Need non-jumping exercises to help a 6 year old TB that tends to get a bit unbalanced after a fence. Either goes on forehand and/or speeds up after jumping a fence. Seems to happen when he meets a fence long or on a half stride. Combinations and lines are tricky too. Thinking this is a hole in flat work where he is fussy in his canter walk or halt transitions. He is a bit of a snowflake and gets offended at the downward transitions if you are not tactful. He is in a happy mouth bit and has the best care available, even had the vet out to make sure it wasn’t a pain issue. Looking for the sage advice of the forum to give me some exercises to help him with downward transitions as well as pole work to help him with his jumping? Thank you in advance!
Cantering cavaletti can be extremely helpful; used judiciously and correctly, the work will result in an improved canter with more jump and ability to compress and rock back. Obviously doing “transitions within the gait” (and some spiraling in and out) will also help his canter become stronger and more adjustable.
I start with poles on the ground about 9-10 feet apart, and then progress to slightly raised cavaletti - you can move them closer together as the horse gains strength over time. Start with one, then go to two, then finally 3 - on a curved line - this helps you put the horse on the outside rein. You can work on balancing the canter on approach to the poles/cavaletti (maintain the rhythm by counting) and then when you get the round, balanced, “jumping” canter that carries you over the poles, keep your leg ON and stay soft with your seat, engage your core, half halt, and gear down to trot afterwards. Stay SOFT and following with your rein over the cavaletti; you are trying to encourage him to jump through his body and use his head and neck, not brace against the hand. The canter should feel elastic.
The goal will be to help your horse find the base more often and jump more comfortably from it - even if he gets there on a half stride. When he is able to softly compress his canter stride in balance (before the jump), he will “pat the ground” in front of the fence while rocking back, rather than either launching or throwing in an awkward chip. He should maintain impulsion to the jump without speed/flatness. It comes from strengthening his core and hindquarters so he doesn’t “lean” at the jump and tip onto the forehand.
Obviously gymnastics (with placing poles) will help him too 
Bounces are good for this.
Have you tried circling right after the jump, or halting? I have used a balance/neck rope to help rock my horse back (while using my core to WHOA) since I need WAY less rein that way - something that your boy may find less “offensive.” 
In lessons with Stephen Bradley, we worked on this tendency in my headstrong redheaded mare: he had me do the canter down the line and halt in the middle, then trot the second fence exercise (which I had already done a lot with her), and also had me canter a jump on a bending line, then after landing, put her into counterflexion on whatever lead she landed and do an immediate 15 meter canter circle. Very effective at encouraging her to rock back and listen after landing a jump!
Good luck!
Sounds like my guy the last two years and still is at odd moments when he’s less sure or himself or just being a big baby.
Do trot and canter poles. There are all sorts of designs out there, just google ground pole exercises for rhythm and balance. There are also various exercise configurations for low jumps and are fun to play around with. Keep the jumps low but I would add grid work as well which should help get him off his forehand. Mostly it’s a strength, balance, maturation issue, or at least was for my 7 coming 8 year old. Trotting fences has helped my guy tremendously as well.
I wouldn’t really fault a horse that lands in a pile when you’ve put them to a bad distance. That said, definitely work on strengthening the canter on the flat, tune up those downward transitions, and then gridwork. Doesn’t need to be big, in fact I would stick to small fences, basically cavaletti - and start with bounces and one strides, slowly working your way up to 3-5 in a row. I might also use the “wheel of death”, 4 low fences on a circle, to encourage a balanced landing. Or the one with a handful of fences set up in a zig zag on the centerline. Definitely DON’T overdo it with these exercises, though, or you may be asking for injuries! Start slow and quit early.
Horsie should be able to take care of himself even at a bad distance, because yeah, they are going to happen sometimes, but if you’re constantly chipping and taking flyers, maybe some practice for YOU is in order too. Set out a course of poles or cavaletti and work on your eye so you can put him to the best spot every time.
All good suggestions above. I would also recommend some hill work to develop strength. Work on down hill half halts, starting at walk and trot, asking the horse to fold his hind legs and carry himself down the hill. Use your upper body and core, as little hand as possible to help him balance. Progress to cantering down gentle hills; give a big half halt at the top, then move with him down the hill, he should learn to maintain balance and rhythm. If he speeds up like a train, do a downward transition.
I know you said non-jumping, but I think gymnastic lines are a GREAT way to address this. Basic ones–four poles to an X, one stride to a vertical, one stride to another vertical, two strides to an oxer type things. What you are looking for is not for him to allow YOU to rebalance him, but for self-carragie–to teach him to rebalance himself. Building the gymnastics and adding each additional fence in a progression will inspire him to not land in a heap because he sees what’s next. Like all gymnastic work you are there for support (mostly from your leg) not to manage the ride through, so stay out of his mouth and make him figure it out on his own. He may find this physically taxing and/or difficult, so start in small doses and work up to a full school.
You can set up the canter cavaletti going around a turn, like Dr. Doolittle suggested. Lunging a horse over them first, so that they are not dealing with your weight works well, too. I set them up like a fan, with the poles closer (about 4’ apart) toward the middle of the circle (the middle of the poles are set a 9’ apart) and much wider toward the corner. They should be able to trot closer to the inside and canter more to the middle and outside of the poles.
I am currently doing this with my downhill built OTTB. If she meets the cavaletti on the inside, she has learned to shorten her canter stride. She will lengthen her stride, if she meets them on the outside of the poles. She makes the choices.
I lunge her over a small square oxer, too. She learned how to “pat the ground” in front of it, instead of leaving from a ridiculously long distance. Now, all of this has translated to jumping with me on her back. 
I found landing ground poles to be invaluable in helping the horse learn to sit and balance his canter in the first stride after a fence. I set them a bit short 10-11’ depending on the approach. There was a time I didn’t jump at home without that landing pole. With limited poles for a line of two jumps I would put one before the first jump and one after the second.
For flat exercises to help him come to terms with the down transitions the 10-10-10 exercise from 101 Dressage Exercises might help. Basically it is canter 10 strides, walk 10 strides, canter 10 strides, trot 10 strides, repeat the CWCT pattern. I like to follow the 101 Dressage Exercises Needlepoint pattern while doing 10-10-10 so that I’m not just going large around the arena.
