A Vet’s View: Protecting against equine herpesvirus 1

January 13, 2017

The horse industry has once again been confronted with a high profile quarantine caused by neuropathogenic equine herpesvirus 1 (EHV-1). This frightening and frequently deadly disease is caused by a virus that normally causes respiratory disease or abortion. A mutation of the disease, however, can cause neurologic disease in horses that results in weakness, incoordination, inability to stand, high fever and sometimes death.

Premises with infected horses are quarantined by state officials, which can restrict the shipping any horses out of the facility for extended periods of time. Quarantines for this disease have affected nearly every breed and discipline in the U.S. horse industry and can last for months. The devastation, both financial and emotional, of neuropathogenic herpesvirus on your farm is long-lasting and extensive, making it clear that preventing this disease from rearing its ugly is vitally important for all horse owners.

Given the lack of any vaccine protection for neuropathogenic herpesvirus, prevention is only possible through effective biosecurity. Biosecurity is one of those words that conjures images of government officials in respirator masks swooping in to cordon a farm, but in reality, biosecurity is something we all already practice in one form or another.

For example, you already wash your hands and clean stalls regularly —both practices of basic biosecurity. With some careful consideration and little effort, effective biosecurity can help protect your horse from exposure to devastating diseases like EHV-1. In essence, the goal of biosecurity is to keep your horse healthy by not exposing them to disease in the first place.

The first step horse owners need to consider is preventing disease from entering into their barn. This means limiting access to visitors, both equine and human. Human visitors should have clean boots or shoes and wash their hands prior to any contact with the animals.

Horse visitors are an entirely different concern. A great first step is to require current health papers for each visiting horse, but this certainly cannot guarantee only healthy horses will arrive. Horses shedding herpesvirus may not be showing clinical signs of disease, so you need to consider every horse coming onto your property as potentially dangerous.

Isolation of animals entering your facility is imperative, whether it’s a new horse or a horse returning from a show. Taking the temperatures of those horses daily (or twice, if possible) for a minimum of two weeks before returning them to the main facility, will help keep your facility safe. If horses have been exposed to known or suspected cases of EHV-1, your veterinarian can use diagnostics to identify shedding animals. Of course, any horse showing signs of disease requires an immediate call to your veterinarian.

Beyond isolation and limiting admission of new or returning animals to the farm, it’s important to consider appropriate cleaning and disinfection of equipment and tack. Cleaning is one of the most important steps in disinfection and should be done with a quality soap or detergent. Removal of organic material should always be done prior to disinfection for the best results.

Disinfectants come in many varieties, so it is important to look for a safe, effective product that will not damage any of your tack or equipment. Always use disinfectants per label instructions and dilutions, as mixing a more concentrated solution than recommended can actually decrease the effectiveness of some disinfectants. Contact times are also listed on labels and should always be followed. For example, a disinfectant listed as needing 10 minutes of contact time must truly be left on for 10 minutes.

Finally, cleaning and disinfecting your facility and trailer should be performed on a routine schedule and after any suspect horses have occupied them. Many people reach for the pressure washer when cleaning stall surfaces, but these can cause disease containing particles to disperse in the air and spread around the facility. Instead, use a foaming cleaner applied with a hand sprayer before scrubbing the surfaces, followed by a full rinse according to label directions.

Next, apply the disinfectant with a sprayer or mop, being careful not to contaminate the solution with the cleaning tool. Barns and trailers present a difficult challenge for disinfection due to porous surfaces and the amount of organic material normally present. Make sure to thoroughly apply the product and rinse as recommended. Keep in mind that the best intentions may be undone by accidentally carrying pathogens from a dirty area to one already cleaned. If you stand in a dirty aisle the entire time you spray your stalls and then walk back into a previously cleaned area, you will have lost any of benefits of your cleaning. Think systematically to make sure do not decontaminate previously cleaned or disinfected areas or equipment.

Thankfully, herpresvirus is generally not resistant to proper disinfection. Good environmental hygiene and a sound disinfection program, combined with a rational approach to horse and human traffic in your facility, should provide a strong level of protection for your animals. Remember that, like many diseases, you can’t always see a herpesvirus shedding horse. Assume that any horse that enters your facility is a potential risk and act accordingly. This doesn’t have to rise to the level of paranoia, but by remembering that apparently healthy horses can still harbor disease, this may prevent you from being the next story on the news.

This blog was written by Neogen’s professional services veterinarian, Dr. Joe Lyman (pictured top left). For more information on Neogen’s animal safety division, including our full line of biosecurity and equine products, see our website.