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Equine Vaccination

August 24, 2013

By Dr. Debra Taylor, (334) 844-4490

Auburn, Alabama —

The “core” vaccines are for the prevention of diseases that horses may acquire from contact with environmental risk factors such as mosquitos, bacteria in the soil and wildlife.  There are five “core” vaccines that are recommended for all horses; three of them prevent viral encephalitis (Eastern, Western and West Nile virus encephalitis), the other two prevent Tetanus and Rabies.   Each of these diseases can produce life threatening untreatable illness in unvaccinated horses.  None of these diseases are contagious between horses, yet for the affected individual horse, the chance of survival is not favorable. 

The three viral encephalitidies (Eastern, Western and West  Nile viruses) are spread by mosquitos who have acquired the virus from an infected bird.  Horses that acquire Eastern or Western Encephalitis have very little chance of survival.  West Nile encephalitis carries a bit better prognosis for survival (50- 60%).  However, treatment may be expensive and some affected horses may not survive the infection despite treatment.  Vaccination to prevent these three viral diseases is safe and very effective.

Tetanus is caused by the contamination of a wound with the bacteria Clostridium tetani.  Clostridium tetani is found in the soil and in horse manure.  Horses are very sensitive to toxins that are produced when this bacteria grows within a wound or a foot abscess.  Tetanus is a severe condition that is often fatal despite aggressive treatment efforts.  There are two products on the market for the prevention of tetanus, tetanus toxoid and tetanus antitoxin.  Tetanus toxoid is a safe, inexpensive and effective vaccine for the prevention of tetanus.  Tetanus toxoid is commonly combined in vaccines with Eastern, Western and West Nile encephalitis.   Routine administration of tetanus toxoid circumvents any need for administration of tetanus antitoxin (which has underlying risk associated with its use).

Rabies is caused by a virus that is spread by the bite of an infected animal.  Although horses are not required to have rabies certificates as are small animals, the Southeastern United States is endemic for rabies and therefore horses living in our region are at risk of infection and should be vaccinated annually.  

Routine vaccination is a safe, effective and low cost method of preventing horses from acquiring these 5 devastating diseases from their environment.   Your veterinarian can help you design a “core” vaccination program that best suits your horse’s age and previous vaccination history.

“Risk based” vaccines: “to vaccinate or not to vaccinate” and “with which product”?

There is a longer list of “risk based” vaccinations (see below).  The decision to vaccinate for these diseases is based on the level of risk that your horse will be exposed to one of these diseases. Diseases within this list can be subdivided into two categories; 1) diseases which are contagious from horse to horse and 2) environmentally acquired regional diseases. 

Diseases which are contagious from horse to horse

  • Rhinopneumonitis
  • Influenza
  • Strangles
  • Equine Viral Arteritis

Environmentally acquired regional diseases

  • Botulism
  • Potomac Horse Fever

 Once we have moved beyond the topic of “core” equine vaccines, there is less concensus among veterinarians and scientists regarding the selection and use of the currently available vaccines for many of these “risk based” diseases.   The lack of complete “concensus” stems from the following;  1) vaccines for diseases of this category (other than Botulism) have a tendency to be less effective than those in the “core” list, 2) there is a multitude of different vaccine technologies on the market for some of these diseases (i.e. all vaccines are not created equal), and 3) there is great need for further research in these areas of equine disease prevention.  Equine owners should consult their veterinarian to better understand which products are most appropriate for different situations and to better understand the most effective use of the various vaccines that are available. 

Vaccination against the one or more of the diseases which are spread from horse to horse (Rhinopneumonitis, Influenza, Strangles and Equine Viral Arteritis) should be given consideration whenever horses are grouped together in large or transient groups.  This includes horses stabled in boarding, training and breeding facilities and those being hauled to shows, events and trail rides.  Owners should be aware that even if they do not haul their own horse to shows and events, if another horse on the farm is coming and going from the farm, then all the horses on the farm are at increased risk of these diseases.  Regardless of their exposure to transient populations of other horses, all broodmares should be vaccinated for rhinopneumonitis during the 5th, 7th and 9th months of pregnancy with a product that is labeled for use in pregnant mares for the prevention of EHV-1 induced abortion.  

Owners should recognize that prevention of diseases which are spread by horse to horse contact requires more than vaccination.  Prevention of these diseases also requires an understanding of methods to prevent exposure and transmission by minimizing horse to horse contact and fomite contact.  Furthermore it is essential to maximize individual horse immunity through good nutrition, internal parasite control and by minimizing stress associated with training and shipping.

Additional information on prevention of each of these diseases can be obtained from consultation with your veterinarian and from the American Association of Equine Practitioners website.  ( )

To schedule a vaccine consultation with one of our equine clinicians you may call 334-844-4490.

Auburn University | College of Veterinary Medicine | Auburn, Alabama 36849 | (334) 844-4546
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