Colostral and foal serum immunoglobulin G levels and associations with perinatal abnormalities in heavy draft horses in Japan

The purpose of this study was to elucidate the colostral and foal serum immunoglobulin G (IgG) concentration values in heavy draft horses in Japan and to examine the effects of peripartum mare condition on colostral immunity. Colostrum was obtained 1 hr after foaling (pre-suckling; n=178). Blood was collected from the jugular vein of the foals (n=147) at 24 to 48 hr after birth. The foaling statuses of 73 mares were recorded. The average colostral IgG concentration was 10,540 ± 3,190 mg/dl (median=10,928; range 1,434-17,514 mg/dl). The average serum IgG concentration obtained from neonatal foals 24 to 48 hr after birth was 1,750 ± 919 mg/dl (median=1,890; range 0-3,510 mg/dl). Although colostral IgG did not differ between the normal foaling mare (n=59) and dystocial mare (n=14), foal serum IgG was lower in foals born in dystocia than in foals in normal foaling (P<0.05). This study demonstrates reference values for colostral and foal serum IgG specific to heavy draft horses in Japan and suggests that dystocia may interfere with the acquisition of colostral immunity in neonatal foals.