Science Sunday; Why Are Foals Susceptible To Diseases?

New born foals are particularly susceptible to disease as they rely on colostrum from the mare to give them antibodies. Colostrum is the first bit of milk they get from their mother and is important as it contains antibodies developed by the mare that are a response to the immediate environment. The mare therefore has to be in the environment that the foal will be born into 2-3 weeks before so that the antibodies made will be specific to the correct environment. These antibodies allow the foal to fight infection before its immune system becomes efficient. The new born foal is able to absorb these antibodies through the intestinal wall and into the blood stream. The ability to absorb these antibodies only lasts for the about 12 -24 hours. During this period the foal needs to have 1- 2 litres of colostrums. These antibodies protect the foal for the first 2-4 months of life. After this, the foals own immune system becomes more efficient making its own antibodies. If the mare leaks colostrum, it will be lost so there will not be enough for the foal.

A number of conditions in the foal are a consequence of them not receiving enough colostrum, leading to a failure of them receiving this early immunity. This could be due to the foal being born premature or the mare running colostrum before parturition. There could be a reduced quality of colostrums that contains low antibody levels. The foals access to colostrum could also be reduced, such as the foal being separated from the mare of the foal being too weak to feed in the early hours after birth. The foals immunity levels and the quality of the colostrums can be checked in a number of ways to see if there are any problems.

These problems could be prevented by giving the foal colostrum supplementation, this is useful within the first 24 hours of birth. There are a number of types of antibodies and if it is given after this time the IgM antibody will still be absorbed but the IgG may not be. It may be possible to create a colostrum bank by milking the colostrum from a number of different mares after the foal ahs had enough, this can be stored in the freezer and mixed together and can be given to sick foals when they need it.

A plasma transfusion may be given if there are severe problems, this is when 3-4 litres of blood is taken from a donor mare or gelding. The plasma is separated from the blood. This can then be transfused into a foal and will raise their IgG antibody levels.

Love Laura
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