Sudden backing up when approaching a jump
I have a work-for-riding arrangement at a local barn and I really like the horse I work with. However, I only get him once a week. I am told he "knows how to jump," although the other rider who half leases doesn't jump much and lets him get away with it if he doesn't want to. We're talking popping over tiny logs and tiny crossrails, that's all.
Basically, about 30% of the time (usually in the beginning of our session) he pops over these little fences without batting an eye. He feels great, like he knows what he's doing, nice and relaxed.
But the rest of the time, as soon as he even THINKS we might be approaching a fence, he will suddenly start backing up violently. This might be well away from the fence, or even sometimes when We are just passing near one and he thinks we're going to go over, even if it wasn't my plan.
The two ways I've dealt with the problem are by popping up with a crop and insisting he go over, which can be quite a struggle and usually involves circling a few times. OR, when he starts to back up, I make him keep backing up alllll the way across the field so he realizes if he starts doing that it's going to mean more work of walking backwards for a long time. I always make sure to get him over it in the end, but it's often quite a struggle. The other ladies who ride with me have watched and say I'm not catching him in the mouth or hitting his back, or otherwise doing anything that might make him suddenly change his mind about jumping mid session.
Any idea why he jumps so nice the first couple of times, and then suddenly acts like he hates it after that?
And any other strategies for getting him to be more consistent? I know probably part of the problem is that I only ride him once a week, and I can't control what the other rider does, but surely there is something I can work on.