Canis ISSN: 2398-2942

Larynx: paralysis

Contributor(s): Daniela Murgia, Jill Sammarco

Introduction

  • Failure to abduct the arytenoid cartilages during inspiration.
  • Cause: can be congenital or acquired. In elderly dogs the acquired form is often considered 'idiopathic'. Most common is idiopathic. Recent evidence strongly suggests that large breed dogs with idiopathic LP may have an underlying chronic progressive, non-inflammatory, degenerative polyneuropathy or neuromuscular disorder and LP may be only one manifestation of a more complex condition (Thiemanet al, 2010).
  • Signs: inspiratory stridor, exercise intolerance, coughing, dysphagia and regurgitation, possibly in association with peripheral neuropathy.
  • Diagnosis: history, breed, clinical signs, examination of larynx under light anesthesia.
  • Treatment: surgery.
  • Prognosis: fair following surgery. Aspiration pneumonia will decrease chance of a favorable outcome.
    Print off the owner factsheet on Laryngeal paralysis to give to your client.

Pathogenesis

Etiology


Congenital or acquired

Acquired

  • 1.Iatrogenic surgical injury to the recurrent laryngeal nerve or any trauma:
    • Direct nerve damage:
      • Cervical or cranial thoracic trauma.
      • Cervical or cranial thoracic neoplasia.
      • Inflammation.
  • 2. Infection.
  • 3. Neuromuscular disease.

Idiopathic

  • Most common in old, large breed dogs.

Neuromuscular disease: polyneuropathy/polymyopathy

  • Paraneoplastic.
  • Immune-mediated.
  • Associated with endocrine disease, eg hypothyroidism Hypothyroidism or diabetes mellitus Diabetes mellitus.
  • Other systemic disease, eg hypocalcemia Hypocalcemia.
  • Myasthenia gravis Myasthenia gravis.
  • Dysfunction of the caudal laryngeal nerves or damage of the dorsal crycoaritenoideus dorsalis muscle with subsequent loss of arytenoid cartilage abduction during inspiration → airway obstruction → increased inspiratory noise and reduced oxygenation of blood.

Predisposing factors

General
  • Age - more common with increasing age.
  • Congenital form: breeding from affected lines?
  • Large breed - idiopathic form.

Pathophysiology

  • Reduced neurological/muscle function → reduced abduction of arytenoid cartilages on inspiration.

Timecourse

  • Progressive stridor, over months/years.
  • Often acute crisis develops in hot weather, ie first summer day following development of signs.

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.
  • Jeffery N D, Talbot C E, Smith P M & Bacon N J (2006) Acquired idiopathic laryngeal paralysis as a prominent feature of generalised neuromuscular disease in 39 dogs. Vet Rec 158 (1), 17 PubMed.
  • MacPhail C M & Monnet E (2001) Outcome of and postoperative complications in dogs undergoing surgical treatment of laryngeal paralysis - 140 cases (1985-1998). JAVMA 218 (12), 1949-1956 PubMed.
  • Rudorf H , Barr F J & Lane J G (2001) The role of ultrasound in the assessment of laryngeal paralysis in the dog. Vet Radiology &Ultrasound 42 (4), 338-43 PubMed.
  • Ridyard A E, Corcoran B M, Tasker S et al (2000) Spontaneous laryngeal paralysis in four white-coated German shepherd dogs. JSAP 41 (12), 558-561 PubMed.
  • White R A S (1989) Unilateral arytenoid lateralization - an assessment of technique and longterm results in 62 dogs with laryngeal paralysis. JSAP 30 (10), 543-549 Wiley Online Library.
  • Venker-van Haagen A J, Bouw J & Hartman W (1981) Hereditary transmission of laryngeal paralysis in Bouviers. JAAHA 17 (1), 75-76 VetMedResource.

Other sources of information

  • Aron D N (1989)Laryngeal paralysis.In:Current Veterinary Therapy X, Small Animal PracticeEd: Kirk R W. pp 343-353.


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