Abstract
Sera of pregnant mares were examined by the indirect anti-globulin test (TAT) to determine the presence or absence of erythrocyte isoantibodies (ETA). In mares with ETA, when their sera were tested against erythrocytes from their respective foals, 64.3% were TAT-positive. Throughout this study, foals from mares with E1A titers over 8 were not allowed to suckle colostrum . Foals were allowed free access to colostrum from mares whose ETA titer was less than 4. Sera of foals which did not suckle prior to 6-9 hours after birth did not contain detectable ETA. Generally, all foals were observed to have extremely low values for lymphocyte count, for counts and percentages of sIg-positive B lymphocyte (sIg-L), and counts of alphanaphthylacetate esterase (ANAE)-positive T lymphocyte (ANAE-L). Values all gradually increased, to reach normal adult levels by approximately three months of age. Only the sIg-L and the ANAE-L were significantly elevated in foals from ETA-positive dams. Progressive changes in ETA level followed three distinct patterns in sera and four different patterns in colostrum of mares. In mares with ETA-positive serum immediately prior to parturition and ETA in colostrum peaked 1-6 hours after foaling, a false negative test result in TAT of sera, to prognosticate the attack of neonatal hemolytic icterus, from the mares before 7 days of parturition were allowed.
