Abstract
Two 6-week-old female Rottweiler littermates were evaluated for regurgitation, diminished growth, progressive ataxia, and pelvic limb weakness. Clinical examination indicated a progressive, diffuse, lower motor neuron disorder and megaesophagus. The pups were killed at 6 and 8 weeks of age. Lesions included central chromatolysis and swelling of the perikarya in many large motor neurons in the ventral gray matter of the spinal cord. Some involvement of red, oculomotor, trigeminal motor, and ambiguus nuclei of the brainstem was noted. Ultrastructurally, chromatolytic neurons had excess neurofilaments, and an increase in and enlargement of Golgi complexes. Wallerian-like degeneration was prominent in neuropil of spinal cord and in peripheral nerve. Clinical, histological, and ultrastructural findings were consistent with a progressive motor neuron disease.