"BioSecurity" on the backstretch

Article by Ken Snyder

"BioSecurity" on the backstretch

Cleanliness, or biosecurity, is essential to horse health and is at the core of minimizing infectious disease outbreaks and subsequent quarantines. Failures in biosecurity can mean canceled race days; idle trainers; and most important and awful, dead or injured horses.

"BioSecurity" on the backstretch

Recent history reveals the importance of biosecurity on both the racetrack and also Thoroughbred breeding farms. In 2021, a life-threatening Rotavirus B outbreak in foals swept through farms in Central Kentucky, taxing farm staff and management with contagion containment. 

More recently, in 2022, an outbreak of equine Herpesvirus-1 at Churchill Downs resulted in a quarantine of as many as 13 horses in one barn. Contagiousness of this EHV-1 meant horses even indirectly exposed to horses with the virus were also quarantined in two other barns.  

EVH-1 isa far more serious threat in that more horses risk exposure on racetracks than on a farm. The virus causes respiratory disease, neonatal death, and neurologic disease, EHM (equine herpesvirus myeloencephalopathy). EHM is often fatal and if not, can leave long-term problems. Symptoms presenting EHM are heart-rending: Horses will lack coordination, have weakness or paralysis in some or all of their limbs, and become unable to balance or stand.

"BioSecurity" on the backstretch

Contact and contagion are the dangers to horse health with viruses like EHV-1 or rotavirus B. Horses travel, and Kentucky might be the busiest crossroad in the world with Thoroughbreds coming in from all points in the country and world and traveling out to racetracks out-of-state and, of course, foreign countries. Experts agree that every effort has to be made in this state and elsewhere with biosecurity to prevent repeats of what happened last year and in 2021. 

They also are in agreement that trainers are the first line of defense.   

Because they see and care for horses daily, trainers will be the first to note abnormalities or symptoms of disease, according to Dr. Stuart Brown, vice president of equine safety at Keeneland Race Course.

“Trainers are the sentinels, the keepers of horse health, them and their attending veterinarians,” he said. “They're at the forefront of working with regulatory veterinarians as well as the state veterinary offices to maintain a healthy population of horses.”

The consensus among industry people like Brown is that trainers, with only a small minority of exceptions, do an excellent job because so much is at stake.

“By and large, they’re all very attuned to disease transmission,” echoed Dr. Will Farmer, equine medical director for Churchill Downs and all other racing properties. 

They have to be, he added. “If a trainer has a sick horse, a groom is taking care of it and multiple horses. There’s the possibility of spreading a disease. Trainers are very keen on biosecurity.“ 

Trainers, especially, must be sensitive to biosecurity in their barns as they move their stable from one race meet to another and new stalls for their horses. 

“I’ve shipped everywhere—Gulfstream, Tampa, New York a lot, Laurel a lot,” said Ian Wilson, assistant trainer to Graham Motion, naming only a few of the destinations for horses at the Fair Hill Training Center in Maryland.

"BioSecurity" on the backstretch

He’s encountered conditions he described as “generally good.” 

“You never walk into a stall and say, ‘This one needs another bag of shavings or another bale of straw.’ 

“Where our concern lies is what you don’t know. A clean stall and a dirty stall sometimes don’t look that different.” 

Receiving barns, which especially should be as pathogen-free as possible, is not guaranteed. “In New York, I know the gentleman who takes care of the receiving barn and he does a really, really, nice job of it. I’ve watched him clean a stall, and he does it properly. In other places, I’ve seen them pick over a stall really quickly, and off they go.”

While disease outbreaks are sporadic, the goal, of course, is minimizing the maximum potential for occurrences. A mantra for Brown at Keeneland is “the solution to pollution is dilution.” In other words, every resource—human and inanimate—should be brought to bear to combat the potential for disease development, particularly with the cleaning and disinfecting of stalls. Every measure, however, will only dilute or reduce issues that arise.

While receiving barns will have straw down and should be clean, standard operating procedure for trainers moving horses from a barn they’ve occupied to another location and unfamiliar stalls is cleaning and disinfecting before another horse can move in. Stalls are mucked daily and cleaned, but disinfecting is a must. Frequency, though, varies among trainers; some might disinfect weekly, others only monthly.  

"BioSecurity" and stable cleanliness

At Keeneland, the maintenance team follows departed trainers and does a second disinfecting to ensure the next occupant gets a clean environment. “Our team will go in, and they’ll basically strip and clean (disinfect) all of the stalls,” said Brown. “They’ll be left for a period of time for desiccation (allowing stalls to dry out). 

“Getting those stalls tossed out and then having them air out and dry as well as being inspected becomes a part of any kind of biosecurity protocol.“ 

Trainers, with few exceptions, follow guidelines prescribed by the Equine Disease Communication Center to one degree or another. These include scrubbing surfaces with warm, soapy water to remove any traces of organic matter (basically anything that comes out of a horse); allowing the surface to dry; applying a disinfectant; allowing the surface to dry after the application of a disinfectant; and disinfecting crossties if in use. 

The choice of disinfectant is at the discretion of a trainer or attending veterinarian. Brown said his maintenance team uses products recommended by the USDA or other regulatory bodies that are specified for controlling the spread of potentially infectious pathogens.

He is investigating a new “delivery system” of a disinfectant from a firm in Nicholasville, Ky., just south of Lexington, produced by Atmosphere Supply. The firm supplies a foaming product for farms of all types that have applications (literally) for racetrack stalls.

Peter Healy, business development manager for the firm, authored a manual, titled Biosecurity for the Equine Industry, after Thoroughbred farm personnel sought help during the rotavirus B epidemic. Healy’s company was asked to assess and critique biosecurity protocols and other practices. “Everybody was in a panic with this new rotavirus back in 2020,” he said.

One key recommendation right off the bat from Healy was to not use bleach. “It is for hard (non-porous) surfaces, not for wood. It does absolutely nothing when applied to wood and could possibly be harmful to a horse.” 

"BioSecurity" at racetracks

Other disinfectants like hydrogen peroxide have the potential to be caustic or acidic and also hazardous. “Horses rubbing against a stall wall are going to come in contact with whatever has been applied,” Healy said.

One particular issue is the application of a disinfectant. Wiping down or spraying with a liquid in a dark stall means the possibility that coverage might be incomplete. A liquid will also run off quickly, according to Healy. The foam disinfectant produced by his company solves both problems and dries in only 10 minutes. Use or frequency of use is at a trainer’s discretion, but it could be applied daily. 

Healy also recommends any product containing hypochlorous acid, primarily a salt and water mixture, that can be sprayed daily even while a horse is in the stall, as ingestion will not harm them.

Other measures to battle pathogens or disease-producing agents are largely a matter of common-sense hygiene. Water buckets at the end of a shedrow that every horse passing by can drink from are asking for disease to spread.

“Equipment contacting a horse can also be a source for contamination,” said Brown. “I know two or three trainers that have started dipping chains and shank clips in a water-diluted Nolvasan solution.” Nolvasan is a readily available skin and wound cleanser. It helps prevent disease spread if a hotwalker is going from horse to horse with the same shank, according to Brown.

"BioSecurity" when making feeds for horses

Pathogens are generally organic but can be carried by humans. Here, too, there are preventive measures. Farmer at Churchill Downs noted that some trainers there are having their help wear gloves at feed time as they mix feed and add supplements. “That’s a proactive approach. They recognize they don’t have control over barn help 24/7,” he said.

Is there a day when grooms and hotwalkers are wearing gloves all the time, or stalls with a “last disinfected” sheet with dates posted on each?  All who were questioned for this story can’t see it, but similar and more stringent measures are already in place in Europe. At some racetracks in France, each stall will have a plastic seal that someone must break to enter—a guarantee that a stall has been disinfected. 

"BioSecurity" on the backstretch

Over there, stall bedding and cleaning are the responsibility of the racetrack generally as most horses are day shippers. Some trainers have traced ringworm to sanitizing agents used by racecourses. “We are not told what they are using; there’s no real regime. Biosecurity is everything; it’s so important,” said French trainer Ilka Gansera-Leveque.

Gloves, plastic seals, “last disinfected” sheets… Sound far-fetched for American racetracks? Who knows? But if the solution to pollution is dilution…

Equine Herpes Virus-1: An elusive target

By Neil Bryant

Infectious diseases are not uncommon in racehorses in training, breeding stock, and pleasure horses. Some of the more serious diseases can be financially devastating to the animal’s owners and to the equine industry on the whole. Viruses belonging to the herpesvirus family cause some of the most well characterized equine infectious diseases, and the most problematic of these is equine herpesvirus 1 (EHV-1; species Equid alphaherpesvirus 1).

EHV-1 is ubiquitous in most horse populations in the world. It is responsible for major economic and welfare problems causing respiratory disease, neurological disease (mainly seen in adult horses), and abortion and neonatal foal death in pregnant mares. This was most notably highlighted by the multiple abortion outbreak recorded in Hertfordshire, England, between February and April 2016 in fully vaccinated animals (http://www.aht.org.uk/cms-display/interim-report16-april2.html). Studies have determined that EHV-1 is a common cause of abortion. Occasional cases have also been linked to EHV-4 infection, but this is much rarer and doesn’t account for episodes of multiple abortion, as is seen occasionally with EHV-1.

The virus

EHV-1 was first isolated from an equine abortion in the U.S. in the 1930s. At the time of first isolation the vets weren’t sure what it was, but they knew it was infectious. Subsequent genetic analysis much later led to the classification of the virus in the genus Varicellovirus (family Herpesviridae), together with its close relatives equine herpesvirus 4 (EHV-4; species Equid alphaherpesvirus 4) and equine herpesvirus 8 (EHV-8; species Equid alphaherpesvirus 8). Interestingly it is grouped with, and is therefore genetically similar to, the human herpesvirus responsible for chickenpox, the Varicella Zoster virus. Initial infection of horses was thought to occur around weaning, when virus-neutralizing antibodies transferred to the foal from the mare’s colostrum had declined enough to make them susceptible to infection. However, virus has been isolated from foals as young as seven days old with high antibody levels but without any significant clinical signs. Immunity to re-infection after primary infection is relatively short-lived, lasting between three-six months, but it is rare for naturally infected mares to abort in consecutive pregnancies.

Disease processes

The virus first enters the horses’ body via the respiratory tract, usually by direct contact with infected animals, contaminated surfaces, or equipment such as tack or veterinary instruments. Direct contact with infected aborted fetuses or placental tissues is also a major source of virus, which experience indicates can cause serious problems if they occur in open barns or large groups of horses.

Once the cells in the respiratory tract are infected, the virus spreads cell-to-cell until it finds its way to the regional lymph nodes, where it can infect white blood cells called lymphocytes. These lymphocytes circulate through the body carrying the virus with them, which is known as a “cell associated viraemia.” The infected lymphocytes can come into contact with and infect numerous cell types, including cells known as “endothelial cells,” which line the inside of blood vessels of the central nervous system and the pregnant uterus. With EHV-1 infection, these endothelial cells undergo an inflammatory response which can lead to bleeding, cell death, and blood clot formation, which in narrow veins disrupts blood supply. This process results in subsequent tissue damage and serious complications such as placental separation (occasionally with delivery of a virus-negative fetus) and/or leakage of virus across the separating placenta (most frequently with delivery of a virus-positive fetus).

Similar mechanisms play a role in neurological disease, a condition called equine herpesvirus myeloencephalopathy or EHM. This condition is also sometimes referred to as an equine stroke, as it is caused by the cellular inflammatory response rather than direct virus infection of nerve cells, which occurs with some other herpesviruses. Less serious clinical signs of infection can include fever, lethargy, inappetence, enlarged lymph nodes, and profuse clear nasal discharge, although not all infected animals will display clinical signs. Recently published work from the Irish Equine Centre has identified EHV-8 as also being occasionally responsible for abortions in mares.  Cases of EHV-8 abortion have also been detected retrospectively by the Animal Health Trust (AHT) among its pathology caseload, as this virus, which is genetically almost identical to EHV-1, triggers positive results in the EHV-1 tests. The frequency and clinical relevance of EHV-8 at this stage is unclear. Of 100 viruses presumed to be EHV-1 and whose genetic material were recently analyzed by the AHT, three were actually confirmed as EHV-8.

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