A disease-related “perfect storm” occurs when risk factors and a pathogen successfully interact, resulting in the introduction and spread of an infectious organism among a susceptible population. In the world of equine events, a perfect storm is plausible if:
- Susceptible, stressed horses are exposed to an infectious disease agent;
- The conditions and environment at the even support transmission and infection; and
- The pathogen rapidly spreads throughout the animal population.
In May 2011, horses that attended the National Cutting Horse Association event in Ogden, Utah, were exposed to equine herpesvirus-1 (EHV-1). A number of these horses developed EHV-1 myeloencephalopathy. The disease likely spread due to multiple high-risk practices such as commingling horses of unknown health statuses, stabling horses in close proximity, horse being tied to fences outside of the arena, use of shared water sources, use of communal wash racks, and exercising horses in confined spaces. The resulting outbreak garnered national attention and serves as an example of a perfect storm that had a significant impact on the equine industry.
Most equine event venues and facility layouts allow exhibitors easy, direct access to competition/exhibition areas. Under such circumstances, many shows have inadequate or non-existent isolation facilities for horses displaying signs of disease. To address this concern, starting in December 2017, the US Equestrian will require that competition management have an isolation protocol for horses suspected of having an infectious disease.
Isolation of clinically affected horses is a critical first step in disease outbreak control. It is essential to identify potential areas for isolation of sick horses in an area away from the remainder of the equine population. Due to the lack of appropriate isolation areas at many events, consideration must be given to the construction of a temporary pipe corral type/isolation pen in a parking lot or an off-side area. Vacant horse stables, livestock facilities, supply sheds, or local fairgrounds may be available for use in these situations. Advanced identification of appropriate alternate stabling facilities will allow for rapid isolation of a sick horse and decrease the risk of potential disease transmission.
In addition to adequate isolation, observance of basic biosecurity practices are necessary to prevent pathogen introduction and spread. Routine biosecurity practices should limit or avoid:
- Horse-to-horse contact;
- Human contact with multiple horses;
- Use of shared communal water sources; and
- Use of shared equipment that has not been cleaned and disinfected between uses.
Additionally, daily monitoring of horse health on the event grounds should include twice-daily temperature evaluations and observation for clinical signs of disease. Horses with a temperature above 101.5°F or that exhibit clinical signs should be reported to a veterinarian and/or event official and be immediately isolated away from all other horses.
A biosecurity toolkit of equine events has been developed to provide guidance on the development and implementation of biosecurity plans and isolation protocols. The toolkit can be found at cdfa.ca.gov/ahfss/Animal_Health/Equine_Biosecurity.html. The toolkit provides guidance for the assessment and development of a biosecurity plan that addresses specific disease risks at a particular event and venue. Implementation of a biosecurity plan for every equine event will help protect the health of the national equine population.
CONTACT—Katie Flynn, BVMS—firstname.lastname@example.org—equine staff veterinarian—California Department of Food and Agriculture Animal Health Branch, Sacramento, California
This is an excerpt from Equine Disease Quarterly, funded by underwriters at Lloyd’s, London.