Entrapped Epiglottis - The Vet's Friend

by John Tuckfield ATBC www.atbc.com

One of the joys of owning horses is the mid morning call from the trainer, who, after exchanging pleasantries, passes you over to the vet. Even the most optimistic among us would soon realise that this is hardly likely to be good news.
The horse in question had shown some ability on the trainingtrack. Her regular work partner had won a number of races, yet found it difficult to keep up. She carried this promise onto the city track where she made her debut. The jock returned in raptures promising the usual" you're going to have a lot of fun with her."
The wheels feel off in subsequent races. She would show excellent gate speed and then just fade when the pressure was applied. Her work had dropped off too. No obvious explanation. Then some bright spark noticed a strange sound in her breathing on the completion of her work. An endoscope identified an entrapped epiglottis.
Now this sounds particularly nasty. I understand that the epiglottis is a triangular piece of cartilage that covers the entrance to the larynx. Its purpose is to stop food from entering the larynx and trachea while swallowing. The epiglottis is covered by mucous membranes which are thin layers of epithelium (cells). If these membranes are loosely attached, they can flip over the epiglottis and trap it in its resting position. To cut a long story short, the horse cannot accomplish reflex swallowing necessary to clear the pharynx of secretions during high speed galloping. The result is that the horse inhales more air than it can exhale causing the gradual build up of reserve gas within the lung and an impaired racing performance.
This can be hard to identify because there is often no noise production during galloping. Rather the horse exhibits violent coughing and/or signs of choking when pulled up. Riders are often tricked into believing that the horse has merely been holding its breath, or report a great exhalation sigh when pulled up.
Now the vets seem to love this condition, because it is one that they can fix with reasonable success. As one American vet said" ..the next time your trainer tells you that the horse has a respiratory problem, wish for an epiglottis entrapment !" It's one of the best things that can happen."
Mild cases can be re citified by medical treatment and rest. Surgical correction is required for more advanced and persistent cases.
There are two common methods; laser surgery and trans -oral surgery.
Laser surgery is performed using an endoscope to guide the laser to the epiglottis in order to remove the extra membrane. The procedure can be performed on a standing horse under sedation.
The oral surgery involves the administration and risk of a general anesthetic. Entry is then gained via the mouth from where the entrapped fold is released by slicing the fold using a special instrument shaped like a hook with a cutting edge (curved bistoury). In each case, convalescence involves a couple of weeks stall rest on decreasing amounts of anti-inflammatory drugs, such as bute. Three-weeks after the operation the horse is re-scoped and if there is no swelling can return to full work.
It is claimed that most horses seem to recover well and quickly return to competition. One spectacular success appears to have been an American trotter named Sanoran Sunrise. His entrapment didn't respond to medication or laser surgery, but following oral surgery he returned to racing. he has won 37 races and amassed almost US $500,000 in prizemoney. In 2002, aged 9, he won a Breeders Cup.