What is IgG?

IgG stands for Immunoglobulin G and gives us an indication of the amount of antibodies in the foal’s blood that they have absorbed from the mare’s colostrum.

Why Test for IgG in Foals?

IgG testing can tell us if they have absorbed enough antibodies from the mare’s colostrum. The foal is only able to effectively absorb colostral antibodies in the first 8-16 hours of life. After this point, this is all the foal has to fight infections until their bodies start to produce their own antibodies at 3-4 months of age.

What happens if they don’t get enough colostrum?

This is called ‘failure of passive transfer’. The foal is then more susceptible to infection and does not have antibodies to fight infection if contracted. This can require veterinary intervention to ensure the foal’s survival. If we catch failure of passive transfer early, then we can provide antibodies in the form of intravenous plasma.

What do we recommend?

We recommend testing your foal at 8-12 hours of age. We can test them using a blood test on-farm and provide extra colostrum if required. The quality of the mare’s colostrum can also be tested immediately post-foaling. In foals older than 24 hours the IgG can be tested at a laboratory.