Originally Posted by SA Trail Rider View Post
The horse was taken out of the veld and backed last year so no prior handling. He may have been abused by the trainer
A horse doesn't have to be 'abused' to have a mental/emotional problem with something. It could be that there were things that were neglected or overlooked in initial training, so he had issues with lack of understanding, trust, experience, etc. It could also be that you maybe didn't recognise his subtle signs & overlooked or took stuff for granted yourself, that perhaps showday was just the 'final straw' when he felt the need to make it blatantly obvious & following experiences have reinforced association between the Bad Thing with turning one direction... lots of speculation & it could be purely behavioural, but IME this isn't so likely & I'd at least want to conclusively rule out physical issues first.
I checked every piece of tack that could be causing the problem and nothing was. He had his teeth done recently and he was still the same. He had his hooves done recently too.
That's a really good start. How did you check the tack, particularly the saddle for fit? Balance International is one website to look up with great info on saddle fit, design, common issues due to ill fitting, if you need more info in that regard. On the saddle possibility, he could also have had problems due to an overtightened girth, your weight or balance combined with the saddle's weight or balance, etc.
If you ride with a bit, horses can have problems with them for various reasons aside from bad teeth too. Likewise with hooves/legs, etc. While regular good hoofcare is indeed important, it isn't the only thing that may affect soundness by far and it's also possible he wasn't *well* trimmed. There are also a multitude of other physical problems that we could speculate about, but getting a good equine vet out to check him would be a good start.
I would be staying off this horse's back until the problem has been resolved, or you've at least worked out that it's nothing physical.