The epiglottis is a triangular shaped cartilage located in the throat at the base of the entrance to the airways. During normal breathing, it is situated above the soft palate and facilitates air move- ment. When eating, the epiglottis moves upwards and backwards to allow swallowing and to prevent food from entering the airways.
To allow for such movement, the lower surface of the epiglottis has a loosely attached, elastic mucosa (subepiglottic mucosa). Epiglottic entrapment occurs when the subepiglottic mucosa becomes positioned above the epiglottis, restricting movement.
The most common presenting sign in cases of epiglottic entrapment is abnormal respiratory noise. The abnormally positioned subepiglottic mucosa creates a slightly narrowed airway, as well as increased air turbulence, which creates a harsh respiratory noise.
Horses in a higher plane of work, racehorses for example, can also present with exercise intolerance. In horses performing at high speeds, even mild narrowing of the airway can result in decreased athletic performance, and, as a result, decreased earnings.
Coughing and nasal discharge occur in some cases, as an abnormally functional epiglottis can contribute to disruption of airflow and slightly interfere with the swallowing process. As none of these changes indicate a specific cause of disease,
An incision is made through the abnormally positioned subepiglottic mucosa to release the entrapped epiglottis. The procedure can be performed either under sedation and lo- cal anesthesia or under general anesthesia and typically takes less than 30 minutes.
There are several surgical methods available, namely use of a transnasal endoscopically guided laser, transen- doscopic electrosurgical instrument, or transnasal or transoral curved surgical knife. Surgical excision can also be performed via incision into the airway via the pharynx or larynx, however, these methods will result in an external scar and can contribute to surgical site complications.
These procedures are therefore typically reserved for cases with additional complications.
The potential complications of surgical intervention include thermal trauma to the epiglottis, adhesions, and cicatrix (scar) formation. To reduce the risk of these occurring, horses should receive systemic and topical anti-inflammatory medications. Dorsal displacement of the soft pal- ate can occur regardless of the treatment method employed, particularly when epiglottic hypoplasia is present.
Local inflammation is common following surgical correction of epiglottic entrapment. Horses should therefore receive transnasal endoscopic evaluation each week following surgery until the larynx has a normal appearance.
Throat sprays containing anti-inflammatory agents are also strongly recommended. To reduce inflammation in the laryngeal region; horses require a period of rest following surgery.
Depending on the severity of the condition and the treatment method employed, horses can return to work 3-8 weeks post-operatively, providing transnasal endoscopic evaluation is normal.
Reoccurrence is not uncommon and can be treated by surgical excision of the excess subepiglottic mucosa. The majority of horses with epiglottic entrapment without epiglottic hypoplasia are able to return to their original level of activity.
Press release provided by Diane Furry - Gluck Equine Research Center, Article by Alex Gillen, MA, MS, VetMB, CertAVP, DipACVS, DipECVS, MRCVS