Diarrhea may be of bacterial, viral, parasitic or stress-related origin in the foal.
Call the veterinarian promptly as untreated diarrhea can be fatal to the horse due to the dehydration it causes.
The veterinarian will administer an intestinal dressing (coal) and infuse the horse to rehydrate if necessary. He will also try to determine the cause of the diarrhea in order to refine the treatment (antibiotherapy ...).
In the foal, it may be necessary to consider changing the mother's diet, suppressing milk in case of lactose intolerance, putting it under an infrared lamp to warm it up.