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Basics ⬇

Outline

BASICS

Overview!!navigator!!

  • A result of the loose aryepiglottic mucosa, which normally is on the ventral surface of the epiglottis, enveloping part or all of its dorsal surface
  • Usually, the epiglottis remains in its normal position, but the condition can occur concurrently with DDSP
  • Leads to varying degrees of respiratory compromise and exercise intolerance
  • Most often diagnosed during resting endoscopy because the entrapment is persistent
  • Also can occur intermittently
  • Severity can significantly impact the outcome after treatment

Signalment!!navigator!!

  • Affects primarily Thoroughbred and Standardbred racehorses
  • Other breeds or horses engaged in other activities rarely are affected
  • Rarely seen in older noncompetitive horses, associated with a cough
  • Can occur at any age
  • No sex predilection

Signs!!navigator!!

  • Exercise intolerance is the most frequent chief complaint
  • Abnormal respiratory noise may be present
  • Other signs—coughing, dysphagia, nasal discharge

Causes and Risk Factors!!navigator!!

  • The cause is unknown
  • Racing is the most significant risk factor
  • Horses with a small epiglottis are predisposed
  • An association exists between epiglottic entrapment and DDSP

Diagnosis ⬆ ⬇

Outline

DIAGNOSIS

Differential Diagnosis!!navigator!!

  • Epiglottiditis—swelling of the epiglottis smooths out the normal edges and distorts the vascular pattern, but there is no membrane over the epiglottis
  • Epiglottic deformity/hypoplasia—there may be varying degrees of deformity, but there is no membrane over the epiglottis
  • DDSP—the outline of the epiglottis is not visible

Imaging!!navigator!!

  • Upper airway endoscopy at rest—the most common diagnostic technique. The triangular-shaped epiglottis remains visible, but the entrapping membrane obscures the normal serrated edge and vascular pattern of the epiglottis. The normal vasculature consists of 2 vessels that extend toward the apex and that arborize into smaller vessels toward the edge of the epiglottis. Swallowing may induce an intermittent entrapment. With chronicity, the membrane becomes thickened and, sometimes, ulcerated. Infrequently, entrapment can lead to epiglottic deformity that may not be apparent until after the entrapment is resolved
  • With concurrent DDSP, it is difficult to see the entrapment. Close inspection may reveal another edge of membrane before the dorsal surface of the epiglottis is apparent. A bulge into the palate is sometimes present
  • Skull radiography—the convex shape of the epiglottis is obscured on lateral radiographs

Other Diagnostic Procedures!!navigator!!

  • Exercising endoscopy may be required for the diagnosis of intermittent entrapment
  • Visualization of the membrane below the epiglottis with the use of sedation, local anesthetic, and bronchoesophageal graspers can reveal the presence of ulceration that could indicate previous intermittent entrapment
  • Arterial blood gases during exercise are typically normal when concurrent abnormalities are not present

Treatment ⬆ ⬇

TREATMENT

  • Surgical correction of the simple, nonulcerated entrapment entails axial division of the entrapping membrane in the standing horse with sedation and topical anesthetic. The division is performed with direct visualization, employing a laser fiber through the instrument portal of a videoendoscope. Axial division also can be performed with a hooked bistoury, typically under endoscopic guidance
  • Very thickened, ulcerated entrapping membranes often require surgical resection of the tissue. This can be approached through a laryngotomy under general anesthesia, or via transendoscopic laser surgery in the sedated horse

Medications ⬆ ⬇

MEDICATIONS

Drug(s) of Choice

  • Anti-inflammatory drugs (dexamethasone, phenylbutazone) and throat sprays (10 mL of a Furacin (nitrofurazone)-based solution with 2 mg of prednisolone in a 1 mL solution BID) for several days postoperatively
  • Antimicrobials are advised in cases of thickened membranes or ulceration, but may not be necessary in an uncomplicated entrapment

Follow-up ⬆ ⬇

FOLLOW-UP

  • Perform endoscopy postoperatively and before resuming training; further examinations depend on change in performance
  • It may be valuable to evaluate the ventral surface of the epiglottis prior to determining a return to exercise when the membranes are particularly thickened or ulcerated or a resection was performed
  • Epiglottic entrapment has a very low recurrence rate

Miscellaneous ⬆ ⬇

Outline

MISCELLANEOUS

Abbreviations!!navigator!!

DDSP = dorsal displacement of the soft palate

Suggested Reading ⬆ ⬇

Aitken MR, Parente EJ. Epiglottic abnormalities in mature nonracehorses: 23 cases (1990-2009). J Am Vet Med Assoc 2011;238(12):1634–1638.

Epstein KL, Parente EJ. Epiglottic fold entrapment. In: McGorum BC, Dixon PM, Robinson NE, Schumacher J, eds. Equine Respiratory Medicine and Surgery. Philadelphia, PA: WB Saunders, 2006:459–466.

Lacourt M, Marcoux M. Treatment of epiglottic entrapment by transnasal axial division in standing sedated horses using a shielded hook bistoury. Vet Surg 2011;40(3):299–304.

Author(s) ⬆

Author: Eric J. Parente

Consulting Editors: Mathilde Leclère and Daniel Jean