Clinical, magnetic resonance imaging and histopathological findings of a congenital hypomyelinating leukodystrophy in a Holstein Friesian calf

A 12‐day‐old, male Holstein Friesian calf was presented to the hospital due to progressive ataxia and tremors since birth. A diffuse central nervous system disorder primarily affecting white matter was suspected based on clinical neurological examination. Blood tests were unremarkable, except for positive serology for Schmallenberg virus. Magnetic resonance imaging of the brain demonstrated severe, diffuse abnormalities primarily affecting the white matter regions of the encephalon and cranial cervical spinal cord, consistent with leukoencephalomyelopathy. Euthanasia was performed at 8 weeks of age after no clinical improvement. A postmortem examination was performed. Histopathological examination of the central nervous system revealed changes compatible with hypomyelinating leukodystrophy, with no signs of infectious agents observed. The disorder was considered most likely to be hereditary, as Schmallenberg virus infections during pregnancy in cattle have not been reported to result in such clinical, magnetic resonance imaging or histopathological findings, and no viral genomic material was identified with polymerase chain reaction.