Other than David and I, Raven is the only resident of Farcical Farm who remains reproductively intact. I don't consider her to be of breeding quality (despite a reasonable pedigree) and I have no interest in contributing to North America's glut of unwanted horses. Furthermore, Miss Thing can be a real wench when she's in heat -- our neighbors report that she beat the crap out of Tonka today for no particular reason.
Spaying mares is uncommon, mostly because traditional methods are invasive, expensive, time-consuming and prone to disastrous complications. One procedure involves removing the ovaries through the belly under a general anesthetic. The recovery period is about 12 weeks. Another procedure involves removing the ovaries through the flanks, which can be done under the influence of a tranquilizer in standing stocks. The recovery period is about 6 weeks.
The more modern procedures involve severing or tying off the ovaries by way of the vaginal cavity. If her care-givers are careful during the first 48 hours (to ensure that no intestinal material herniates through the incisions) the mare can be back at work within two weeks. At this stage it's just a question to ask Kerstin the next time I see her. I have no idea whether spaying Raven is financially practical or physically feasible, but until yesterday I didn't even know that it was possible.