Backstory. 3 year old (will be four in July) Shire gelding. He has been slow in development, right now he is back to weedy looking: narrow chest, butt high. He is definitely on the post legged side, as was his dam. He is broke to lead, broke to some ground driving. He Was going to go out to get trained and hitched. However, I’ve seen twice in the last month his left hind ‘catch’ in the classic locked (upward fixation of the patella). Both times he resolved it very quickly, so I suspect it has happened many more times. He is currently definitely showing the classic little hitch in that stifle as he first steps off, especially turning to that side. In hindsight, this is probably the basis for some out of character explosions when asked to pick up that left hind or the left front. He has also often been a klutz. I was attributing that to being a young gawky horse, now I wonder.
So. The good news is all of the ground exercises I’ve been looking up seem like they can be geared towards advancing his brain at the same time as strengthening his stifles. The bad news, he isn’t going out for training at the moment since tie stalls, limited turnout, and all aren’t a great idea.
My questions: what can I proactively do: nutrition, favorite ground exercises, other bright ideas? He isn’t going to grow out of this, I suspect based on his dam’s conformation. So how would you strengthen a post legged draft for the best outcome? His planned job is not high speed, but it is stress on the flexor tendons: weight pulling (logging).
Another odd note…I have never, ever seen a horse who prefers to lie down to sleep as much as this guy…
I should add: vet feels like going the strengthening through exercise route is definitely the first and preferable route.
Horse in question (Sunny) on his third birthday. He is butt high here, but you can see that hind end conformation
The butt high stages, which does straighten the whole hind end, is definitely at least one cause right now. You can’t tell his final hind end conformation from this butt-high stage.
Work him. Ground drive, pony him if that’s an option, work over raise poles, all the things that strengthen the quadriceps which are largely responsible for the release of the ligament from the hook
MOST of the time, maturity and fitness resolves this.
Your vet is right. A rising 3yo, in a butt-high stage, who is only catching, needs work first, and this might mean a couple of years of a solid strength foundation, and maturity
Also, make sure his hind feet are trimmed very regularly, so his toes don’t get overly long, which just exacerbates this issue.
Don’t you drive? Or am I mixing things up? Walking all over hill and dale is a fab fitness builder. Hitch this guy up and walk him all over. Or if he’s not broke to drive just yet, tie him beside or behind and have him walk with you when you drive your others. Or pony him, if you’re riding. Or (maybe last choice, given his long legs 
) hand walk him.
If you’ve got a big eurosizer anywhere nearby, that’s also an option, but boring.
Just get him moving, though. Even setting up his field differently might help. Do you have a field with a slope? Set up feed at one end and water at the other.
Half an hour walking up and down hills every day will make a big difference pretty quick!
Backing up slight inclines in hand can be a great thing for this sort of horse. He needs to be handy and responsive backing up in hand on the flat, so that you can control him/manipulate him into straightness and doing the work should he just ‘shove’ himself backwards with his fores or get crooked.
Standing beside his hips and just gently tugging laterally on his tail to make that stifle ‘react’ and steady himself is a good isometric. don’t yank, just gentle tugs to require that stifle to engage.
Abequinetherapy on Instagram has some other good tips, and you get the visual to go along with it.
JB won’t agree 
but I like a squared hind toe on an otherwise normally trimmed foot to ease breakover. Slight a couple extra swipes, nothing bananas.
LOL Nope, I don’t aggree with a squared hind toe, because the hind foot needs to break over in all directions. I’m all for beveling additional breakover in, but do it from toe quarter to toe quarter in the same arc the foot is naturally shaped in.
A straight line across the front means it’s harder to break over in the lateral directions, however minimally, and that creates extra stresses on the foot upwards.
If there’s enough toe to square off, there’s enough to take the corners off too and accomplish the same thing in a more functionally correct way 
If you like podcasts than you might like this one from Dr. Lacher at Springhill Equine.
She talks about sticky stifles, stifle injuries, and diagnosing and treating. If I remember correctly (I listened to this quite awhile ago) the suggestion was mostly about strengthening the quadriceps. Poles, backing up an incline, balance pads.
Thanks for the replies. I’m glad to know I am on something of the right track. Feet are being addressed, I finally have a farrier again, and he is back on a 6 to 7 week cycle since the end of December (having gone from July to December with either no farrier or one that turned out to be really bad)
@Simkie yes, I drive. Sunny (the horse in question) is not yet broke to drive. And all involved feel that until that stifle is strengthened his serious training should wait. I’m not in a hurry with him. You are right on the pasture, he usually has a slope that he moves up and down. For the last two months however in a vain attempt to preserve the grass, he has been in a flat ‘small’ field of just shy of an acre during the day and in the quarter acre dry lot at night. Clearly more exercise is better.
It seems that all of the exercises will also in the long run help with his training. And my fitness…I see much walking in my future too! 
It will have to be in hand work at least for a little bit.
My understanding is that lunging, circles, and deep ground are all things to avoid? I wouldn’t mind that, I hate lunging. And the few times I have lunged Sunny he wasn’t all that joyous about it either. Is there anything else to avoid? What about turns on the haunches/shoulders? He really needs to learn to do those for driving.
@GoodTimes I will check the podcast!
A solid foundation of training doesn’t require discipline-specific work, so everything you do that’s appropriate for his young age, and his growth phase at any given time, will automatically serve his stifle issue, as well as lead to a more foundationally-fit horse when it comes to more “serious” work
Walking is HIGHLY underrated by many as a foundation of fitness. A strong marching walk does so much good for the entire body.
Correct, circles and stifle issue don’t go together. Carefully condition work on softer footing can be very useful for sticky/catching/locking stifles since they require more leg muscles for the work. I’d limit it to walking though, and it doesn’t take but a few minutes a couple times a week, in addition to the regular footing work, to make big gains.
Since TOH should start from a walking action, and if you keep the movement simple (ie just a couple steps over at a time) then that’s all you need right now for him to learn the basic movement of what you’re asking. Once he’s stronger, you can work towards less forward and more over. TOF can also be done but IMHO I would put a good month of more focused fitness on him. You can always, always still teach him to step forward and over when asked as just part of basic ground skills, and when the time comes to do more correct TOF, he’ll have that already downpat
I needed to come back and clarify this.
I mean I disagree for things like the OP.
A squared toe, anywhere along the breakover semi-circle, on either hind or front feet, has its place if you need to direct a purposeful breakover to help managed a conformation issue or an injury. That’s very different, and requires a farrier/trimmer to carefully watch how the body has created its own breakover wear point, and whether that’s appropriate for what you’re trying to correct or at least not make worse.
I don’t agree with a squared toe for this type of issue.
In my opinion and experience, a KISS approach is the answer. Get him out walking, however you can. Handwalk, let him follow as you work other horses at the walk, set up his field for more walking (if you can!) If he’s agreeable, even leading him from a gator or something will work. It doesn’t need to take up a ton of time, maybe start with 10 min/day and add 5 min a week. Sure, do whatever training stuff he needs to learn, but it’s forward march walking, preferably up and down gentle hills, that’s key.
It’s fab for young ones, cause it’s just walking, ho hum, not a hard question, but you can show them so much and it’s such a nice intro to a “work” routine.
Have fun! 
