Evaluation of Pharyngeal Function in Dogs with Laryngeal Paralysis Before and After Unilateral Arytenoid Lateralization.

Abstract

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. Prospective controlled cohort study. Dogs with laryngeal paralysis (ILP; n = 8) and age/breed-matched (AB, n = 8) and young breed-matched dogs (B, n = 8) were recruited. 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. 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. 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.