Horse is very forward going and gets very excited in canter.
Horse is bitless doesn't use bits.
Running or standard martingale
Check everything with dentist/vet/physio, keep the Horse moving forward and maybe add in a bit of difference in the canter like pole work 94 using the half halts like mentioned, sometimes throwing of the head can be an evasion other times they’re telling you somethings not right
Make sure he is moving into the contact from behind
You could try using little half halts (small squeezes on the reins) to keep him focused and to busy to throw his head. You might also try using a softer contact.
I would check their teeth
make sure all tack fits correctly & that you are going with the motion
Could try a standard martingale 👌🏼