Learn how disease outbreaks in recent years have changed the horse industry. And why it’s so important to play your part when it comes to disease prevention efforts.

In June of 2011 an outbreak of equine herpes virus (EHV) at a cutting event in Ogden, Utah, changed the horse world. By the time the outbreak was reined in, more than 2,000 horses and 242 premises were exposed in 19 states. Seventeen cases in California alone resulted in the cancellation of 142 of 520 competitions scheduled in the state. And social media panic in response to news reports caused events across the country to shut down even where risk of exposure was nonexistent. Industry experts quickly realized something needed to be done to change the way the horse world responds to the threat of disease.

So where did things go wrong? Let’s find out. Ogden taught us a lot about the spread of equine disease. And just how sideways things can go if we don’t pay attention. And since 2011 we’ve learned a lot. In this article, we’ll look at what went wrong in Ogden. As well as what we’ve learned since then, and what steps industry insiders have introduced to keep our horses safe. Most important, we’ll help you understand why there are so many regulations in place to control movement of horses and reduce spread of disease. And why it’s so important to comply with those (sometimes frustrating) rules.

Anatomy of an Outbreak

There are many different diseases that can lead to widespread outbreaks. Including both viruses, such as EHV and influenza, and bacteria, such as strangles. The list is long, and each disease has different characteristics including signs, severity, and mode of spread. Some hit fast and hard, with high rates of infection, while others strike more stealthily. But no matter what the underlying disease is, there are four factors that play into the creation and impact of an outbreak. These are, widespread travel, concentration of large numbers of horses in small spaces, lack of detection, and misinformation that leads to panic.

Widespread Travel

The scope of equine travel has shown staggering growth in recent years, both internationally and right here at home. In 1997, there were 517 international equine events recorded. This number increased to more than 3,400 by 2016. When horses travel, they bring diseases with them. While travel from faraway places to attend equine events isn’t likely to slow down any time soon, taking steps to reduce the risk that horses arriving at a facility aren’t carrying a disease can help reduce risk. Newer rules to address these challenges include:

• Requiring vaccinations against infectious diseases, such as EHV and influenza, at regular intervals for participation in an event. Even though all vaccinations aren’t 100% effective at preventing disease, most do decrease the amount of virus your horse will shed if he gets sick. Meaning they can help control spread.
• Requiring daily temperature logs from the days leading up to arrival at the event. Some competitions even require that your horse’s temperature be taken at the time of arrival. Even prior to your horse being allowed into the stabling area. Fever is often the first sign of an infectious disease. And can be detected before your horse shows any other symptoms. By identifying a fever before your horse is allowed into a venue where he’ll be exposed to other horses, the risk he’ll introduce an infectious disease is reduced.
• Requiring a statement of health from your veterinarian for entry to an event venue.

Large Groups of Horses

Large competition grounds mean huge numbers of horses commonly come together to compete. Which can set up a perfect storm for disease transmission. There were more than 400 horses at the show in Ogden, and the number of horses congregating at events has only gotten larger since. Approximately 700 horses were on the show grounds in Thermal, California, when a large-scale EHV outbreak hit in 2022. That’s a lot of horses sharing space. Not only are they close together, but these horses that are traveling, competing, and living away from home are likely to be stressed. Meaning their immune systems aren’t quite as good at fighting off disease.

Some of the recently introduced risk reduction strategies include:

• Discouraging nose-to-nose contact of horses. Event venues should provide large enough warm-up and back-gate areas to allow horses space. Avoid standing around with a big group of horses where the potential for exposure is especially high.
• Discouraging the use of shared water sources. Whereas many events used to offer larger troughs for horses on the property, this no longer happens. If you do need to offer your horse a drink at the warm-up arena, bring your own bucket along.
• Discouraging sharing of grooming supplies or tack. Even if you are traveling with a group of horses, it’s best if each horse has its own equipment. That way if one horse in the group is exposed to a disease-causing organism, it’s less likely it will spread to others in the barn.
• Requiring “lights out” hours overnight to allow horses time to get restorative sleep. And research tells us this is essential for a strong immune system. Many governing bodies controlling equestrian sports now require a specified amount of time during the night where lights are dimmed and activity is curtailed so horses won’t
  be disturbed.

Slow Detection and Tracking

Many of the horses at the Ogden outbreak made it back to their home barns before the first case was identified. That made it almost impossible to control the spread. Remember that horses often spike a fever before showing any other signs of disease. And the more efficiently we can identify horses that may have been exposed, the better our chances for avoiding a large-scale outbreak. Strategies to help detect a disease and trace its spread so that we can stop it in its tracks include:

• Requiring daily temperature logs during an event for horses housed in a large facility. Identifying a fever immediately means a horse can be moved out away from other horses, reducing risk of disease spread.
• Provision of isolation facilities and isolation protocols by event managers in case any sign of disease is detected. Most events are now required to have a designated stable where horses can be isolated. As well as protocols require that any horse identified to have a fever or other sign of an infectious disease (such as a snotty nose or diarrhea) be isolated immediately.
• Adhering to regulations for Certificates of Veterinary Inspection (CVIs or health certificates) that provide information needed by authorities to track horse movement. Traceability of disease depends on three factors: identification, location, and time. An official veterinary inspection helps locate individual horses by placing them at a known location at a specific point in time. With this as a starting point, officials can identify horses potentially exposed to an outbreak as quickly as possible for the purposes of quarantine and preventing spread. If you don’t have a CVI, officials won’t be able to warn you if they discover your horse has been exposed.

Misinformation and Panic

It never fails. The minute a whisper about a potential outbreak hits the horse world, the panic starts. In Ogden, this meant cancellation of events in locations far removed from any risk, resulting in significant (and unnecessary) impacts on the entire U.S. horse industry. And in the Thermal outbreak, owners first hearing reports of the disease being identified on the property panicked, packed up, and headed for home—taking the virus with them. This behavior resulted in spread to other facilities that could have been avoided. And horses died as a result. Strategies to avoid panic require improved communication. These include:

• Reporting any infectious disease that’s on your farm or at an event to appropriate authorities immediately. Most states have a list of “reportable diseases” that horse owners and veterinarians are required to report to authorities when diagnosed. This allows for monitoring and enforcement of isolation protocols. You may not want to let people know that you have a disease at your facility. But keeping things a secret will only increase the chance of spread.
• Complying with isolation requirements and avoiding taking a horse out of any situation where there was potential for exposure to reduce the chance of spread. Even if your horse isn’t showing any signs, you should stay put if you are at a facility where an infectious disease has been identified.
• Seeking accurate information about potential outbreaks. If your vet or the facility can’t give you the answers you are looking for, check the Equine Disease Communication Center website (equinediseasecc.org) or visit HorseandRider.com and head over to our EDCC Health Watch page. This website was designed by industry leaders in response to Ogden and is a valuable tool that’s packed with information and usually up-to-date about new or ongoing outbreaks across the United States.

Playing Your Part: Dos and Don’ts

There’s no doubt about it. Rules can be annoying. And it seems like new rules are popping up every day. It helps to realize that many of these new rules are the direct result of what we’ve learned about disease outbreaks in recent years. And they are designed both to help minimize risk to individual horses and the potential impact of an outbreak on the horse industry as a whole. You may not like taking your horse’s temperature every day or being restricted from the horse show barn in the middle of the night. But in most cases the inconvenience is worth the protection it affords. And it’s especially important that everybody does their part. It only takes one sick horse to start an outbreak. Make sure that one horse isn’t yours by adhering to the following dos and don’ts.

Be Prepared!

Do: Schedule your veterinarian for a CVI before embarking on any travel with your horse.

Do: Make sure your horse is currently vaccinated against diseases such as influenza or EHV if you’ll be traveling.

Don’t: Travel with your horse that has spiked a fever or developed other signs (such as a snotty nose, cough, or diarrhea) of a potentially transmissible disease. Even if you do have papers!

Don’t: Fudge your temperature logs. It might be annoying to have to take your horse’s temperature every day. But it’s one of the most important steps to prevent outbreaks.

Do: Report to event or facility managers if your horse spikes a fever at any time, and comply with requested isolation protocols.

Don’t: Allow your horse to drink from any communal water sources.

Don’t: Share grooming equipment or tack, especially with unfamiliar horses.

Do: Seek accurate information if you hear whispers about a potential outbreak before you make a move. Talk to your vet or facility managers to find out what’s recommended.

Be Smart!

Don’t: Take your horse home or to another barn if he’s been exposed to an infectious disease. Even if he isn’t showing any signs.

Don’t: Fuel the fire by spreading information that hasn’t been confirmed. This includes information you obtained through social media or barn-aisle conversations.

Do: Check out the EDCC website and remember this important resource if you are looking for information about an outbreak.

Do: Consider establishing an isolation protocol at your home barn for new horses being introduced. Or for horses returning from events.

Don’t: Complain about the rules! Try to remember that every requirement and every new rule has been put in place to help protect you and your horse.

With widespread travel of horses and the increasing popularity of large event venues, risks of disease outbreaks are here to stay. If we all play our part, we can reduce the risk of those outbreaks spiraling out of control. That’s the only way to keep our horses safe.