How to Recognize Critical Illness in Foals

lining and immune system occur in the hours after birth and are critical to the foals survival. The urachus the channel between the bladder and umbilicus is normally closed at birth so urine starts flowing through the appropriate pathway. The intestinal lining or epithelium remains very porous during the first six to eight hours of life to allow absorption of some very large molecules called antibodies ingested in the first milk or colostrum. These antibodies provide the foal with immunity from bacteria viruses and other potentially lifethreatening infectious diseases. This passive immunity is essential for the life of the foal until his immune system matures and he is capable of making his own antibodies through active immunity at about six months of age. For this reason foals are not routinely vaccinated for most diseases before about six months as they may not be capable of producing an immune response to vaccines. If the mare is vaccinated about 30 days prior to her due date she will pass the immunity on to her foal when he nurses the colostrum during his first day of life. 
Fortunately things proceed normally almost all of the time. Foals have survived the cold cruel world much longer than there have been foalwatch teams to worry about them. That being said how do we know when things are not right? What are the signs? What can and should be done? In order to understand how things can go wrong it is important to review the normal physiological processes taking place around the time of birth. 
When the foal is still in utero he does not breathe or eat. Oxygen and nutrients in the mares blood are transferred directly to the blood supply of the developing fetus through an elaborate system of membranes called the placenta which is attached to the foal through his belly button or umbilicus via the umbilical cord. Waste products from the foals blood are then transferred back across the placenta to the mares blood to be eliminated. Shunts in the fetal foals circulatory system serve as little detours which direct blood away from the lungs and liver as these organs are not needed until the beginning of life on the outside. Immediately after birth since the foal can no longer rely on his mother for oxygen nutrients and waste elimination these shunts must change to allow normal function of all body systems.
Cardiovascular
and respiratory heart blood vessels and lungs changes occur first and the blood is instantly directed to flow through the lungs so they can inflate absorb oxygen and expel carbon dioxide. Other changes involving the liver urinary bladder intestinal lining and immune system occur in the hours after birth and are critical to the foals survival. The urachus the channel between the bladder and umbilicus is normally closed at birth so urine starts flowing through the appropriate pathway. The intestinal lining or epithelium remains very porous during the first six to eight hours of life to allow absorption of some very large molecules called antibodies ingested in the first milk or colostrum. These antibodies provide the foal with immunity from bacteria viruses and other potentially lifethreatening infectious diseases. This passive immunity is essential for the life of the foal until his immune system matures and he is capable of making his own antibodies through active immunity at about six months of age. For this reason foals are not routinely vaccinated for most diseases before about six months as they may not be capable of producing an immune response to vaccines. If the mare is vaccinated about 30 days prior to her due date she will pass the immunity on to her foal when he nurses the colostrum during his first day of life.