| Peripheral nerve and skeletal muscle from purebred Brown Swiss cattle affected with bovine progressive degenerative myeloencephalopathy (BPDME) were examined for morphologic and functional anomalies. The results of clinical neurology and clinical pathology evaluations were correlated with investigative findings resulting from necropsy, histochemistry, morphometry, muscle fiber typing, electroencephalography, electromyography, and both light and electron microscopy.;Clinical studies revealed progressive hind limb paresis, ataxia, dysmetria, and proprioceptive defects in affected test animals. Statistically significant differences were not detected between control and affected test groups for creatine kinase (CK), sorbitol dehydrogenase (SDH), lactate dehydrogenase (LDH), blood cholinesterase, plasma cholinesterase, liver selenium, liver copper, serum vitamin E, and the CSF parameters of CK, protein, and glucose.;Significant gross pathology was not observed in the selected skeletal muscles and peripheral nerves examined except for the mild to moderate skeletal muscle atrophy of the flexor and extensor groups of the coxofemoral and stifle joints. Light microscopic lesions were confined to peripheral nerves and included multifocal, segmental axonal and myelin degeneration within the sciatic, peroneal, tibial, and femoral nerves and their corresponding spinal nerve rootlets (L4 through S2).;Histochemical and morphometric analysis of selected skeletal muscles from the loin and pelvic limb did not reveal significant differences or pattern changes in the parameters of mean fiber cross sectional area and mean fiber type percentages.;Electrophysiological studies indicated a significant decrease in the sensory nerve conduction velocity in the left tibial, left peroneal, and right medial saphenous nerves of affected animals. Comparison of electromyographic and electroencephalographic findings between control and affected animals did not reveal consistent or significant data to support myopathic, neuropathic, or cerebral disease.;Peripheral nerves in affected test animals examined by transmission electron microscopy exhibited degenerative and reactive changes in myelin, axons, and schwann cells.;The pathological changes observed at the light and electron microscopic level were considered compatible with the "dying back" process and Wallerian degeneration. |
