Equis ISSN 2398-2977

Pharynx: collapse

Contributor(s): Christopher Brown, Paddy Dixon, Nicola Menzies-Gow

Introduction

  • Cause: idiopathic dynamic obstruction of the upper respiratory tract due to collapse of the nasopharyngeal walls during exercise, obstructing air flow.
  • Signs: inspiratory noise, reduced performance.
  • Diagnosis: signs, endoscopy.
  • Treatment: none.
  • Prognosis: fair to guarded.

Pathogenesis

Etiology

Predisposing factors

Specific

  • Damage to phyarngeal innervation, eg following guttural pouch infection.

Pathophysiology

  • Neuromuscular disorder of pharyngeal musculature.
  • Neuromuscular fatigue of the tensor veli palatini plus strong negative inspiratory pressures during fast exercise → pharyngeal collapse → airway obstruction → reduced performance and respiratory noise.
  • May be exacerbated by head/neck position.

Timecourse

  • Acute to chronic.

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.
  • Franklin S H (2008) Dynamic collapse of the upper respiratory tract: A review. Equine Vet Educ 20 (4), 212-224 VetMedResource.
  • Petsche V Met al (1995) Effect of head position on upper airway function in exercising horses. Equine Vet J Suppl 18, 18-22 WileyOnline.
  • Smith C M, Taylor R J & Dixon P M (1994) Unilateral ventral displacement of the roof of the nasopharynx as a cause of stridor in a pony. Vet Rec 134 (6), 140-141 PubMed.

Other sources of information

  • Parente E J (1998) Dynamic obstruction of the pharynx. In: Proc World Equine Airway Symposium.
  • Parente E J (1995) Correlation between standing endoscopic examinations and those made during highspeed exercise in horses - 150 cases. In: Proc Am Assoc Eq Pract. pp 170.


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