Immunity in foals

At birth, foals are immuno-naive meaning that they are born without any protective antibodies (immunoglobulins/IgG) against common ‘bugs’ in their environment.

In order to gain protection, foals need to ingest a sufficient quantity of good quality colostrum (first milk containing high levels of antibodies) within the first 12 hours of life.

It is during this time that foals have maximal absorption of ingested IgG. After this time, absorption rapidly decreases.

Adequate IgG levels are crucial to protect foals from developing infections (namely sepsis). Inadequate levels result from failure to ingest sufficient quantities of colostrum or poor quality colostrum (e.g. when the mare runs milk before birth and loses IgG).

To determine that foals have adequate IgG levels, we recommend measuring IgG using a simple blood test, generally 18-24 hours following birth.

If levels are inadequate then a hyperimmune plasma transfusion is recommended to provide the foal with IgG and in turn protect the foal from developing life threatening infections.

Image source: foalpatrol.com