Overview of Diarrheal Diseases in Foals

Diarrhea in foals can result from overfeeding (eg, when a foal is reunited with the mare after a period of separation) and improper nutrition (eg, orphan foals being fed calf milk replacer or sucrose). Lactose intolerance in foals is rare and can be determined by lactose tolerance challenge tests or clinical response to supplemental lactase. Diarrhea can also develop when foals consume indigestible substances such as roughage, sand, dirt, and rocks. Diarrhea in foals has been reported to be associated with infection by Strongyloides westeri, Parascaris equorum, and Cryptosporidium spp. (Also see Gastrointestinal Parasites of Horses.)