As mentioned in our last program, foals derive all of their antibodies to fight infection from the mare’s first milk, or colostrum.  Absorption can occur only in the first 24 hours after birth.  For this reason, it is imperative to know that the transfer of antibodies from the mare to foal occurred. Even if the foal is nursing that does not guarantee sufficient transfer of antibodies.  Failure of passive transfer can occur for several reasons.  Reasons for failure of passive transfer by the mare are inadequate antibodies, or IGG, that are present in the colostrum, leaking of colostrum from the udder prior to foaling, inadequate let-down of milk or lack of milk production, and acute illness of the mare.  Problems preventing the foal from getting the antibodies from the mare are if the foal is premature , weak, sick, has a congenital abnormality such as a cleft palate, or the small intestine fails to absorb the colostrum.  Maximum absorption of antibodies occurs immediately after birth and decreases rapidly over a 24 hour period. 

Therefore, a normal foal should be up by 2 hours and nursing by 4 hours.  All foals should be examined by your vet and blood tested at 10 to 12 hours for the amount of antibodies present.  If the level of IGG is less than 400 mg/dl, the mare should be milked and the foal fed with a nasogastric tube if it is not nursing, or the colostrum should be checked for quality if the foal has been nursing well.  If the mare’s colostrum is found to be inadequate, the foal may be given frozen colostrum if that is available.  There are some commercial oral products available that claim to raise the IGG levels if given within 12 hours of birth.  However, some of these products have not been proven effective in scientific studies.  If the IGG concentration is less than 400 after 24 hours, intravenous plasma is usually required to treat these foals.  Ideally, I like to see the IGG concentrations in foals over 800 mg/dl.  This is critical for the foal’s survival.