We had a pony mare spayed about twenty years ago. This procedure only cost $75 at the time, but I'm sure it is closer to $300 to have it done now. It worked. The pony mare somehow developed a better attitude. The vet was laughing and said he had spayed a mare for his brother a few years before. That mare's attitude seemed to get better, but a couple years later his brother was complaining that she was back to being a rip. He joking asked the vet, "Can we spay her again?"