Equine Infectious Disease Outbreak Response 101

Don't wait for a confirmed diagnosis to quarantine a horse if you suspect an infectious disease.

Photo: Thinkstock

From equine herpesvirus and influenza to strangles and coronavirus, infectious diseases can cause quite a stir in the horse industry—quarantines, canceled competitions, and, in some cases, even horse deaths or the threat of human infection. And something all horse owners and veterinarians should know is how to respond in the face of an infectious disease outbreak.

At the 2014 American College of Veterinary Internal Medicine Forum, held June 4-7 in Nashville, Tennessee, J. Scott Weese, DVM, DVSc, Dipl. ACVIM, gave attendees a run-down of some important steps to remember and take should an outbreak occur, regardless of what disease is at the center of the issue. Weese is a professor in the Department of Pathobiology and Centre for Public Health and Zoonoses at the University of Guelph's Ontario Veterinary College. 

Act early. "The earlier a problem is identified, the sooner a response can be initiated," Weese said. "This can help contain the disease, prevent spread on or between farms, obtain earlier diagnostic testing results, and foster effective communication." While it might be scary to tell your barn owner or your veterinarian that your horse has spiked a temperature and you think he might be contagious, it's in the best interest of your animal and others on the property to take action at the first sign of a problem.

Don't wait for a diagnosis. "Getting information about the scope of a problems is critical … but solid data confirming that an outbreak is actually present and its scope are not always required to initiate a response," Weese said. In many cases, he said, there are only a few disease culprits that could be responsible for an outbreak and the response can be tailored for the disease once a diagnosis is obtained. But, Weese said, "the core components of outbreak response are the same for most infectious diseases so an effective initial response can be developed while diagnostic testing is pursued."

Regardless of whether your horse contracted herpesvirus, influenza, or strangles, he'll need to be quarantined from other equids on the property. Don't wait for a diagnosis to move him to an isolated location.

But, get a diagnosis as soon as possible. "Making a definitive diagnosis can allow for refinement of the outbreak response to improve its effectiveness and potentially relax some measures that are no longer necessary," Weese said.

Gather a team. Managing an equine infectious disease outbreak is something best accomplished with a team of people who have different strengths, Weese said.

"Ideally, an investigation team contains individuals with expertise in the infectious disease or outbreak investigation, clinicians that are performing ground-level response and interacting with owners, and relevant stakeholders (such as owners, farm managers, or trainers)," he explained. But build your team carefully, Weese cautioned—ensure you choose individuals that can contribute to creating and maintaining a positive and productive environment and that relevant groups aren’t left out.

Ask for help. Simply put: There is no shame in asking for help from an experienced outside source when faced managing with an infectious disease outbreak (or any other scenario, for that matter).

"Consulting with equine infectious disease specialists, either remotely or integrating them as part of the outbreak team, is important and should be done early in the process," Weese said. "Recruitment of external experts is not an indication of an uncontrolled or uncontrollable outbreak or lack of competent local personnel; it is an understanding that there are people with additional expertise and experience in these rare situations," he stressed. "Ego should never get in the way of getting proper advice."

Additionally, Weese said, it's important for the attending veterinarian to keep local regulatory personnel informed of the situation, as they could be able to provide expertise, funding, or assistance in managing the outbreak.

Respond aggressively, then dial back. "It is much better to implement a comprehensive—and sometimes quite restrictive—set of measures at the start of an outbreak, with the removal of some over time, than to try a stepwise approach starting with a few measures and increasing them if (or when) they do not work," Weese said.

Not only could this approach mean the difference between a few and many horses being affected, it can also help make affected owners' lives easier—rather than more difficult—throughout the course of the outbreak.

Try to determine who, what, where, when, why, and how. While it might be easy to get wrapped up feeling sorry for yourself if your horse contracts an infectious disease, there might be other horses—sometimes scattered across the country—that could be affected as well. Therefore, Weese advised looking critically at:

  • Who: This can shed light on which individuals could require diagnostic testing and quarantine—essentially, the cohort of at-risk horses. For instance, if your horse said hello to several horses at a competition a few days before developing a fever and nasal discharge, the horses that came in contact with your horse would be considered at-risk and should be isolated and undergo diagnostic testing as soon as possible.
  • What: What disease does your horse have? It's important to know, so those caring for the whos can test for and take appropriate steps to protect other horses against the disease.
  • Where: "Where can involve multiple levels of investigation," Weese said. Is the outbreak confined to your farm, or has your horse travelled to a competition recently? Did you trailer your horse, or did a commercial transporter haul him—possibly along with several other horses that ultimately ended up at several different locations? Try to figure out where your horse was in the recent past, and alert the appropriate individuals to ensure possibly exposed horses receive proper care.
  • When: Do your best to determine when the pathogen entered your herd, as this can help modify the response and identify potentially exposed horses.
  • Why: Did the outbreak occur because a fellow competitor borrowed your water bucket and did not disinfect it after use? Or perhaps because you did not quarantine a new horse upon arrival at your facility? "In some situations, the why may indicate an ongoing gap or risk that needs to be addressed during the active outbreak response," Weese said.
  • How: Finally, try to determine how the pathogen was transmitted to your horse in the first place. "How can be taken in many ways, but perhaps the most important are how the pathogen has been transmitted, how it can be further transmitted, and how it can be contained," Weese said.

Don't overthink things. "Infection control isn't rocket science," Weese said. The keys to controlling infections disease are movement restrictions, isolation, barrier protection, and personal hygiene.

Have an official on the farm. "A ground-level presence of some team member is needed to understand the layout, confirm reported information, observe standard practices, monitor implementation of recommendations, identify infrastructure or management challenges, and to be able to talk directly with stakeholders," Weese said.

Don't shy away from communicating. True or false: One of the most frustrating things is knowing there's a case of an equine infectious disease in your county, or maybe even your town, but not being able to find any additional reliable information. True, right? So don't leave other horse owners out to dry should an infectious disease befall you. A few things to remember about your communications:

  • Truth is better than rumors. "Prompt and transparent communication is important, as it is much better for people to realize they will get timely and accurate information from the investigation team, rather than to rely on rumors," Weese said.
  • Don't announce a problem without a solution. Weese said this will help calm worried individuals and motivate them to help or comply with any required actions.
  • Update stakeholders regularly. "If communication slows down, fears and rumors can rise, or compliance can decrease if the need for ongoing practices is not emphasized," Weese said.

Empathize … appropriately. Before pointing fingers at a farm with a neurologic equine herpesvirus outbreak, consider that other horse owners could be dealing with the deaths or hospitalizations of their beloved horses. Or, consider that a racing stable could be losing their income if horses in their barn are quarantined and unable to race.

"It is important to recognize the hardship that people may face," Weese said.

But, don't allow your empathy to interfere with responding appropriately to an infectious disease.

Perform an outbreak post-mortem. While it might be easiest to try to forget about the struggle that is an equine infectious disease outbreak, it's always a good idea to conduct a so-called post-mortem to see what worked, what didn't, and what can be improved upon to prevent future disease outbreaks, Weese said.

Take-Home Message

"Early intervention, obtaining the input of relevant experts, applying basic infection control and epidemiologic tools, and effectively communicating are critical components that need to be applied to any investigation and response," Weese concluded.

About the Author

Erica Larson, News Editor

Erica Larson, news editor, holds a degree in journalism with an external specialty in equine science from Michigan State University in East Lansing. A Massachusetts native, she grew up in the saddle and has dabbled in a variety of disciplines including foxhunting, saddle seat, and mounted games. Currently, Erica competes in eventing with her OTTB, Dorado.

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