Infectious diarrheas are common in young foals and severity of the disease varies from mild to deadly. Some of these diarrheas are due to so-called blood poisoning or an infection in the blood. Many of these infections develop from an umbilical infection or bacteria absorbed through the stomach lining. Dr. Sam Jones from North Carolina State indicates foals have an open stomach during the first 24 hours of age so that they can absorb the large molecules of antibodies in the mare's milk. However, they can also absorb bacteria at the same time. If the udder is dirty or the foal is in a dirty environment, they ingest a lot of bacteria.

For this reason, it is a good idea to clean the mare's udder before the foal nurses. Also, if you can milk out a pint of milk from the mare and give it to the foal with a bottle before nursing, the gut will start closing and they will absorb fewer bacteria. You also can give the foal antibiotics for 3 days to help kill any bacteria they may have absorbed. Salmonella is one cause that can develop into diarrhea because some mares shed salmonella because of the stress of foaling. Two other bacteria that can cause diarrhea in young foals are clostridial strains. These clostridium bacteria produce bloody diarrhea and also produce toxins or poisons that can cause shock and lead to death. Rotavirus is the most common viral cause of diarrhea in foals and usually causes a watery diarrhea. Although these foals can be sick, they are usually not as sick as foals with bacterial infection. If you have a foal that has diarrhea and is depressed, consult your vet quickly as these foals can die in a matter of hours.