Neurological disease associated with degenerative axonopathy of neonatal Holstein-Friesian calves.

The clinical and pathological features of 19 neonatal Holstein-Friesian calves affected with moderate to severe neurological disease are presented. Most calves were recumbent from birth, and many developed variable neurological signs including hyperaesthesia or depression, limb extension, head tremor, nystagmus, apparent blindness, and opisthotonos when stimulated. Consistent lesions of moderate to severe, diffuse, axonal swelling and loss, with Wallerian-type degeneration and myelin depletion in the spinal cord and brainstem, and occasionally in the midbrain and peripheral nerve roots, were observed. The lesions indicated a pre-natal insult affecting mainly motor areas of the foetal neuraxis, however the aetiology of the disorder remains undetermined. It is suggested that the calves may have been affected by a hitherto unrecognised disease entity for which we propose the term, degenerative axonopathy.