Degenerative myeloencephalopathy in two llamas.

Degenerative myeloencephalopathy of unknown cause was diagnosed in 2 mature llamas. One llama had ataxia and paresis of the left limbs; whereas, the other developed tetraplegia that was not preceded by obvious ataxia or paresis. Results of cranial nerve examinations were unremarkable in both llamas. Cerebrospinal fluid from both llamas was normal, and hematologic and serum biochemical abnormalities were attributed to concurrent conditions and not to the myeloencephalopathy. Results of cervical spinal radiography and myelography in 1 llama were normal. In each llama, the diagnosis of degenerative myeloencephalopathy was made at necropsy after the llama failed to respond to treatment for other neurologic or muscular disorders. Lesions of degenerative myelopathy were found bilaterally in the white matter of all spinal cord segments, but were most pronounced in the thoracic segments. The dorsal and dorsolateral funiculi were most severely affected. The most prominent lesion was axonal sheath dilatation, with swelling or loss of axons. Dilated axon sheaths contained cellular and myelin debris, and accumulation of gitter cells was prominent. In the gray matter of 1 llama, a few degenerate neuronal cell bodies were seen in addition to axonal swelling. Degenerate neurons were identified in the brain stem of both llamas.