Electromyographic evaluation of conduction time and velocity of the recurrent laryngeal nerves of clinically normal dogs.

In 25 adult dogs of various breeds, recurrent laryngeal nerve fibers were electrically stimulated at 2 points along their extralaryngeal course. Evoked compound muscle action potentials were recorded in the ipsilateral intrinsic laryngeal muscles, using a percutaneous needle electrode. Latencies, amplitudes, and durations were measured. Latencies were correlated with neck length (r = 0.88 on left and 0.82 on right). Five of the dogs were euthanatized, and the nerve length between the 2 stimulating needle electrodes was measured; calculated conduction velocities (mean +/- SD) were 55 +/- 6 m/s (left) and 57 +/- 6 m/s (right). In 38 additional canine cadavers, the lengths of the exposed left and right recurrent laryngeal nerves were correlated with neck length (r = 0.44 on left and 0.56 on right). A linear regression model is proposed for predicting normal latencies, despite variations in neck length among different breeds of dogs.