Border disease of sheep: spinal cord morphometry

Semi-automated planimetry was used to determine cross-sectional areas of spinal grey and white matter by direct microscopy of paraffin sections of spinal cord from Border disease (BD) and normal lambs at segments C4, C8, T6 and L4. Spinal cord cross-sectional area was significantly reduced in cases of BD produced by either intramuscular or intranasal inoculation of ewes in the first half of pregnancy with Weybridge strains of BD virus. The reduction was apparent at all 4 levels and in both grey and white matter, though the white matter was the more severely affected. Spinal cord areas tended to be smaller in the progeny of ewes exposed earlier in gestation or to larger doses of virus, but these differences were not statistically significant.