Written by: Teresa Pitman

Understanding how horses contact one another in a show environment leads to an improved understanding of disease prevention.

Thumbnail for Fighting Horse Show Epidemics

Pam MacKenzie Photo

The horse world has already seen how an infectious disease can spread quickly in a horse show environment. It started in the spring of 2011, when the National Cutting Horse Association Western Championship event was held in Utah, involving more than 400 horses. At least one of those horses was apparently infected with Equine Herpes Virus-1 (EHV-1), a serious contagious disease which can cause neurological damage or death. The virus is primarily spread as a result of direct contact between an infected horse and a non-infected horse.

For many infectious diseases there is a period of time during which the horse can be infectious to others, but not yet showing signs of illness. Therefore, newly-infected horses may not be identified as sick until they have returned to their home farms. In the absence of strong biosecurity, other horses at their home farms could be at risk of being infected as well. Some horses from the show didn’t go home immediately, but instead traveled to other horse shows, contacting more of their fellow competitors.

Over the next few months, the United States Department of Agriculture reported nearly 100 horses in 10 different states whose infection with EHV-1 could be traced back to the championship horse show. Neurological disease was confirmed in 33 horses, and 13 horses died or had to be euthanized.

A dramatic and tragic situation, but University of Guelph veterinary student Kelsey Spence will tell you that although the risk of an epidemic is low, the potential exists at most horse shows. “Horses in competition are regularly in contact with many unfamiliar horses,” she says. “That means there is the potential for spreading disease.”

One Infects Hundreds

Under the supervision of Dr. Amy Greer, Spence conducted a survey at a two-day silver level dressage show in Ontario to determine how many contacts each horse might have. Most of the 55 horses she was able to gather information about were stabled overnight at the show facility. Owners were also asked to report the number of horses housed at their home farm. Participating horses came from 38 different home farms housing over 700 horses who were not participating in the dressage show. By tracking the information about contacts both at the show, and back at the farm, Spence determined that if a single horse was infected with a contagious disease at the show, there would be the potential to spread the disease to 779 other horses. There’s also the potential to spread any infections over a significant distance: some of the horses Spence tracked had traveled more than 370 km. to attend the show.

Not all contacts are created equally. Spence was interested in the different types of contact that could potentially spread diseases in a show environment. Based on the owners’ reports, Spence found that about 20% of the horses had direct contact with other horses while stabled at the show, about 40% shared cleaning tools, and 50% shared the washrack. However, only a small percentage shared equipment, water buckets or feed buckets. Spence also found that owners were more likely to engage in behaviours that minimized contact when away from their home farm.

This preliminary study captured only a snapshot of contacts associated with a single show and by tracking the information about contacts both at the show, and back at the farm, Spence determined that a single horse infected with a contagious disease at the show would have the opportunity to spread the disease to 779 others.

“That doesn’t include horses who continue to travel to other shows,” Spence adds. “We found that some owners were planning to travel to more than 30 competitions or activities with their horse over the next six months.”

Based on this initial study, Spence is planning to expand her research during the summer of 2015 to follow a group of horses throughout the showing season (May to November) to collect information about how often horses travel. This will give them more complete data about how horses in Ontario come into contact with one another.

BIOSECURITY = PROTECTION

Given the potential for disease spread, what can horse owners do? Ontario Veterinary College professor and veterinarian Dr. Scott Weese says you don’t have to lock your horse in the barn and never attend another show. You can reduce the risk if you follow some of his suggestions:

Before the Show

  • Make sure your horse has the recommended vaccinations. Talk to your vet about where you plan to travel during the show season, as that may change which vaccinations he or she recommends. This is especially true if you are travelling to other provinces or outside Canada.
  • Ensure your horse is fit before the show season starts. For example, if he is underweight or has some digestive problems, you may need to make adjustments to his feed. A fit and healthy horse has better resistance to disease even if he is exposed to some contagious illness.
  • Don’t take your horse to the show if he has any signs of illness such as fever, lethargy, discharge from his nostrils, etc. If he is already sick he is at greater risk of catching any other disease he might be exposed to. Of course, the bigger concern is that he might spread the disease to other animals at the show.
  • When you register for the show, asking about stabling options. Many show organizers will stable horses from a particular farm next to each other, reducing the risk of contact with an unknown horse. Another option might be to stable your horse next to others he regularly trains with.
  • Plan to bring all the food, water buckets, and other equipment you might need from home. It’s preferable to have a separate set of brushes and other cleaning tools for each horse. Then if only one of your horses is exposed to an infectious disease, it is less likely to be transferred to the others.

During the Show

  • Try to keep your horse from having direct contact with other horses. This is often an issue with junior riders who may visit and talk to their friends while sitting on or leading their horses, and not notice that the horses are touching noses.
  • Avoid sharing water buckets, tack or other equipment. If you are going to use a wash rack that has been used by other horses, run the water for a few minutes to clean the area before taking your horse in.
  • People can also transmit disease between horses. Have you ever watched visitors at the horse show barn walking from stall to stall, patting each horse on the nose and then moving straight on to the next horse? That’s an easy way to spread germs. One way to keep visitors back is to set up lawn chairs or perhaps a table or trunk in front of the stall doors, making the horses more difficult to access. You might also put up signs asking visitors not to touch or pet the horses, but these are often ignored.

When you Return Home

  • Once you get home, treat your horses as though they might have been infected. If at all possible, keep the ones who went to the show separate from the others. This is especially important if you have pregnant mares, as some infections that can be mild in other horses may cause miscarriage in the pregnant mare.
  • Watch the show horses carefully for signs of illness over the next few weeks. If you are working with one of your show horses, wash your hands thoroughly before going to work with another horse.
    “A lot of this is common sense, but we don’t always remember to do it,” says Weese. “Following through on the basic steps before, during and after the show will reduce everyone’s risk.”