Recent, serious outbreaks of highly infectious and potentially fatal equine neurologic herpesvirus (equine herpesvirus myeloencephalitis, or EHM) continue to pop up throughout the country. Because of that, biosecurity is to be taken seriously. Any time horses congregate, they are subject to exposure to any number of infectious diseases. Other contagious concerns include strangles (Streptococcus equi), equine influenza, respiratory problems from equine rhinopneumonitis, vesicular stomatitis, and salmonella, to name a few.
There are effective equine vaccines against two viral respiratory diseases— equine rhinopneumonitis and influenza. Vaccination is one method of helping to contain the spread of those diseases. In fact, the United States Equestrian Federation (USEF) requires documentation of immunization against influenza and rhinopneumonitis twice annually in order to attend USEF events. The Federation Equestrian International (FEI) requires documented annual influenza vaccination.
Besides vaccinations, there are many other methods to maximize biosecurity and to keep your horses as safe and as healthy as possible.
On the Farm
To begin, let’s look at ways you can keep your horses safe from infectious disease at home. This starts by considering isolation techniques for new horses, as well as for those from the farm that travel in and out to clinics and events.
Keeping tabs on every horse on the property is sound advice. Know what is normal for each individual, and have barn personnel inform you if anything is amiss with a horse’s attitude, appetite, or manure and urine output. Any time something seems out of the ordinary, take a rectal temperature as a starting point. Temperatures exceeding 101 degrees F, especially in a horse that isn’t acting or feeling normal, is a good reason to isolate the horse until your veterinarian can determine exactly what is wrong.
You should group horses by biosecurity risk (age, breeding status, use, health) and in small groups (for example, mares and foals, or traveling horses) so there can be more efficient containment in the event of a disease outbreak.
Bringing newcomers in should be done carefully. Keep in mind that a horse can carry or incubate illness, shed that disease and not show overt signs of sickness. Before admitting a horse to your property, insist on a certificate of veterinary inspection (or CVI, which is a health exam and veterinarian-signed certificate) within a few days prior to entry, as well as a negative Coggins test for equine infectious anemia (EIA). It is also a good idea to ask for a negative fecal exam prior to moving the horse to your place and/or proof that the horse has been dewormed appropriately in the preceding week or two.
Also ask for the horse’s travel history, so you can check to see whether there have been any disease outbreaks at venues the horse might have visited. This can be tracked through the Equine Disease Communication Center (equinediseasecc.org), which continually updates infectious disease reports in horses throughout the country.
If yours is a small farm that has minimal interaction with outside horses, then you can set up an isolation area a good distance away from your resident horses. A minimum distance for controlling spread of equine herpesvirus is at least 30 feet. Other infectious diseases (such as equine infectious anemia or piroplasmosis) have a required distance of 200 yards between suspect or infected horses and other equids. The concept of isolation is not just about the distance; it is also about the concept and implementation of multiple biosecurity practices.
Larger facilities should also encourage isolation procedures, but often there is more pushback, especially in big boarding barns where horses often come and go to clinics and events. There should be no opportunity for nose-to-nose contact or shared watering vessels between resident horses and those traveling or newly entering the farm. Horses brought in only for lessons or clinics should have no contact with residents on the farm.
Stabling in the barn can also be a problem. One concern is that the airflow within barns can move pathogens (e.g., influenza and rhinopneumonitis viruses) through the air.
Ideally, a newcomer should stay completely out of touch with other horses for two to three weeks to ensure that he isn’t incubating disease. The length of time for isolation is dependent on knowledge of the horse’s health status and the health management program at the horse’s previous stabling.
All feeding and cleaning chores should be provided to the newcomer only after taking care of resident horses. Watering hoses should not touch the buckets or water within the containers. Equipment such as manure buckets, rakes, wheelbarrows, tractors, blankets, grooming tools and tack shouldn’t be shared between the isolation area and the resident horses. Tools and implements used in an isolation area should be appropriately labeled so they aren’t inadvertently mixed in with the resident herd equipment. Color-coding of buckets is also a useful technique to designate what is used where; highest risk areas might use red, for example. Good signage can also impress people about the location and seriousness of keeping the isolation area isolated.
Observe an incoming horse closely and keep a daily log of rectal temperature, attitude, appetite, and manure and urine output. Educate yourself about normal vital signs, so you know when a horse isn’t quite right. Have your veterinarian immediately investigate any signs of malaise, fever, diarrhea, cough, ocular or nasal discharge, or neurologic instability.
Another important consideration is that personnel who come in contact with horses on the farm should understand your isolation requirements. This includes barn help who feed and muck, trainers, farriers, veterinarians, alternative therapists, bedding suppliers, hay delivery people and fence repair persons, to name a few. These people come across many horses in their daily rounds and there is the potential to bring disease along with them on their hands, their clothing, and even within their noses.
Handwashing with liquid soap in between handling different horses is simply a good hygienic practice for everyone to follow. A general rule is to sing “Happy Birthday” twice while washing your hands. Hand sanitizers with a minimum of 61% alcohol can also be used if hand washing isn’t available, and if there is only minimal contamination on the hands. An appropriate amount (2-3 cm diameter or about an inch) of hand sanitizing gel must be applied, rubbed in well, then allowed to dry for 15-20 seconds.
Some farms require that every visitor sign a visitor log so there can be a traceback should an outbreak occur. When possible, request that all visitors park away from barns, paddocks and pastures. Ask everyone to be circumspect about visiting your farm if they have encountered any sick or not-quite-right horses. If they have, then request that they come back another day once cleaned up, in fresh clothing and footwear, and to at least disinfect footwear in a bactericidal and viricidal footbath.
Throughout the farm, dedicate implements—such as shovels, rakes and pitchforks—with separate uses for either manure cleanup or application of bedding, but not both. Consider the direction of water drainage, so there is no chance of contamination of any part of the farm from any other part. Manure management and the elimination of standing water are important to minimize flies and mosquito vectors that can carry disease.
Don’t forget that children and small animals (cats and dogs), as well as wild animals (rodents, raccoons, opossums, etc.), also can carry disease around a farm. The cats, dogs and children are manageable to some extent, although wild animals are not. Remove wild animal attractants and store feed supplies within animal-proof containers, rooms or buildings. Clean up any spilled or leftover feed and remove trash regularly.
It is often difficult to figure out what to do with horses that travel regularly off the farm and back again. Do you isolate them into separate areas altogether, or reintegrate them back into the herd or barn? Many horse owners are lackadaisical about following biosecurity protocols in these situations, especially during a busy training and competition season.
If no special measures are taken on the farm, then, at the very least, caution should be taken when away. These protocols are discussed in the next section. As added security against disease, it helps to segregate traveling horses into their own group on the farm and with as much distance as possible from resident, non-traveling horses.
Off the Farm
For horses traveling to and from the farm to clinics, shows and events, biosecurity practices are particularly important. In a perfect world, all horse event managers would require entry only if every horse has a current certificate of veterinary inspection (CVI) and a negative Coggins test, as well as appropriate immunizations against equine influenza and rhinopneumonitis. While these tests and procedures don’t guarantee that a horse isn’t incubating a disease at the time of entry, this protocol can go a long way toward minimizing exposure of all horses at a venue by keeping out those that could have a problem.
The thing to keep foremost in mind is that there should be no nose-to-nose contact between your horses and horses from different farms. This concept also applies to touching or handling other people’s horses—just don’t. Put up signs at your stabling asking that no stranger touch or feed your horses.
In fact, if your horse is going to be stabled in a stall that has been used by others, cleaning and disinfection of walls, water vessels and other smooth surfaces can go a long way toward ridding secretions and contaminants from your horse’s environment. Remove residual feed from the stall and rake everything from the floor. Scrub surfaces to remove as much organic debris as possible using detergents (for example, liquid Tide) that break down organic material.
Don’t pressure wash, as this tends to aerosolize bacteria with the possibility of moving it into areas that you can’t see or reach, such as the rafters and ceiling. As much as 90% of bacteria can be eliminated from concrete surfaces with appropriate cleaning techniques. Allow sufficient drying time before the next steps; otherwise, pathogens might remain on surfaces.
Apply a disinfectant labeled for use against viruses and bacteria by following the manufacturer’s directions. This targets the remaining 6-7% of microbes. Virkon-S is highly acclaimed as a disinfectant against many viruses and bacteria, while accelerated hydrogen peroxide products (Virox) are the gold standard. These contain surfactants, wetting agents and chelating agents, all of which facilitate penetration.
Virox is fairly broad spectrum and tends to work better than other products within the presence of light debris and on rougher surfaces while not being corrosive. Contact time should be at least one to five minutes. A list and an explanation of effective disinfectants can be found at the Center for Food Safety & Public Health (cfsph.iastate.edu/Disinfection).
Only use feed and watering containers that you have brought for your horse, and be careful that hoses used to fill watering vessels haven’t been contaminated in other horses’ water sources. Refrain from filling your horse’s water buckets from tanks commonly used by other horses.
When you dispose of your horse’s water, avoid emptying buckets where drainage might impact other horses; watering sources contain nasal secretions, saliva and other potentially communicable material. As you walk your horse around a property, don’t let him snuffle through leftover piles of hay or spilled grain, as these have likely been exposed to other horses’ mouths.
For a daylong event, it is often best to simply tie your horse to your trailer to avoid interaction and contact with other horses or stabling where other horses have been. Don’t share tack, blankets or grooming equipment with anyone else. When warming up your horse in a common exercise area, avoid direct contact between horses and don’t tie your horse to a post or any other tie supports that might have had other horses’ noses or mouths contacting it.
Lest we forget other potential infectious disease vectors at public events besides horse, water, human and equipment, keep your dog in check rather than letting it roam. It doesn’t hurt to ask management to advise that all dogs be restrained appropriately at a public equine event.
It is important to continually monitor horses once they have returned from an outside venue. One excellent means of identifying a looming problem is taking twice-daily rectal temperatures. Watch for any abnormal clinical signs, such as reduced appetite, listlessness, diarrhea, nasal discharge, cough or any signs of discomfort or incoordination. Advise your veterinarian of any suspicion of a problem so you can get an early jump on containment.
Clean and disinfect all equipment used away from the farm—wheelbarrows, rakes and manure buckets, for example—and keep that equipment in a separate location. You might even store show equipment within the horse trailer, so it is ready for the next adventure away from home. That also lets you know it is clean and disinfected. Tack and grooming equipment should be thoroughly cleaned and disinfected where possible.
Horse trailers also move on and off the property, with horses and horse secretions abundant on the interior surfaces. As an example, influenza virus can remain infective in this kind of dark, cool, moist environment for seven to 10 days. Herpesvirus can remain infective in manure for up to 35 days.
Remove all soiled feed, water and manure; dispose of these away from the resident herd, either in dumpsters or in compost piles. Trailers are best parked away from the resident horses, and they should be cleaned and disinfected as often as possible—especially after returning from an off-site location. Spray trailers inside and outside with pesticides to help limit infection brought in by insect vectors.
Have a plan at the ready in case something happens and an outbreak occurs on your farm. Know in advance where you will move sick horses so they are away from the others; how to monitor every horse on the property; and the logistics of caring for both well and sick animals during an outbreak. Consult with your veterinarian for details on how best to accommodate this situation.
The Bottom Line
Biosecurity strategies are part of waging a war on equine infectious disease not just on your farm, but also around the country.
While these efforts might, at first glance, seem labor intensive, keeping your herd’s health paramount through simple biosecurity steps can save you from great difficulty, expense and intensive labor.
The objective of good biosecurity practices is to prevent an infectious disease outbreak in the first place, and to keep your animals as “healthy as a horse.”
- The California Biosecurity Tool Kit is an excellent resource for veterinarians, event managers and horse owners: www.cdfa.ca.gov and search for “biosecurity toolkit.” This article has links to downloadable PDFs on biosecurity.
- AAEP’s Biosecurity Guidelines, a summary of biosecurity information, can be found by going to www.aaep.org and searching for “biosecurity guidelines.”
- For comprehensive information on standard operating procedures for biosecurity, please refer to Colorado State University’s Infection Control and Biosecurity Standard Operating Procedures manual at csu-cvmbs.colostate.edu and search for “infection control and biosecurity standard operation procedures.”
- For immediate alerts on infectious disease outbreaks and information about Biosecurity, refer to the Equine Disease Communication Center website at equinediseasecc.org and click on the top tab for Biosecurity.