Lessons From a Horse Show Disease Outbreak

Discover how one horse show venue handled a disease outbreak and improved its biosecurity practices to prevent one in the future.
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Using basic biosecurity practices at horse shows can help keep your horse and others safe. | TH Staff

Show horses are often at risk of contracting diseases due to the increased stress associated with showing and exposure to new horses and environments. Basic biosecurity practices can often help prevent a multitude of contagious diseases, especially at large horse show venues, but in some cases, these practices are not implemented until after an outbreak occurs.

“Biosecurity refers to selected measures aimed at preventing the introduction and/or spread of harmful organisms intentionally or unintentionally,” says Nicola Pusterla, DVM, PhD, Dipl. ACVIM, professor of equine internal medicine at the University of California, Davis, School of Veterinary Medicine.

The Equine Disease Communications Center reports numerous disease outbreaks every year, along with many sporadic cases of equine herpesvirus-1 (EHV-1) and equine herpesvirus myeloencephalopathy (EHM) affecting small numbers of horses at a time.

When going to a show or event, be sure to follow the facility or governing organization’s biosecurity and vaccine guidelines. Ideally, every event and facility has unique biosecurity protocols, which can help safeguard your horse’s health, but do not rely fully on the facility to protect your horse—take matters into your own hands and learn more about biosecurity measures you can implement yourself, says Pusterla.

Managing a Disease Outbreak at a Horse Show

In 2022 Pusterla and his team partnered with Steven Hankin, president and chief executive officer of Desert International Horse Park (DIHP), located in Thermal, California in response to a disease outbreak and to develop continued prevention methods.

“We have 2,600 stalls on 239 acres, and in an average week we have 2,000 horses on the property,” says Hankin. “We’re proud to be the only horse park in the U.S. with a dedicated biosecurity veterinarian.” But this was not always the case. Until an EHV-1 outbreak at DIHP three years ago, biosecurity was not a topic Hankin and his team discussed.

“Then (a disease outbreak) hit,” says Hankin. “We initially had three cases, two of which were EHM, which quickly spread to a total of 21 horses on the property. The affected horses had to be quarantined for five weeks to protect the other horses on the show grounds and at their home farms.

“I wanted to learn how to reduce the probability and severity of another outbreak, and what we found was all the documents on biosecurity were all outdated,” says Hankin. “So, I made a commitment to advance the practice and science behind biosecurity. DIHP has enjoyed a three-year relationship with UC Davis. We’ve worked hard on our protocols and thankfully haven’t had an outbreak since then.”

Lessons Learned From an Equine Disease Outbreak

“We (now) prevent sick horses from coming to the park,” says Hankin. “We have standards for horses coming on the property, requiring a state certificate of veterinary inspection and an owner/trainer statement attesting to the health of the horse.” While this system is not perfect, it has created awareness among horse owners and trainers regarding biosecurity practices and disease prevention, he adds.

“We also have a staff veterinarian who has created relationships with veterinarians in the community, and they discuss diseases seen in the community to keep the horses at DIHP safe,” says Hankin. “Nothing is ever 100% perfect, which is why it’s important to keep the dialogue going.” Hankin and his team also require owners, trainers, or handlers to take temperatures of all horses on the premises twice daily.

Because of his experience with EHV-1, Hankin’s team set up pre-isolation and isolation areas. They also established stringent testing protocols for disease. For example, if a horse tests negative for contagious diseases but still has a fever, the horse remains in pre-isolation and veterinarians retest him five days later.

“This is a different approach than what we’ve done before and is a good example of how our protocols are advancing,” says Hankin. “Nowhere is it written that a percent of cases will get a negative on the first test but positive on the second. To expedite things, we have an onsite point-of-care PCR (polymerase chain reaction test) provided by Fluxergy to test for EHV-1 that we back up with testing at UC Davis.”

Once a horse in pre-isolation tests positive, he’s moved to isolation within hours to try to minimize impact on the remaining horses on the property. “We also swab every stall four times a season testing for EHV-1, and that gives us insight into frequency of undetected shedding,” he adds.

Spreading Positive Biosecurity Awareness

Hankin says biosecurity constantly stays on his and his team’s minds. “Going through that EHV-1 outbreak was probably the most difficult thing I’ve gone through in my life,” he says. “When there are 2,000 horses on the property, including your own, it’s horrible. It’s personal.”

Contributing to the challenges of managing an outbreak was social media. Hankin says that too many people with social media behaved as experts, and everyone seemed to have an opinion on handling the outbreak but had few or no facts.

“Social media often creates panic, which clouds the judgment of many people,” says Pusterla. “The key to properly managing an outbreak is not to search for answers on social media but to listen to the organizers, veterinarians, and professionals that manage the event and take an active role in outbreak mitigation. Too often we see horse owners fleeing an event dealing with an outbreak like fugitives, to only carry the culprit pathogen back to their own barn and spreading it to resident horses. This observation has repeated itself again and again and was responsible for the multicounty outbreak (in California) of EHM in 2022.”

Take-Home Message

Given the severe consequences of an infectious disease outbreak at equine events, Hankin continues to ask, “Why aren’t people demanding more biosecurity protocols?”

He feels that many owners lack general knowledge surrounding biosecurity principles. “You can go to most any barn at a horse show and watch someone walk down the aisle touching all the horses because they love horses,” says Hankin. “It’s these behaviors that directly contribute to disease transmission that can result in devastating outbreaks from a simple lack of reliable knowledge.”

Before traveling with your horse, refresh your knowledge on the facility and governing organization’s biosecurity rules and catch disease before it spreads by monitoring your horse frequently and alerting horse show management to any changes in his health.


Written by:

Stacey Oke, MSc, DVM, is a practicing veterinarian and freelance medical writer and editor. She is interested in both large and small animals, as well as complementary and alternative medicine. Since 2005, she’s worked as a research consultant for nutritional supplement companies, assisted physicians and veterinarians in publishing research articles and textbooks, and written for a number of educational magazines and websites.

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