Equis ISSN 2398-2977

Epiglottis: cyst - subepiglottic

Synonym(s): Pharyngeal cyst

Contributor(s): Tim Brazil, Graham Munroe, Vetstream Ltd, Nicola Menzies-Gow

Introduction

  • Cause: embryonic remnant of the thyroglossal duct. Most common form of pharyngeal cysts . May also form due to chronic inflammation of sub-epiglottic tissue.
  • Signs: respiratory noise on inhalation and exhalation; poor performance; coughing, dysphagia, nasal discharge.
  • Diagnosis: endoscopy.
  • Treatment: surgical excision.
  • Prognosis: good.

Pathogenesis

Etiology

  • Congenital.
  • Trauma/chronic inflammation.

Pathophysiology

  • Embryonic remnant of thyroglossal duct on ventral surface of epiglottis → persistant epithelial tissue secretes into enclosed space → cyst formation deforms and displaces epiglottis → upper respiratory tract obstruction.
  • The noise results from the presence of a space occupying mass causing distortion of the normal architecture between the larynx and the pharynx.
  • Some authors have suggested they are due to chronic inflammation post-regional trauma in some cases.
  • Occasionally found in older horses with no previous history of upper respiratory tract problems.
  • Occasionally, rupture of the cyst results in a sudden cessation of signs, however the cyst reforms and signs will recur.
  • Rarely, complete obstruction may cause syncope.

Timecourse

  • Introduction to intensive exercise may reveal the condition.
  • Congenital cysts may cause dysphagia and nasal aspiration of milk in neonatal foals.
  • Dysphagia may be more obvious in young foals after weaning.
  • Often incidental findings on endoscopic examination for sale.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Strand E et al (2012) Relative prevalence of upper respiratory tract obstructive disorders in two breeds of harness racehorses (185 cases: 1998-2006). Equine Vet J 44 (5), 518-523 PubMed.
  • O'Neill H & Giorio M E (2010) Obstructive lesions of the equine upper respiratory tract Part 2: Surgical options and expected outcomes: Part 2. UK Vet 15 (5), 4-6 VetMedResource.
  • Saulez M N & Gummow B (2009) Prevalence of pharyngeal, laryngeal and tracheal disorders in Thoroughbred racehorses, and effect on performance. Vet Rec 165 (15), 431-435 PubMed.
  • Kelmer G et al (2007) A novel location and en bloc excision of a thyroglossal duct cyst in a filly. Equine Vet Educ 19 (3), 131-135 VetMedResource. 
  • Dixon P M & Collins N (2004) The equine epiglottisEquine Vet Educ 16 (6), 299-301 VetMedResource.
  • Hay W P et al (1997) Complete upper airway obstruction and syncope caused by a subepiglottic cyst in a horse. Equine Vet J 29 (1), 75-76 PubMed.
  • Tulleners E P (1991) Evaluation of peroral transendoscopic contact neodymium-yttrium aluminum garnet laser and snare excision of subepiglottic cysts in horses. JAVMA 198 (9), 1631-1635 PubMed.
  • Stick J A et al (1980) Subepiglottic cyst in three foals. JAVMA 177 (1), 62-64 PubMed.

Other sources of information

  • Cahn C C H & Munroe G (1997) Congenital Abnormalities of the Mouth and Associated Structures. In: Current Therapy in Equine Medicine 4. Eds: Robinson N E. W B Saunders, Philadelphia. ISBN 0-7216-2633-5.
  • Raker C W (1982) Pharyngeal Cysts. In: Equine Medicine and Surgery. 3rd edn. Eds: Mansmann R A, McAllister E S. American Veterinary Publications, California. Catalog Card No. 81-70196.


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