Calming Mother Nature

Q: I have a 7-year-old Quarter Horse mare that is quite "the mare." When she is around the geldings (even if they are in different pastures) and in season, she will put her butt up to the fence and wink (the vulvar lips), etc. She gets the geldings completely in a dither. The 5-year-old Thoroughbred tries to mount her, and she allows it. The 15-year-old Quarter Horse gelding will drop down (his penis). The 6-year-old Quarter Horse gelding bites her and tries to mount.

I need some help in trying to resolve how to bring this mare down a few pegs when she is in season. She is really a very good horse when she is not in season. If she is in season, she won't lift her tail to pee, she lets it run down her legs. We have to fight "pee rot" all spring and summer till she stops coming into season. I really do need some help.              via e-mail

A:This is a tough practical problem to address because even though it's annoying, your mare and your geldings are just showing normal horse behavior, exactly what Mother Nature intended. For those geldings that retain interest in mares, there is really not too much to do except keep them far away from mares. On the mare side of things, often the easiest approach also is to just keep the mare housed away from males.

Having said that, there are some ways you can attempt keeping a mare from having cycles of estrus and ovulation. These include such treatments as progesterone that can inhibit estrus and even sometimes stop ovulation, or intrauterine marbles that can interfere with the ovulatory cycle and, thus, eliminate estrus (search #4189 at These approaches work well in some mares and not at all in others, and it is not easy to predict which mares will respond or at what dose of progesterone, for example, estrus will be suppressed. So it has to be a trial-and-error approach.

Removing a mare's ovaries (spaying) so that she no longer cycles during the spring and summer is not as straightforward as in other species. In the mare, spaying can lead to her showing estrus in a mild form all of the time. This is because in the mare it is the production of progesterone by the ovary that turns off the estrous behavior. So while the estrus might not be as strong in a mare without ovaries, it can be there all the time. In mares such as yours it is not uncommon for them to still respond to males as if in estrus, even after they are spayed.

I'm curious about the problem you mention with your mare not lifting her tail when urinating. Most mares during estrus do not clamp their tail and significantly soil and scald their legs. Rather, when voluntarily approaching males and teasing at liberty, mares normally lift the tail off to the side and position their legs so as not to be soiled. In windy conditions, if free to move, they often even appear to orient in a manner that avoids soiling their legs. This makes me wonder why she is clamping her tail, or if there is some physical problem that is causing the urine scalding. I would suggest an examination by an equine theriogenologist (reproduction specialist) to be sure the mare has no physiological problems with her perineal area.

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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