Controlling Contagious Equine Diseases

When an EHV-1 outbreak or other contagious equine disease strikes a community, here's how to respond to the crisis and reduce the risk to your horse.

EHV Outbreak.
Horses Euthanatized.
Farms Quarantined.
Travel Restricted.
Shows Cancelled.

Confining sick horses in a quarantine stall protects the health of his barnmates.

Headlines like these will catch any horse owner’s attention—usually, we all hope, with a sigh of?relief that the outbreak is somewhere far away.

But that’s not always the case. Outbreaks of EHV-1, which may involve a potentially fatal strain of the equine herpesvirus that can produce neurological impairment, are not uncommon. The virus might crop up on one farm or a small cluster of farms somewhere in the country every year. Under the right circumstances, however, the outbreak can become widespread. When the disease appeared at the National Cutting Horse Association’s Western National Championships in Ogden, Utah, in the spring of 2011, each one of the 400 horses in attendance had some risk of exposure—and the threat wasn’t identified until all had returned to farms and ranches across 19 Western states.

For weeks that May, a number of shows and events were cancelled, and several barns and state veterinary hospitals were put under quarantine as new outbreaks cropped up in state after state from Washington to New Mexico. By the time the USDA-APHIS (United States Department of Agriculture’s Animal and Plant Health Inspection Service) declared the virus “contained” in late June, 33 cases of myeloencephalopathy caused by EHV infection had been confirmed in 10 states; 26 of those horses had attended the event in Ogden, Utah, and 13 died or were put down.

Yet officials say the 2011 EHV outbreak could have been far worse. Prompt action on the part of state and local animal health officials, veterinarians, event organizers and—most important—horse owners helped halt the spread of the virus.

If EHV or another contagious equine disease broke out near your property, would you know what to do? By establishing a plan now, and having a few basic materials and supplies on hand, you could not only protect the lives of your own horses, you could help prevent the next outbreak from growing into an epidemic.? A good biosecurity program need not be difficult or complex. In fact, your normal management practices are probably already covering most of the bases. Still, it’s a good idea to review your routines periodically just to make sure you’re not leaving any gaps, and to make plans for what you’d do in the event of a real emergency. Your veterinarian will help you tailor a program to your individual needs. Here’s where you can start.

Keep vaccinations up to date
Vaccination is an inexpensive but effective way to prevent your horse from contracting several serious diseases. The American Association of Equine Practitioners (AAEP) recommends that all horses receive vaccines against a “core” group of diseases: tetanus, eastern/western equine encephalomyelitis, West Nile virus and rabies. An additional eight vaccines are available for horses at risk of encountering diseases such as Potomac horse fever, strangles or EHV.

Which of these risk-based vaccinations a horse needs depends on several factors, including his geographic location, age and activities. Those who are frequently transported to horse shows, for example, require more protection than most “homebodies,” and the needs of a pregnant mare are different from those of a retired gelding.

Your veterinarian is your best resource for creating a vaccination protocol tailored to your horse. Especially if you’ve made any significant management or lifestyle changes in recent years, ask her to review your routine to make sure you’re still providing the appropriate protection for your horse.

Practice good daily hygiene
A number of diseases—including rhinopneumonitis, strangles and equine influenza—can be passed from horse to horse on human hands and with shared tack and equipment. Here are several tips for reducing the chances that you’ll inadvertently spread an illness around your barn:

  • Wash your hands after handling each horse. Cleansing your hands is one of the simplest yet most effective ways to avoid spreading infections. Develop the habit of washing with soap regularly, and consider installing wall-mounted dispensers of hand sanitizer between stalls or in other strategic locations. If your barn receives visitors, post signs to discourage the practice of going from stall to stall to pet each horse in turn.
  • Scrub water buckets and automatic waterers regularly. Keep one dedicated brush for each bucket. Also, never let the end of the hose touch the surface of the water as you fill the bucket.
  • Keep equipment separate. Ideally, each horse will have his own dedicated grooming brushes, blankets and sheets, bits and other items. Colored duct tape is a good way to mark each item to help avoid mix-ups—assign each horse his own color and use it to “tag” all of his equipment. Also, avoid sharing items with strange horses at shows or other events.
  • Disinfect equipment periodically. Practically everything that touches your horse picks up bacteria and other pathogens as well as dirt and grime. Machine washables, such as towels, blankets and saddle pads, can be disinfected in regular laundry cycles, but some higher end washers now feature sanitization cycles, which use steam or extra high heat to kill even more bacteria. Buckets, hoof picks and other impermeable objects can be disinfected with soapy water, bleach or other commercial cleaners (see “How To: Disinfect Buckets, Brushes and Other Tools,” opposite). Sponges are difficult to disinfect. Discard and replace them whenever they get dirty.
  • Control rodents. Rats can carry several diseases that affect both horses and people. Keep grain bins sealed, and promptly clean up any feed spills to deter vermin. Barn owls, cats and other predators will help keep populations down.
  • Manage manure responsibly. Some pathogens may be passed via contact with manure. Pick up wastes daily, and avoid tracking it around with your boots or wheelbarrow wheels. If you are caring for a sick horse, place a disinfectant footbath at your barn entrance. To make one, place AstroTurf or a textured welcome mat in a shallow basin and cover it with a 10 percent chlorine bleach solution. Then, step into it to scrub the organic material off the bottom of your boots as you enter and exit the barn, changing the footbath water as it becomes dirty.

Quarantine new or sick horses
A number of contagious diseases can be spread directly from horse to horse. “Modes of transmission include direct contact, inhalation, oral [ingestion], via open wounds or bites and venereal contact,” says Roberta M. Dwyer, DVM, professor at Maxwell H. Gluck Equine Research Center.

If you have a stable herd—a group of horses who live together and travel infrequently—chances are you’ll need to implement quarantine measures under only two circumstances: when you actually have a sick horse, and when you introduce a new horse.

Horses exposed to a number of common equine diseases may show no signs for a week or more, yet they are capable of passing the pathogens on to others. For example, a horse can easily be exposed to strangles or rhinopneumonitis at an auction, then carry the disease to the herd at his new home.

“New horses should be quarantined for at least two weeks prior to joining the herd,” says Dwyer. “Two weeks covers the incubation period for many equine infectious diseases, like influenza.” If the horse has a vague history or you’re unsure about his vaccination status, it’s wise to extend the isolation period to at least 21 days.

“New horses should have their temperatures taken twice daily for early detection of disease,” says Dwyer. Call your veterinarian at the first sign of fever. It’s also a good idea to monitor the temperatures of your resident horses during this time.

Another risk occurs when you have some horses who always stay at home but share space with others who do go to shows. The traveler could easily pick up an illness and spread it to the rest of the herd before you know he’s sick.

Have an action plan ready
To avoid wasting time in the event of a disease outbreak, establish an action plan. Keep on hand equipment and products that are necessary to clean and disinfect stalls, including plastic booties, gloves and protective coveralls. Consider how you would manage the practical aspects of isolating one or more members of your herd, and make sure you have ready access to your horse’s veterinary records, particularly his vaccination history.

Once you’ve developed a plan for dealing with sick horses, make sure everyone else who has access to your farm or works in your barn knows the procedures, too. Either meet with individuals informally or schedule a training session so that everyone knows how to recognize the first signs of illness and what to do if they spot something.

If an outbreak occurs in your area, get your information from reliable sources. Be wary of social media: When people panic, rumors run rife. Instead, rely on your veterinarian, your state veterinarian’s office or your state’s department of agriculture for updates. Sources like these will have websites with pages dedicated to news releases and alerts. Find the sites likely to cover your area, and bookmark them in a dedicated folder so you’ll be able to find them quickly in an emergency. Don’t forget to include the United States Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) at

Keep in mind that, even if a disease outbreak in your region does not affect your farm directly, equine transport may be restricted. You’ll find updates and bulletins on the state or federal websites.

Last year’s EHV-1 outbreak is behind us. It was contained in part due to the efforts of the National Cutting Horse Association’s quick response in spreading the word and voluntarily canceling events. But the countless individual owners, who heeded the warnings and kept their horses home, helped prevent a handful of cases from growing into a widespread epidemic.

Given the nature of this virus as well as other contagious diseases, similar outbreaks are certain to happen again. While you can’t guarantee your horse will never get sick, you can take steps to minimize his risks and the threat of the illness spreading. And that will benefit not just the residents of your own barn, but also the welfare of horses all around your state.




Related Posts

Gray horse head in profile on EQ Extra 89 cover
What we’ve learned about PPID
Do right by your retired horse
Tame your horse’s anxiety
COVER EQ_EXTRA-VOL86 Winter Care_fnl_Page_1
Get ready for winter!


"*" indicates required fields


Additional Offers

Additional Offers
This field is for validation purposes and should be left unchanged.