Well, there's always the old-fashioned way to get rid of heats for a while.
Have her bred.
*smiling to myself thinking of a mini-Cyn running around*
Oh yeah - that's just what we need! Another small horse without a job around the place!
Heh... I'd like for ecurbh and I do go through a birth sometime... someone else's birth that is... So you never know, we may hit her up. I'd want to breed for a little more size and bulk than she has... either a Quarter Horse (that would produce an unregistered grade foal) or a big Polish Arab of Bay's size and heft (that would produce a registerable foal). I'm hesitant about trying to breed size into a small mare, although I'm told foals don't grow too big in the womb, I'd think they might have a harder time bred to a stallion larger than themselves. Thoughts anyone?