- The epiglottis is moderately thickened and caudodorsally displaced (yellow arrows) with a soft tissue band confluent with the epiglottis dorsally in the plane of the aryepiglottic folds (pink arrows). At the same level, there is severe, well-defined, lobular, mass-like thickening of the soft tissues (green arrows).
e: epiglottis
np: nasophaynx
h: hyoid bones
Butler et al.
- The dorsal margin of the soft palate is mildly irregularly marginated.
- In the included caudal maxillary and mandibular arcade, the occlusal margins are moderately irregular, and the crowns and reserve crowns are variably shortened
Conclusions:
- Epiglottic entrapment by aryepiglottic folds with severe epiglottitis/aryepiglottitis and mass-like swelling, most likely representing edema, granulation tissue, and/or fibrosis, possibly exacerbated/induced by the reported prior upper airway surgeries.
- Mild-to-moderate soft palate irregularity, likely palatitis.
- Geriatric dental changes with associated wavemouth malocclusion (limited evaluation).
Endoscopy:
- The epiglottis was entrapped within in aryepiglottic fold and a focal ulcer was present to the left of midline, along with moderate thickening of the soft tissues. The epiglottis could not be freed manually.
- Intermittent dorsal displacement of the soft palate was noted during the exam. Multiple instances occured, some of which were able to be resolved by swallowing and some of which were manually resolved.
Follow-up:
- It was elected to perform trans endoscopic laser assisted axial division of the aryepiglottic tissue to resolve the epiglottic entrapment. Four days later, upper airway endoscopy was repeated and revealed the previous epiglottic entrapment remained resolved and the inflammation within the pharynx and larynx appeared improved.
A little bit more…
- The normal equine epiglottis is a dorsally convex, smooth structure with a nearly vertical base and a pointed, narrow tip that lies at a right angle to the dorsal surface of the soft palate. Its lateral edges appear serrated, and a vascular pattern can typically be seen on its dorsal surface. The aryepiglottic folds attach to its lateral margins (Butler et al., Barakzai et al.).
- Common abnormalities of the epiglottis include entrapment, hypoplasia (shortening), subepiglottic cysts, and ulceration or inflammation (Butler et al.).
- In cases of epiglottic entrapment, the apex and lateral margins become enveloped by the ventral mucosa and aryepiglottic folds, resulting in blunting and shortening of the epiglottis, often with accompanying ulceration. Clinically, affected horses, most commonly Thoroughbreds and Standardbreds, may exhibit exercise intolerance and abnormal respiratory noises at high speeds, though they typically appear normal at rest (Butler et al., Barakzai et al.).
- Radiographically, the epiglottis will be short, blunt, and deviated dorsally or caudally (Butler et al.).
- Endoscopy remains the diagnostic gold standard.
- Potential causes of entrapment remain unclear but may involve inflammation, trauma, infection, or developmental anomalies.
- Treatment may include conservative management, such as with topical anti-inflammatories, or surgical, including various transection techniques. Despite a relatively high complication rate, surgical outcomes can be favorable, with most horses returning to racing and many showing performance improvement. (Barakzai et al.).
- In a study by Hobo et al., epiglottic entrapment by aryepiglottic folds had a 0.6% prevalence. In another study by Russel et al, 26/27 horses raced again; 13/27 improved in handicap, 13/27 decreased handicap.
References:
- Butler JA, Colles CM, Dyson S, Kold S, Poulos P. Clinical radiology of the horse. Oxford: Blackwell science; 2000 Jan 11.
- Brown JA, Hinchcliff KW, Jackson MA, Dredge AF, O’Callaghan PA, McCaffrey JP, Slocombe RF, Clarke AF. Prevalence of pharyngeal and laryngeal abnormalities in Thoroughbreds racing in Australia, and their association with performance. Equine Veterinary Journal. (2005) 37(5): 397-401
- Barakzai, Safia. “Epiglottic entrapment in horses.” (2010): 10.
- Hobo S, Matsuda Y, Yoshida K. Prevalence of upper respiratory tract disorders detected with a flexible videoendoscope in Thoroughbred racehorses. Journal of Veterinary Medical Science. (1995) 57(3): 409-413.
- Russell T, Wainscott M. Treatment in the field of 27 horses with epiglottic entrapment. The Veterinary Record. (2007) 161: 187-189.
