Hemolytic disease of the newborn, also known as neonatal isoerythrolysis (NI), is a serious problem in newborn foals whose red cell type is incompatible with their dams’. A foal which inherits a red cell factor from its sire that the dam does not possess, is at risk for this condition which results in the destruction of the foal’s red cells after the foal is born and nurses the mare’s colostrum. There is no in utero effect, since the antibodies against the foal’s red cells cannot cross the placenta. However, the colostrum is rich in antibodies, and in mares that are sensitized to a red cell factor, the colostrum can be deadly instead of protective. The Blood Typing lab offers a serum screening service for mares with a history of NI. A serum sample is submitted within 30 days prior to the mare’s due date.  If antibody levels to one of several “high risk” factors are elevated, it is essential to prevent the foal from nursing its dam's colostrum, and provide it with a substitute colostrum. In addition, mares with a known history of NI can be crossmatched to a stallion that does not have the red cell factor to which the mare has become sensitized. That way, the foal cannot inherit the factor from the sire, and will not be susceptible to the mare’s antibodies.

Our NI testing program can prevent this problem by:  

  • crossmatching stallion and mare blood types or
  • testing serum from the mare 30 or less days before foaling