Foal Diarrhea Part 2: Foal Heat Diarrhea
As previously discussed, diarrhea in young foals can range from a messy inconvenience to a rapidly life-threatening condition. A very common but fortunately relatively harmless cause is a syndrome called foal heat diarrhea, so named because it usually occurs around the time of the mare's first heat after foaling, when the foal is about 7-10 days old. Foals with foal heat diarrhea have diarrhea but no other problems like weakness, decreased appetite, colic or fever. If any of these other signs are present, then the foal has something other than (or in addition to) foal heat diarrhea.
The cause of foal heat diarrhea is not known. It doesn't actually have anything to do with the mare's heat, or the mare at all in fact - it even occurs in foals that are bottle raised and have no contact with a mare. It's likely the result of normal changes in the bacterial microflora in the intestinal tract of the foal that just happens to occur at this age.
Foals are usually diagnosed with foal heat diarrhea when they are the right age and have mild diarrhea but no other problems. Testing for (and ruling out) other causes of diarrhea like salmonellosis helps to support this diagnosis.
Any foal with diarrhea must be monitored closely for developing signs of illness. Don't fall into the trap of simply chalking up a diarrhea episode to foal heat diarrhea and forgetting about it. If you're wrong, a foal with diarrhea due to an infectious cause can go from looking "okay" to too weak to stand and nurse (or worse) within a matter of hours.
Foal heat diarrhea does not require any treatment in almost all cases. Occasionally, foals can get weak or dehydrated if they don't drink enough to make up for the fluid lost in the diarrhea, but this is quite rare. Foals almost always get better on their own. If they don't, there is probably something else going on and diagnostic testing is needed to determine what that is.
The fact that foal heat diarrhea gets better on its own may be one reason there are so many "proven" foal diarrhea treatments by which people swear. Some people are convinced that certain treatments are highly effective because when they treat foals, they get better. However, with foal heat diarrhea, which is probably the most common cause of diarrhea in foals, the animals get better regardless of (or despite) what you do. That's why well-designed research trials that include untreated control groups are needed to determine if treatments actually work.
