Normal values for radial, peroneal and tibial motor nerve conduction velocities in adult sheep, with comparison to adult dogs.

A technique for measuring motor nerve conduction velocities (NCV) in sheep was developed using 15 clinically normal ewes. Mean +/- SD values were determined for the radial (76.3 +/- 12.5 m/s), peroneal (103.9 +/- 12.7 m/s), and tibial (98.6 +/- 13.1 m/s) nerves. The recording needle electrode was located in the extensor carpi radialis, tibialis cranialis, and gastrocnemius muscles, respectively. Latencies, amplitudes and durations of the proximal and distal evoked compound muscle action potentials are given. To investigate further the unexpectedly high NCVs calculated for the peroneal and tibial nerves, analogous stimulating and recording electrode sites were used in 7 clinically normal dogs. The corresponding canine peroneal (88.1 +/- 8.3 m/s) and tibial (89.2 +/- 12.4 m/s) NCVs were higher than the standard sciatic-tibial NCV recorded from the interosseous muscles (68.9 +/- 5.8 m/s), but not as high as for sheep. Myelinated nerve fiber diameters were measured on semithin transverse sections of peroneal and tibial nerve specimens taken from a clinically normal ewe and bitch. A possible explanation for the relative species difference in the proximal peroneal and tibial NCV values is the presence of fibers in both the peroneal and tibial nerves of the sheep which were as much as 3 mu wider than the largest fibers found in the dog.