Laryngeal paralysis

From Dog

Laryngeal paralysis is a relatively common neurological disease characterized by loss of motor control to the larynx, resulting in dysphagia, voice changes and involuntary aspiration of food and fluids.

Damaged to any of the four nerves innervating the larynx (right and left recurrent laryngeal nerves and superior laryngeal nerves) can result in partial or complete temporary or permanent laryngeal paralysis.

An underlying polyneuropathy complex is thought to be involved[1] in many cases.

Laryngeal paralysis can be congenital or acquired and is common seen in large-breed dogs such as Labrador Retrievers.

Acquired laryngeal paralysis can occur from trauma or surgical injury during thyroidectomy or compression of the recurrent laryngeal nerve by a cranial mediastinal carcinoma or thyroid carcinoma. More commonly, however, laryngeal paralysis is classified as idiopathic in older dogs.

An hereditary form has been described in Bouvier Des Flandres, Dalmatian, Rottweiler and Siberian Husky breeds and frequently observed in young dogs under 12 months of age[2][3].

Causes include:

Affected dogs usually present with varying degrees of phonation change and respiratory distress which may be of acute or slow onset, depending on cause. These symptoms develop as a result of laryngeal collapse and consequent spatial distortion to the larynx, resulting in physiological airway obstruction[6].

Secondary aspiration pneumonia, pulmonary edema and pectus excavatum may develop in older dogs[7].

Diagnosis is based on endoscopic evaluation of the larynx, often during general anesthesia. A contrast esophagram with videofluoroscopy may be required to make a definitive diagnosis of decreased esophageal motility. Biopsies of laryngeal tissue usually reveal varying degrees of loss of large-caliber nerve fibers, axonal degeneration and neurogenic atrophy.

In acutely dyspneic dogs, supplemental oxygen and sedation with acepromazine or butorphanol may be required. If laryngeal edema is suspected, prednisolone is administered.

With idiopathic laryngeal paralysis, a bilateral ventriculocordectomy can be performed through a ventral median laryngotomy, which is successful in many cases[8].

Alternative treatment methods include partial arytenoidectomy, vocal fold resection, bilateral arytenoid stenting[9] and transverse cordotomy with cuneiform cartilage amputation[10]. Some dogs may require concurrent soft palate resection because prolonged negative airway pressure can increase soft palate length and thickness.

Post-operative complications such as megaesophagus and neurological disease are not uncommon[11].

References

  1. Thieman KM et al (2010) Histopathological confirmation of polyneuropathy in 11 dogs with laryngeal paralysis. J Am Anim Hosp Assoc 46(3):161-167
  2. Venker-van Haagen AJ et al (1981) Hereditary transmission of laryngeal paralysis in Bouviers. JAAHA 17:75-76
  3. Braund KG et al (1994) Laryngeal paralysis-polyneuropathy complex in young dalmatians. Am J Vet Res 55:534-542
  4. Stanley BJ et al (2010) Esophageal dysfunction in dogs with idiopathic laryngeal paralysis: a controlled cohort study. Vet Surg 39(2):139-149
  5. Kvitko-White H et al (2012) Acquired bilateral laryngeal paralysis associated with systemic lupus erythematosus in a dog. J Am Anim Hosp Assoc 48(1):60-65
  6. Nelissen P & White RA (2011) Arytenoid Lateralization for Management of Combined Laryngeal Paralysis and Laryngeal Collapse in Small Dogs. Vet Surg Nov 21
  7. Kurosawa TA et al (2012) Imaging diagnosis - acquired pectus excavatum secondary to laryngeal paralysis in a dog. Vet Radiol Ultrasound 53(3):329-332
  8. Zikes C & McCarthy T (2012) Bilateral ventriculocordectomy via ventral laryngotomy for idiopathic laryngeal paralysis in 88 dogs. J Am Anim Hosp Assoc 48(4):234-244
  9. Cabano NR et al (2011) Effects of bilateral arytenoid cartilage stenting on canine laryngeal resistance ex vivo. Vet Surg 40(1):97-101
  10. Furneaux RW (2010) Transverse cordotomy and cuneiform cartilage amputation for the management of laryngeal paralysis in a dog. Res Vet Sci 89(2):272-274
  11. MacPhail CM & Monnet E (2001) Outcome of and postoperative complications in dogs undergoing surgical treatment of laryngeal paralysis: 140 cases (1985-1998). JAVMA 218:1949-1956