by Casie Bazay Collaborator

Foal Heat in Horses: How to Protect the Newborn Foal

Foal Heat in Horses: How to Protect the Newborn Foal

Breeding on Foal Heat

Foal heat is what we call the first estrus or mare heat cycle after foaling, and it usually begins 6-8 days after foaling with the first ovulation occurring 10 days postpartum, on average. Many breeders choose to breed their mares back during foal heat in an effort to maintain a 12-month foaling interval. 

While this works well for many mares, conception rates are typically higher in mares with relatively later as opposed to earlier foal heats (likely related to uterine healing), and it should be noted that mares turned out on pasture tend to have quicker uterine recovery rates than mares kept stalled after foaling. Additionally, a younger mare is more likely to conceive during foal heat and also less likely to lose the pregnancy than an older mare.

Some mares may not be physically ready to breed or may have poor conception rates if bred during foal heat, especially if the mare experienced a difficult birth or retained placenta. In these cases, she may have inflammation, infection, or fluid accumulation in the uterus. It should also be noted that some mares giving birth in very early spring may not have a foal heat, but instead have their first post-foaling heat approximately 30 days later (before resuming a 21-day cycle). 

How Long Does Foal Heat Diarrhea Last?

One complication which often coincides with a mare’s foal heat is a bout of diarrhea in the newborn, known as ‘foal heat diarrhea’. While originally thought to be caused by hormones produced by the mare’s body during their first estrous cycle after foaling, many veterinarians now believe this gut disruption in foals may be caused by normal but rapid changes in the bacterial and protozoal population in the gut. Foal heat diarrhea also occurs around the same time that foals begin to nibble on the mare’s manure, as well as eat small amounts of hay or grain, so these may all be contributing factors as well. 

While foal heat diarrhea is usually a mild occurrence, it’s important to monitor your newborn closely to ensure the condition does not worsen. Applying a topical protectant such as petroleum jelly or zinc oxide to the skin around the anus and rear end can help prevent scalding of the area, and administering probiotics specifically designed for foals, such as the FullBucket Foal Probiotic Paste, may also help combat diarrhea. 

In fact, supplementing with probiotics during your foal’s first few months can help to ensure the early establishment of a healthy gut microbiome. 

Keep in mind that not all diarrhea occurring in foals is necessarily normal. If your foal experiences severe diarrhea lasting more than a few days, has an elevated temperature (above 101.5 degrees F or 38.6 degrees C), or is not nursing regularly, you should consult with your veterinarian right away, as a bacterial infection may be present and will likely need treatment. 


Knowing what’s normal during your mare’s foal heat and understanding foal heat diarrhea, as well as how to manage it, will help ensure that the postpartum period goes smoothly for your mare and foal. 



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