Studies on viral leukoencephalomyelitis and swayback in goats.

Six kid goats with CNS disease were studied by a variety of techniques. All had morphological evidence of Viral Leukoencephalomyelitis of Goats. (VLG) characterized by demyelinating encephalomyelitis and pneumonitis. Attempts were made to isolate a virus from 5 of these goats by direct culture of CNS and visceral tissues. Syncytial formation was found in some lung, spleen and bone marrow cultures but syncytia were found to be free of complete virus by electron microscopy. When newborn goats were inoculated with syncytia forming cells, a visna-like virus was found in bone marrow cultures of 1 goat 8 days post inoculation. Bone marrow cells from a twin goat 3 months after inoculation produced syncytia without complete virus. it is suggested that complete virus might be present in goats shortly after infection, while persisting in an incomplete form. Three of the 6 goats studied also had lesions of swayback with diffuse encephalomyelopathy and low liver copper levels. Control copper levels in kids with non-neurological disease were variable, occasionally being as low as swayback animals. The experience of others that swayback in the goat and low copper status are poorly correlated is confirmed. Discrepancies inherent in assaying formalin preserved tissues for copper are described.