Lecture 34- Disorders of the Larynx and Pharynx

Definition of laryngeal paralysis

Failure of arytenoid cartilages to abduct during inspiration → upper airway obstruction.

Innervation of arytenoid abductor muscles

Right and left recurrent laryngeal nerves.

Species affected by LP

Dogs (most common), cats (uncommon).

Potential causes of LP: idiopathic ventral cervical lesion

Trauma, direct trauma, inflammation, fibrosis, neoplasia, other inflammatory/mass lesions.

Potential causes of LP: anterior thoracic lesion

Neoplasia, trauma, postoperative injury.

Polyneuropathy/polymyopathy causes of LP

Idiopathic GOLPP (geriatric onset LP polyneuropathy), immune‑mediated disease.

Endocrinopathy associated with LP

Hypothyroidism.

Other systemic disorders associated with LP

Toxicity.

Neuromuscular disease associated with LP

Myasthenia gravis.

Congenital LP breeds

Bouvier des Flandres, Siberian Husky, Bull Terrier.

Breeds with LP‑polyneuropathy complex

Dalmatian, Rottweiler, Great Pyrenees.

Breed overrepresented for LP

Labrador Retriever.

LP etiology summary

Part of generalized neuromuscular/polyneuropathy complex; trauma/neoplasia of recurrent laryngeal nerves.

LP clinical presentation

Older large‑breed dogs; respiratory distress + stridor; voice change; uncommon in cats.

LP acute crisis presentation

Acute respiratory crisis requiring emergency intervention; history of gagging/coughing when drinking/eating.

LP diagnosis: initial workup

PE; ortho/neuro exam; MDB; thyroid profile; thoracic radiographs.

LP diagnosis: concurrent disease

Evaluate for aspiration pneumonia.

LP diagnosis: laryngeal exam

Performed under light sedation; assess arytenoid movement.

LP diagnosis: rule‑outs

Pharyngeal/esophageal dysmotility; megaesophagus (esophagram/barium swallow).

LP emergency management

Sedation (acepromazine, butorphanol, buprenorphine IV); cool oxygen‑rich environment; dexamethasone IV.

LP surgical treatment

Unilateral arytenoid lateralization (“tie‑back”) — NOT if megaesophagus present.

Tie‑back surgical goal

Increase airway diameter without excessive widening that increases aspiration risk.

Analgesia caution in LP

Avoid pure μ‑agonists (morphine, hydromorphone).

GI motility drug for aspiration reduction

Cisapride (NOT metoclopramide).

LP medical management (if surgery not possible)

Corticosteroids; weight management; exercise/heat restriction; harness instead of collar.

LP prognosis

Fair to good overall; median survival 4.9 yrs post‑surgery (MacPhail 2001); aspiration pneumonia most common complication.

LP prognosis caveats

Guarded if generalized neuromuscular disease or megaesophagus present.

Brachycephalic airway syndrome affected breeds

Boston Terrier, Pug, Bulldog, French Bulldog, Himalayan cat.

BOAS clinical signs

Stertor; GI signs (vomiting/regurgitation); increased inspiratory effort; cyanosis; syncope.

BOAS pathophysiology

Increased intrathoracic pressure from obstructed airflow; concurrent GI disease possible.

Four components of BOAS

Stenotic nares; elongated soft palate; hypoplastic trachea; everted laryngeal saccules.

BOAS severity

One or more abnormalities; severity varies between individuals.

BOAS progression

Increased inspiratory effort → edema → laryngeal collapse.

BOAS diagnosis

Breed + clinical signs; cervical/thoracic radiographs; scoping of oropharynx/larynx.

BOAS treatment goals

Enhance airflow through limited airways.

BOAS treatment: conservative

Minimize stress; limit exercise; cool environment; weight control.

BOAS treatment: surgical

Excise elongated soft palate; remove everted saccules; correct stenotic nares.

BOAS timing of surgery

Early correction (especially stenotic nares) at 3–4 months before clinical signs develop.

Stenotic nares correction

Alarplasty.

Elongated soft palate significance

Causes airway obstruction; contributes to stertor and cyanosis.

Everted laryngeal saccules

Obstructive tissue protruding into airway; surgically removed.

Hypoplastic trachea

Narrow trachea (esp. Bulldogs); contributes to airway resistance.

Laryngeal neoplasia prevalence

Uncommon in dogs and cats.

Laryngeal neoplasia types: carcinomas

Squamous cell carcinoma, undifferentiated carcinoma, adenocarcinoma.

Laryngeal neoplasia types: round cell

Lymphoma (cats most common), mast cell tumor, TVT (rare).

Laryngeal neoplasia types: others

Melanoma; benign neoplasia.

Laryngeal neoplasia clinical signs

Noisy respiration, stridor, increased inspiratory effort, voice change; dysphagia; aspiration pneumonia; palpable mass.

Laryngeal neoplasia diagnosis

Radiographs, CT/MRI, laryngoscopy; FNA/biopsy; staging with LN evaluation + thoracic radiographs.

Laryngeal neoplasia treatment

Surgical excision; laryngectomy + permanent tracheostomy; radiation therapy; chemotherapy (e.g., lymphoma); NSAIDs (COX‑2 inhibition).

DDx for laryngeal masses

Neoplasia, granuloma, abscess, foreign body, cyst, inflammatory mass.