Examination with an endoscope is a routine procedure for racehorses. Scoping can reveal exercise-induced pulmonary hemorrhage (bleeding), airway obstructions, paralyzed arytenoid cartilage (flappers), guttural pouch infections, and the cause of coughs or nasal discharge. Pre-purchase examinations include scoping to assess the health and correctness of the throat and airways.
It is not unusual for a veterinarian, especially at horse sales, to scope a list of horses for multiple clients. As with any medical instrument, disinfection between uses and proper handling is paramount to prevent the spread of disease.
Former WinStar Farm co-owner Bill Casner suspects a dirty scope knocked 9-2 morning-line favorite Colonel John out of the Grade 1 Santa Anita Handicap in 2009 (G1).
“We cannot definitively be certain that the exposure came from the scope, but the timing was apparent,” Casner said. “There were no other horses in the entire barn, front and back, that had temps or got sick except him. He had his own bridle that was not used on other horses. Knowing that incubation periods are generally two to five days, we backtracked through his schedule. He worked five days before the Big 'Cap and was scoped afterwards. This was four days before the fever spike. It was probably coming on the evening before the race.”
After that incident, Casner purchased an endoscope for his trainer, Eoin Harty, and he had all of Harty's assistants who would handle the scope trained in the proper disinfection, handling, and storage of the instrument. All veterinarians who work on Casner's horses are required to use only that endoscope on his horses.
“That was in 2009, and we have not experienced an infection since then that we could attribute to a contaminated scope,” Casner said.
He also is concerned about the cavalier way some veterinarians handle endoscopes at horse sales, which he said is a huge concern of consignors.
“The general procedure is to wipe them off with a Handi-Wipe and then throw them back over the shoulder and handle them with unwashed hands – you will never see them use latex gloves,” he said.
Dr. Fairfield Bain, D.V.M., former clinical professor of equine internal medicine at Washington State University, is now equine technical services veterinarian for Merck Animal Health. Bain is board certified in veterinary internal medicine, veterinary pathology, and emergency and critical care.
“This is something that needs discussion in veterinary circles,” Bain said. “Most respiratory diseases can be transmitted by fomites, such as an endoscope, particularly equine herpesvirus, influenza, and strangles. Thus, it is extremely important to disinfect endoscopes between each patient.”
Bain said effective disinfection is easier to manage in a hospital setting than it is at the sales, on the track, or at a training center, where it is more likely that large numbers of horses would be scoped in succession.
He explained the proper procedure veterinarians should follow for disinfecting endoscopes:
“In situations where multiple patients are being examined, as in a production line, chlorhexidine cleaning of the external aspect, as well as flushing the channel should be done,” he said. “Scopes usually have a small channel that runs the length for passage of catheters, biopsy devices, etc. Chlorhexidine is considered the 'standard of care' in most situations, but true disinfection would require more extensive, time-consuming sterilization using other products requiring prolonged contact time. Most institutions would likely use a glutaraldehyde solution.”
After receiving reports of cross-contamination with human bronchoscopes, the U.S. Food and Drug Administration issued a safety communication in September 2015 that emphasized the failures in cleaning and disinfecting that could spread disease:
►Lack of pre-cleaning at point of use. Pre-cleaning typically includes surface wiping and channel flushing to prevent drying of blood, tissue and other biological debris;
►Failure to perform thorough manual cleaning before high-level disinfection or sterilization;
►Failure to flush or brush channels;
►Use of expired detergent or high-level disinfectant;
►Insufficient flushing, rinsing, and/or drying after high-level disinfection.
►Continued use of devices despite integrity, maintenance, and mechanical issues, including:
–Persistent device channel kinks or bends;
–Channel wall scratches, divots, or crevices;
–Holes, cracks, or other imperfections in the distal end;
►Use of repaired or refurbished devices using out-of-specification parts; and
►Use of devices despite residual material in the instrument or suction channels.
In human medicine, disposable plastic sleeves for endoscopes are used to avoid the spread of disease, but no such sleeve is available for equine endoscopes. Trainer Glenn Thompson and veterinarian Heidi Homze are developing such a sleeve to protect horses.
“For years it has bothered me a great deal that veterinarians are called to scope horses when they are sick or to check for bleeding,” Thompson said. “After the horses are scoped, the scope is quickly wiped down with disinfectant and put back in the case. I cannot imagine the germs and infections that are spread from horse to horse using this method.
“Our sleeve is a disposable one that slides over the scope, and when the job is completed, you slide it off and throw it away.”
Thompson and Homze have applied for a patent and are working on a prototype to submit to veterinary experts for evaluation.
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