I can get her to walk and trot fine with my voice, but she won't canter at all. I never canter her when I'm driving her, so she doesn't know any voice commands for that gait. How would I go about teaching it to her?
If it matters at all, she's a Percheron (maybe TB cross?), about 16 years old, and is very calm and will do whatever you want her to as long as she knows what it is that you want her to do, obviously.