Foal 'Stealing'

Q:We have a mare that is pretty far along in her pregnancy. I am not sure when she is due because when we bought her we had no idea she was pregnant. We also have another mare and colt that we rescued. To make a long story short, the pregnant mare thinks this 8-month-old colt is hers, and she will fight his mother and allow him to nurse off her. We have had to separate the three horses. She truly thinks this baby is hers and will go postal on anything in her way. Is it common for pregnant mares to adopt other mares' foals? What should we anticipate when she has her own foal?

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A: "Foal stealing," as it is called, is not as common in horses as it is in some other species. Textbook example cases typically involve a pregnant mare just about to foal, or a mare that has just foaled and lost her own foal. The explanation proposed (but not known for sure) for this in a mare just before she foals is that her hormones might be a bit misaligned, such that the hormones of bonding prevail a bit earlier than they should and maternal interest and bonding occur prematurely. So your mare is not exactly the textbook example, since it has been going on apparently for some time, and she still has not foaled herself.

When your mare has her own foal I'd expect that she will experience normal bonding with him. She might still look after the stolen foal if it is with her, and she might tolerate nursing by the stolen foal, but there should be diminished interest and concern for him in favor of the new foal, just as dams in nature do when they have a second foal with one still at their side. If you keep the 8-month-old foal separated from this mare, I would expect her concern to diminish within a few weeks.

About the Author

Sue McDonnell, PhD, Certified AAB

Sue M. McDonnell, PhD, is a certified applied animal behaviorist and the founding head of the equine behavior program at the University of Pennsylvania's School of Veterinary Medicine. She is also the author of numerous books and articles about horse behavior and management.

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