Pharyngeal function in dogs with laryngeal paralysis

Abstract

OBJECTIVE: To evaluate pharyngeal and laryngeal function using esophagography, topical pharyngeal/laryngeal sensitivity testing, and electromyography (EMG) in normal and dogs with idiopathic laryngeal paralysis (ILP) before and after unilateral arytenoid lateralization. STUDY: Prospective controlled cohort study. ANIMALS: Dogs with laryngeal paralysis (ILP; n = 8) and age/breed-matched (AB, n = 8) and young breed-matched dogs (B, n = 8) were recruited. METHODS: Evaluation consisted of esophagography, topical pharyngeal/laryngeal sensitivity testing, and electrodiagnostic testing. Esophagography was performed with liquid and canned phases. Pharyngeal and laryngeal sensitivity was tested by applying a cotton-tipped applicator to the mucosa of pharynx/larynx at anesthetic induction. In all dogs, electrophysiological testing included EMG, direct evoked muscle potentials, motor nerve conduction velocities, and F wave testing. These were performed in the thoracic/pelvic limbs, extrinsic laryngeal muscles, epaxial, and masticatory muscles. RESULTS: Topical pharyngeal and laryngeal sensitivity testing was decreased in LP dogs compared with age-matched healthy control dogs. Esophagram showed dysmotility in the cranial and caudal esophagus. Gastroesophageal reflux was significantly higher in ILP dogs compared with the other 2 groups (P < .03). In all affected dogs, EMG abnormalities were limited to the interosseous muscles of both pelvic and thoracic limbs bilaterally. CONCLUSION: Dogs with ILP not only have recurrent laryngeal nerve (RLN) and pararecurrent laryngeal nerve (pRLN) dysfunction, but may also have concurrent cranial laryngeal nerve dysfunction.