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The Rundown: Strike a Balance Between Showing and EHV-1

Competitors can strike a balance between protecting their horses and continuing to travel the show circuit.

By Tara Christiansen
The American Quarter Horse Journal
May 20, 2011

Before departing for a show, provide horses you think are at risk with an immunomodulator to stimulate their immune systems. Journal photo.

In light of the current equine herpesvirus-1 myeloencephalopathy outbreak, many associations have cancelled or postponed horse shows or enacted contingency plans. As a result, horse owners are having to make the difficult decision between continuing their passion and livelihood of showing horses or putting it on hold to stay at home for the welfare of their horses and the equine population.

According to Dr. Tom Lenz, past president of the American Association of Equine Practitioners and a regular columnist in The American Quarter Horse Journal, competitors can strike a balance between protecting their horses and continuing to travel the show circuit.

“When traveling with our horses, (be) aware of the potential for exposure to infectious agents and taking daily steps to minimize that exposure,” Dr. Lenz says. “Good vaccination programs and biosecurity should be practiced on a continual basis and will prevent most outbreaks like we are experiencing now.”

That said, Dr. Lenz notes that there is no breed or discipline predilection when it comes to the EHV-1 outbreak.

“The current EHM outbreak started at a cutting horse show, but all horses are susceptible to this disease or any infectious diseases. The last major EHM outbreak occurred in hunter-jumper and event horses in the eastern part of the country. Viruses like equine herpesvirus and equine influenza are a potential threat any time large numbers of horses are brought together in close proximity, such as horse shows, trail rides, etc.”

The current EHV-1 outbreak is in the western United States and Canada, but in the past, outbreaks have occurred across the entire country, he says.  

The facts:

  • EHM is caused by equine herpesvirus type 1 (EHV-1), which causes upper respiratory infections, abortions and, on rare occasions, neurological disease (EHM). 
  • EHV-4 primarily causes respiratory disease.
  • The incubation period (time from exposure to becoming ill) is one to two days, with clinical signs of fever, depression, nasal discharge and loss of appetite.
  • If the neurological form of the disease occurs, it usually does so within eight to 12 days, with clinical signs of weakness, lethargy, urine dribbling, decreased tail tone and inability to stand.
  • In addition to EHV, the most likely other upper respiratory infective agent is equine influenza virus, which will also cause an elevated temperature, depression and nasal discharge, but will not progress to EHM. 
  • Respiratory viruses are transmitted through both direct and indirect contact with infected horses and can be spread via contaminated water buckets, feed tubs, tack, grooming equipment and even on the hands and feet of people.

If you decide to travel and compete in the next several weeks, Dr. Lenz suggests taking certain measures before you depart.

“Ask your local veterinarian to check the entry requirements for states you may be traveling to or through. Some may have new restrictions or requirements for blood tests or body temperature readings,” he says. “It’s important that your horses are vaccinated against these viruses at least two to three weeks or more prior to the trip.”

Whether you’re at home, on the road or you’ve reached your final destination, particular attention should be given to cleaning and disinfecting stalls and equipment periodically to prevent exposure. Since manure and dirt can make bleach-based disinfectants ineffective, Dr. Lenz suggests the use of Nolvasan or Roccal-D.

According to Dr. Lenz, there are several actions that will decrease the chances of your horse contracting EHV-1:

  • Isolate sick horses or new arrivals on your premises for at least 21 days to ensure that they are not infected.
  • Check your horse’s temperature each morning, as most respiratory infections, especially EHM, are preceded by an elevated body temperature (102.5 degrees F or more). Remember, the normal temperature for an adult horse is 100.5 degrees F (101.5 degrees F for foals).
  • If one of your horses becomes sick, isolate it immediately.
  • Booster your horses with EHV-1, EHV-4 and EIV vaccines.   
  • Before departing for a show, provide horses you think are at risk with an immunomodulator to stimulate their immune systems.
  • Don’t share equipment and limit your horse’s exposure to other horses and disease vectors like mosquitoes or flies. 
  • While traveling or at the show, avoid nose-to-nose contact with other horses and do not water your horses at communal water tanks.
  • Keep Coggins papers and health certificates up to date. 
  • Work with your local veterinarian to develop a good vaccination and preventive medicine plan.
  • Most importantly, make biosecurity a habit at home and on the road. 

If you believe that your horse has been exposed to EHV-1, Dr. Lenz says not to panic.

“Although many exposed horses may come down with an elevated temperature, runny nose, depression and no interest in eating, only a very, very small percentage will actually develop the neurological form of disease. And most of them will be either very young horses (less than 1 year of age) or old horses that have poorer immune systems.

“If clinically ill horses are identified and isolated, preventing new cases, I expect that the outbreak will be over in a few weeks. At least that’s been the experience with earlier outbreaks of EHM.”

Keep in mind that while EHV-1 and EHM should be treated with the utmost caution, it’s safe herd management practices that can rein in the EHV-1 outbreak.