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Foal Immune System – IgG and Plasma

We would normally expect a newborn foal to stand within 1 hour after birth, and it should be nursing within 2 hours of its birth. The mare’s “first milk” (colostrum), contains a rich mix of the antibodies a newborn foal needs to develop a healthy immune system of its own.

There are times when the newborn foal does not nurse adequately, or the mare does not produce enough colostrum. We want to give every foal the best possible start in life, so we strongly recommend running an IgG (Immunoglobulin G) test approximately 12 to 18 hours after its birth.

The purpose of the IgG test is to check the foal’s blood for “Failure of Passive Transfer” (FPT). FPT occurs when the antibodies are not transferred from the mare to the foal via the mare’s colostrum. The most common causes of FPT are poor quality mare’s colostrum and premature lactation.

An IgG test is done right there in your barn, and accurate results are available in just a few minutes. Ideally, the foal should be 12 to 18 hours old when we draw the blood sample. At that stage, his/her IgG (antibody) level should be greater than 800mg/dl to be considered adequate. An IgG less than 400mg/dl indicates Failure of Passive Transfer. If the IgG level is between 400 and 800mg/dl, there was a partial failure of transferred immunity.

What do we do if Failure of Passive Transfer (FPT) does occur? Supplementation is provided in the form of intravenous plasma. The foal is lightly sedated and rests quietly on the ground with a loose cloth over both eyes for protection. The mare generally stands nearby or within eyesight of her baby. An I.V. catheter is placed and the plasma is administered. When the foal wakes up, he/she is reunited with the mare. The foal’s immune system is now super-charged and ready to fight off potentially deadly pathogens.

A new trend in equine breeding standards is emerging. Newborn foals are given I.V. plasma regardless of actual need for IgG supplementation. Breeders consider the added protection well worth the relatively low cost of the procedure.

Fox Valley Equine Practice keeps frozen plasma in stock during foaling season as part of our commitment to providing “The Best Medicine in the Field”. If you would like more information about this subject, please drop us a line or give us a call.