Part one: Equine biosecurity – what does it mean?

Moderator’s note: This is the first in a three part series on equine biosecurity. Part two will be posted Thursday and part three will be posted Friday.

By James Little, DVM

Equine and companion animal professional services veterinarian


Biosecurity is a word that we often see written and hear spoken by various people ranging from university researchers to government officials. But what does it mean to horse owners and enthusiasts?

People who have an interest in the equine industry are likely aware of infectious disease outbreaks. Neurologic equine herpes virus (EHV) outbreaks have resulted in several equine deaths, temporary closings of various facilities, and varying degrees of panic among horse owners. Strangles outbreaks are not uncommon, and although they don’t receive the same publicity, still result in economic losses to the horse owner, not to mention the suffering of the horse itself. These are only a couple of outbreak examples. For background purposes, infectious means capable of causing infection. In our discussion here, I am referring to diseases that are caused by infectious microorganisms (e.g., bacteria, viruses). Contagious refers to a disease that can be transferred from one animal to another.

In the best sense of the word, biosecurity is a term that describes a plan to prevent introduction of infectious disease into a population. The only true way to prevent infectious disease is to prevent exposure of the animal to the disease-causing organism. In the equine world, this population could be anything from a horse or group of horses at a veterinary clinic, equine event or a horse farm. In the real world, we want to use good biosecurity practices to not only prevent but to also limit the spread of disease to other animals once an infectious disease has made its way into a population/herd. To do this we have several tools in our biosecurity toolbox that we can use. Hopefully we are already using some of these tools but just didn’t realize we were practicing biosecurity. With that said, there are others tools that may need to be pulled out of the toolbox and implemented.


Vaccines are excellent tools to help prevent infectious disease. When administered to the horse, a vaccine stimulates an immune response (immunization) against a specific infectious organism.  For horses, we strive to go by the recommendations made by the American Association of Equine Practitioners (AAEP). They divide vaccines into two categories— core and risk-based. Core vaccines are those that immunize against infectious diseases that every horse may potentially be exposed to, produce severe disease, or may be able to be passed on to humans. The core vaccines include eastern and western encephalitis, tetanus, West Nile, and rabies. The risk-based vaccines include those that an individual horse may be at risk for depending on several factors including but not limited to its geographical location, exposure to other horses, and age. These vaccines include botulism, EHV, equine influenza, anthrax, Potomac horse fever, rotavirus, strangles and equine viral arteritis. It is important, and this is not just vet talk, to consult with your veterinarian to complete a risk analysis for your horses and determine which vaccinations are warranted.

Vaccines, however, are not intended to be, nor can they be, the only disease prevention strategy used. First, we do not have a vaccine for every infectious disease. Some examples include the neurologic form of EHV, Salmonella, and pigeon fever. Also, individual horses respond to vaccines differently. In other words, an individual horse’s immune system will respond better to a vaccine and develop a better immunity level than other horses for various reasons. Furthermore, a horse’s immune system can be overwhelmed if its exposure level to a particular infectious organism is too high. The take home message is that vaccines are an integral and essential part of a biosecurity plan but cannot solely be relied upon.

Check back tomorrow for the next post in this series — isolating and grouping horses.

Check back Friday for the last post in the series –rodent/insect control and cleaning and disinfecting.

For previous posts from Dr. Little, click here.

Comments are closed.