Horse Vaccines in 2012: Where We Stand

As winter ends and spring begins, most horse owners start thinking about vaccinations. Which ones should my horse receive? How often should he be vaccinated? Does he need any risk-based vaccines? Confused? Don't worry. One equine veterinarian and researcher distilled the broad topic of vaccinations down at the 2012 Western Veterinary Conference, held Feb. 19-23 in Las Vegas, Nev.

"The decision to vaccinate horses should depend on risk of infection and scientific evidence that a vaccine will reduce that risk," explained Elizabeth G. Davis, DVM, PhD, Dipl. ACVIM, associated professor and equine section head at the Kansas State University College of Veterinary Medicine.

Davis began by cautioning that no vaccine can--or should be expected to--prevent all disease. Rather, she explained that vaccines are designed to protect and boost the horse's immune system in the face of challenge from an infectious pathogen. Davis discussed the ins and outs about how vaccines protect the horse (by eliciting an immune response against a familiar pathogen), how vaccine antigens are handled within the body, and the types of immune response triggered (humoral or cell-mediated) before delving into the decision making process behind choosing vaccinations.

She suggested practitioners and owners alike follow the recommendations set forth by the American Association of Equine Practitioners (AAEP) in their vaccination guidelines.

AAEP Core Vaccines

"Core vaccines should be provided for all horses in the United States," Davis said. She explained that the vaccines are considered "core" if they protect against a common disease that all horses are at risk of developing and if the disease is often or always fatal if contracted, and include:

  • Equine encephalomyelitis (Eastern, Western, and Venezuelan);
  • Rabies;
  • Tetanus; and
  • West Nile virus.

Davis recommended following the dosing schedule included in the AAEP guidelines with the understanding that owners located in milder climates will often vaccinate before those located in cooler climates.

AAEP Risk-Based Vaccines

"Risk-based vaccines should be considered as a result of potential for disease exposure and the impact of that disease on the horse or environment," Davis said. Because age and vocation dictate the need for a risk-based vaccine, Davis recommended consulting with a veterinarian on which risk-based vaccines each individual horse should receive. These vaccinations include:

  • Anthrax;
  • Botulism;
  • Equine herpesvirus-1 and 4 (EHV-1/4; these vaccines have not been proven to protect against the neurologic form, she noted. Good biosecurity practices, she said, are the best method of protection against the neurologic form.);
  • Equine influenza (EIV);
  • Equine viral arteritis;
  • Potomac horse fever;
  • Rotavirus; and
  • Strangles.

Davis also discussed a melanoma vaccine currently being tested in equine patients. While the vaccination is not yet ready for use in the general horse population, she reported favorable results thus far in the testing process. She noted the vaccine will likely be expensive due to the fact an oncologist must administer the inoculation via a gene gun.

"We should use risk-based vaccines as dictated by need," she stressed. "For example, all horses should be vaccinated for EIV and EHV-1/4 to protect against respiratory disease, but the frequency will be based on risk of exposure such as a horse that is used for pleasure purposes (possibly vaccinate one to two times annually) compared to a show horse (possibly vaccinate three to four times annually)."

Take-Home Message

Horse owners in 2012 have all the resources needed to ensure a properly vaccinated horse. Reviewing the AAEP's vaccination guidelines to brush up on knowledge of the different options before discussing protocol with a veterinarian can help simplify what could be a tedious process.

"It is essential to include the equine practitioner in the vaccine decision-making process," Davis stressed. "These are the experts who can help make the most appropriate decisions to help keep horses healthy, and they can also help avoid overvaccination."

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.

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