"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…

Antimicrobials in an age of resistance

By Jennifer Davis and Celia Marr

Growing numbers of bacterial and viral infections are resistant to antimicrobial drugs, but no new classes of antibiotics have come on the market for more than 25 years. Antimicrobial-resistant bacteria cause at least 700,000 human deaths per year according to the World Health Organization (WHO). Equivalent figures for horses are not available, but where once equine vets would have very rarely encountered antimicrobial-resistant bacteria, in recent years this serious problem is a weekly, if not daily, challenge. 

The WHO has for several years now, designated a World Antibiotic Awareness Week each November and joining this effort, British Equine Veterinary Association and its Equine Veterinary Journal put together a group of articles exploring this problem in horses.


For more information:  https://beva.onlinelibrary.wiley.com/hub/journal/20423306/homepage/sc_antimicrobials_in_an_age_of_resistance

How do bacterial populations develop resistance?

Certain types of bacteria are naturally resistant to specific antimicrobials and susceptible to others. Bacteria can develop resistance to antimicrobials in three ways: bacteria, viruses and other microbes, which can develop resistance through genetic mutations or by one species acquiring resistance from another. Widespread antibiotic use has made more bacteria resistant through evolutionary pressure—the “survival of the fittest” principle means that every time antimicrobials are used, susceptible microbes may be killed; but there is a chance that a resistant strain survives the exposure and continues to live and expand. The more antimicrobials are used, the more pressure there is for resistance to develop.

The veterinary field remains a relatively minor contributor to the development of antimicrobial resistance. However, the risk of antimicrobial-resistant determinants traveling between bacteria, animals and humans through the food chain, direct contact and environmental contamination has made the issue of judicious antimicrobial use in the veterinary field important for safeguarding human health. Putting that aside, it is also critical for equine vets, owners and trainers to recognize we need to take action now to limit the increase of antimicrobials directly relevant to horse health.

How does antimicrobial resistance impact horse health?

Fig 1. This mare’s problems began with colic; she underwent surgery to correct a colon torsion (twisted gut). When the gut wall was damaged, bacteria easily spread throughout the body. The mare developed an infection in her surgical incision and in her jugular veins, progressing eventually to uncontrollable infection—resistant to all available antimicrobials with infection of the heart and lungs.

The most significant threat to both human and equine populations is multidrug-resistant (MDR) pathogens, including methicillin-resistant Staphylococcus aureus (MRSA), extended-spectrum beta-lactamase (ESBL) producing Escherichia coli, MDR Klebsiella pneumoniae, Pseudomonas aeruginosa, Enterococcus faecium, and rising MDR strains of Salmonella spp. and Clostridium difficile. In an analysis of 12,695 antibiograms collected from horses in France between 2012-2016, the highest proportion (22.5%) of MDR isolates were S. aureus. Identification of ESBL E.coli strains that are resistant to all available antimicrobial classes has increased markedly in horses. In a sampling of healthy adult horses at 41 premises in France in 2015, 44% of the horses shed MDR E.coli, and 29% of premises shedding ESBL isolates were found in one third of the equestrian premises. Resistant E. coli strains are also being found in post-surgical patients with increasing frequency.

Fig 2. Rhodococcus equi is a major cause of illness in young foals. It leads to pneumonia and lung abscesses, which in this example has spread through the entire lung. Research from Kentucky shows that antimicrobial resistance is increasingly common in this bacterial species.

Of major concern to stud owners, antimicrobial-resistant strains of Rhodococcus equi have been identified in Kentucky in the last decade, and this bacteria can cause devastating pneumonia in foals. Foals that are affected by the resistant strains are unlikely to survive the illness. One of the leading authorities on R.equi pneumonia, Dr. Monica Venner has published several studies showing that foals can recover from small pulmonary abscesses just as quickly without antibiotics, and has pioneered an “identify and monitor” approach rather than “identify and treat.”  Venner encourages vets to use ultrasonography to quantify the infected areas within the lung and to use repeat scans, careful clinical monitoring and laboratory tests to monitor recovery. Antimicrobials are still used in foals, which are more severely affected, but this targeted approach helps minimize drug use.



What can we do to reduce the risk of antimicrobial resistance?

The simple answer is stop using antimicrobials in most circumstances except where this is absolutely avoidable. In training yards, antimicrobials are being over-used for coughing horses. Many cases are due to viral infection, for which antibiotics will have little effect. There is also a tendency for trainers to reach for antibiotics rather than focusing on improving air quality and reducing exposure to dust. Many coughing horses will recover without antibiotics, given time. Although it has not yet been evaluated scientifically, adopting the identify and monitor approach, which is very successful in younger foals, might well translate to horses in training in order to reduce overuse of antimicrobials.


Fig 3. Faced with a coughing horse, trainers will often pressure their vet to administer antibiotics, hoping this will clear up the problem quickly. Many respiratory cases will recover without antibiotics, given rest and good ventilation

Vets are also encouraged to choose antibiotics more carefully, using laboratory results to select the drug that will target specific bacteria most effectively. The World Health Organization has identified five classes of antimicrobials as being critically important, and therefore reserved, antimicrobials in human medicine. The critically important antimicrobials which are used in horses are the cephalosporins (e.g., ceftiofur) and quinolones (e.g., enrofloxacin), and the macrolides, which are mainly used in foals for Rhodococcal pneumonia. WHO and other policymakers and opinion leaders have been urging vets and animal owners to reduce their use of critically important antimicrobials for well over a decade now. Critically important antimicrobials should only be used where there is no alternative, where the disease being treated has serious consequences and where there is laboratory evidence to back up the selection. The British Equine Veterinary Association has produced helpful guidelines and a toolkit, PROTECT-ME, to help equine vets achieve this.




How well are we addressing this problem?

Disappointingly, in a recent review of prescribing behavior of three “reserved” antimicrobials at first-opinion equine practices in the USA and Canada between 2006-2012 published in Equine Veterinary Journal, only 5% of prescriptions for the reserved antimicrobials enrofloxacin, ceftiofur and clarithromycin were informed by culture and sensitivity testing. There was also an overall trend of increased prescribing of enrofloxacin across the study period, and despite increasing awareness of the challenge of antimicrobial resistance, a decreasing proportion of enrofloxacin prescriptions were based on culture and sensitivity results.


Judicious use of antimicrobials for surgical patients

Antimicrobials are commonly used in the perioperative period. In both human and veterinary medicine, antimicrobial use for surgical prophylaxis has been a target for reducing or eliminating inappropriate antimicrobial administration. The British Equine Veterinary Association recommends administration of penicillin pre- and post-operatively for 24 hours for clean surgeries; penicillin and gentamicin pre- and post-operatively for five days for contaminated surgeries; and penicillin and gentamicin pre- and post-operatively for 10 days for complicated surgeries. Furthermore, for uncomplicated contaminated wounds (e.g., hoof abscesses), antimicrobial therapy is not recommended. A 2018 survey of perioperative antimicrobial use among equine practitioners in Australia revealed that most equine vets selected an appropriate antimicrobial agent. However, the dose of penicillin chosen was often suboptimal, and therapy was frequently prolonged beyond recommendations in all scenarios except for castration. 

Judicious use of antimicrobials through appropriate routes of administration

Fig 4. Using antimicrobials as effectively as possible helps to reduce their use overall. For septic arthritis, intravenous regional perfusion of antimicrobials can achieve very high concentrations within a specific limb. This involves placing a temporary tourniquet to reduce blood flow away from the area while the antimicrobial is injected into a nearby blood vessel. The technique is suitable for some but not all antimicrobial drugs.

Due to increasing isolation of MDR organisms, research into local therapy of “reserved” classes of antimicrobials is of interest. Intravenous regional limb perfusion of ceftiofur sodium may be appropriate for septic arthritis but is less clear cut for osteomyelitis. 

Oral and rectal administration of antimicrobials are common means to provide cost-effective and convenient treatment options for owners. However, these routes of administration can lead to variable absorption and therefore have the potential for subtherapeutic concentrations. Rectal administration of some antimicrobials has been explored in order to provide antimicrobials to horses with diseases that prevent oral administration, such as small intestinal problems or to provide an alternative for horses that find drugs unpalatable and go off their feed. Metronidazole is one of the few drugs for which pharmacokinetic data following rectal administration have been published, but the optimal dosing regimens via this route have yet to be determined.

Clinical conclusions

Given the increasing prevalence of resistant bacteria affecting the equine population, judicious use of antimicrobials is necessary. Trainers and vets must work together to implement this, otherwise before long, we will find we have no effective drugs left. Firstly, in any given situation, we should question whether antibiotics are really necessary.

Appropriate antibiotic selection, as well as choosing the correct dose, frequency, duration and route of administration should all be considered. Veterinarians should encourage culture and sensitivity testing to allow for guided and narrow spectrum therapies whenever possible. It is also important to keep up-to-date with the latest information on drug treatment schedules and be prepared to modify and adapt as new information becomes available. Appropriate antimicrobial stewardship in veterinary medicine will ensure the availability and legal use of antimicrobials remains an option for our equine patients.