LARYNGEAL PARALYSIS-POLYNEUROPATHY COMPLEX IN YOUNG DALMATIANS

Clinical, morphologic, and morphometric findings are reported in 14 yo ung Dalmatians with laryngeal paralysis. Neurologic signs, including m egaesophagus, were observed in 13 of 14 dogs. Electromyographic abnorm alities included fibrillation potentials and positive sharp waves in l aryngeal, esophageal, facial, and distal appendicular muscles. Neuroge nic atrophy was detected in intrinsic laryngeal and appendicular skele tal muscles. A diffuse, generalized polyneuropathy, dominated by axona l degeneration, was observed in recurrent laryngeal and appendicular p eripheral nerves. Results of quantitative studies, using single teased fiber and cross-sectional nerve preparations, indicated that changes were more severe in distal parts of peripheral nerves, with preferenti al loss of medium sized (5.5 to 8 mu m) and large-caliber (8.5 to 12 m u m) myelinated nerve fibers. Ultrastructural alterations were observe d in myelinated and unmyelinated nerve fibers. The term laryngeal para lysis-polyneuropathy complex is proposed for this apparent dying-back disorder, which is clinically, electrophysiologically, and pathologica lly different from laryngeal paralysis in young Bouvier des Flandres a nd Siberian Huskies. Prognosis for Dalmatians with laryngeal paralysis polyneuropathy complex is guarded to poor. The condition is believed to be inherited.