“Mares… had not been altered, in them the blood flowed freely, their life cycles had not been tampered with, their natures were completely their own. The mares usually had more energy than the geldings, could be as temperamental as the stallion and was, in fact, its superior.” John Hawkes – Whistlejacket
Personally, I think mares tend to get a bum rap.
Ruffian, coming down the stretch
There have been lots of great mares. At almost 17 hands tall and jet black, Ruffian is considered by just about everyone to have been one of the greatest racehorses of any gender that has ever lived. Ruffian made a total of 11 lifetime starts, winning all but her final, and ultimately fatal, match race against 1975 Kentucky Derby winner Foolish Pleasure.
Touch of Class
Touch of Class, a bay Thoroughbred mare, was only 16 hands tall, yet she posted the first double clear rounds in Olympic show jumping history. She took home two Gold Medals from the 1984 Olympics (where it was rumored that the oxers were larger then her stall). The little mare could really jump!
Sarah
And, of course, one can use the word “great” in many contexts. Sarah is a 30 year-old Quarterhorse mare who has happily carried her owner over fences, across creeks, through deserts, and around traffic for 17 years (depending on where she was stabled). Over the years, she’s won ribbons, and hearts. Sarah’s pretty great by any definition, although she hasn’t gotten any publicity (until now).
Lisa Simpson and Princess
Lisa Simpson has a pony – her name is Princess.
Of course, there’s also the old grey mare, but she ain’t what she used to be.
So, given that there are, and have been, so many great mares, why is it that so many people seem to be reluctant to keep them? In my opinion, it mostly boils down to one thing – mares come into heat.
Like most mammalian species, mares are looking to keep their species alive. When mares are in heat, they can be pretty obvious about it, because they are looking to get bred. In fact, some mares, when in heat, do give some rather obvious – and to their owner’s: embarrassing – displays of the fact that they are in heat. And other horses may notice, too!
Now it’s a fact that women get accused of being moody during their reproductive cycles, too. For example, a woman 
who is having emotional swings may be said – in something of a knee-jerk reaction – to have PMS (and much worse). It’s pretty much set in peoples’ minds that reproductive cycle changes = mood and behavioral changes. So, since they’ve pretty much set in their mind that women have emotional swings as a result of their reproductive cycles, when people grumble and generalize about moodiness and behavioral changes and erratic performance of mares they always have the explanation for it: “She must be in heat!” The fact is that many times a mare’s poor behavior or performance has nothing to do with her reproductive cycle at all – horse moods, like people moods, can vary from day to day.
Still, because mares do come into heat, and because – rightly or wrongly – their behavior on any particular day tends to get associated with their reproductive cycle, trying to keep mares from coming into heat has turned into something of an obsession, particularly for owners of performance horses. Folks try to keep mares from coming into heat in any number of ways, some of which work, and many of which don’t (but still get used). It’s a closet industry, of sorts.
Before you can try to control the mare’s heat (estrous) cycle, you sort of have to understand the mare’s heat cycles, so let’s briefly talk about it. The normal mare’s cycle is 21 – 22 days long. It’s made up of two parts – diestrus, the approximately 15 day period when the mare isn’t showing signs of heat, and estrus (heat), the 5 – 7 day period that some horse owner’s apparently fear.
The mare’s cycle is influenced by various hormones. Hormones are regulatory substances; they are usually produced in one spot, and then transported in tissue fluids (such as blood) to a target tissue, where they stimulate specific cells or tissues into action. When the mare is in diestrus – when she doesn’t show signs of heat – the hormone that has the most influence is called progesterone. When there’s lots of progesterone in the mare’s bloodstream, the mare’s not in heat. And that’s the point of most of the therapies that are out there – they try to increase the level of progesterone, in one way, or another.
Mares are (mostly) great. But if you’re worried about her heat cycle, and you want to try to control it, it seems to me that you should use something that actually works. Part 2 is going to talk about many of the different treatments that people use to try to keep their mare’s heat cycle under control.
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