Originally Posted by FoxyRoxy1507
my horse used to do this and i've had many others as well, what I would do is wait till we would get to a corner at a nice rounded trot and very slow so he's really sitting on his hind end and then ask for the canter but lift ur inside right hand up about two inches so it forces him to lean back more. This will help him to be more balanced and his head will be up so that he cannot buck and really get him to understand that you want him to pick up the right lead. Eventually you can use this technique on straighaways and then you wont even need to lift ur hand after more practice.
This is pretty much what I did with my horse. When I first got him he didn't know how to pick up his left lead canter.. what I had to do with him was bend him (not so much that you overbend, though), and ask for it in a corner when he's already bending. Have an energetic but not rushed trot. As Roxy said, pick up your leading hand about two inches (eventually this won't be necessary); it helps to shorten that rein before you ask as well. Sit tall and shift your weight to your outside hip; you might have to sit a bit behind the vertical in the early stages of teaching his lead. If he gets the wrong lead, simply bring him back to the trot, reorganize, and ask again in the next corner. Use tons of inside bend leg. Today my horse picks up his lead entirely off leg and seat, and with barely any signal. He learned within about 3-4 months, on estimate. If he appears to be in pain, I would definitely recommend getting him checked by a chiropractor.
Before you do canter work, try lots of bending circles to the right, and lots of walk/trot transitions. These both will help balance him up and prepare him for cantering. He may be really stiff to the right, which is one of the things that happened with my horse, and that just takes time and patience to work out.