Horse show season is upon us, and with it comes the questions from concerned horse owners who want to protect their animals from the infectious diseases they may encounter at these events.  In this case, the specific question is:

What protocol would go into place if a horse with a highly contagious disease such as EHV-1 were to be found at a competition in Canada?

The short answer (to the surprise of many) is that there is no pre-established nation-wide protocol for most equine disease outbreaks.  Every outbreak is managed differently, based on the disease, the types of horses, where exposure might have occurred and a range of other factors. Typically, a disease like EHV isn’t going to be noted during the show, since it takes some time for illness to develop after exposure. Therefore, the response is more of an investigation of what happened at the show, why and how it can be prevented in the future, and of course trying to prevent further transmission in the community (e.g. identifying exposed horses, communicating with people who have been to the show with recommendations to quarantine and test exposed horses and potentially all horses, surveillance for ongoing transmission from horses that have left the show).

With horses, there’s no regulatory body with a mandate to oversee (and fund) this type of investigation unless it’s a federally reportable disease like rabies (and even then, assistance may not be forthcoming). Some provinces have more authority and interest (e.g. the Animal Health Act in Ontario gives the province a mandate and powers to intervene) but often investigation is not a priority for regulatory bodies and it’s left to whoever is around and interested. There are some good outbreak management guidelines from different institutions or groups (e.g. the ACVIM consensus statements on EHV and strangles) but there is no standard approach. Because testing costs are placed on the owners, responses can be quite variable since getting people to test when indicated can be a challenge. Additionally, getting people to follow quarantine recommendations is a challenge because of inability to effectively quarantine on their farm or unwillingness to do so (usually more the latter). So, each outbreak ends up being managed quite differently.

In general, the key points to outbreak investigation and management are:

  • Identification of a problem
  • Diagnosis of the problem
  • Communication to let people know what’s happening
  • Identify potentially exposed and infected horses
  • Quarantine, if appropriate (usually some form of quarantine is indicated, but not necessarily for all diseases)
  • Develop testing recommendations
  • Develop and communicate a plan to maximize compliance with quarantine and testing
  • Create a way to centralize data collection and communications, so that a clear picture of what is happening is obtained
  • Keep people in the loop as the investigation ensues to maximize compliance and decrease loss of compliance because of boredom or fatigue with the recommendations