitting the disease is greatest when an infected horse is ill, as the blood levels of the virus are then highest.


Keep your horses healthy by working with your veterinarian to develop a program to help protect against parasites and diseases.

  • Any horse that grazes is at risk for parasite infection. Other risk factors for parasite infection include any place horses commingle — such as boarding stables or competitions.
  • Tapeworms and small strongyles can cause extensive internal damage, which can lead to colic.
  • Nationwide, more than 50% of horses test positive for tapeworm exposure.