Two nights ago I got to the barn with a lame horse. Fairly sure he slipped on ice in the pasture... :-(
Offside hind. Felt his leg from the hip to the hoof. No swelling. a very small, barely there spot of heat in his hock. He was fully weight bearing (in fact, stood with his opposite leg cocked part of the time I was grooming him(, let me poke and prod away, and put his leg through a full range of motion without resistance. But moving, he doesn't want to bend hock or fetlock- he moves the leg entirely in the hip.
Called vet, described it, he didn't think it needed an emergency call, try bute and stall rest and call back if it doesn't improve.
Buted, and he was a *little* bit better. My farrier (his previous owner/trainer) was out last night (does a lot of soundness work) and had a look at him. Palpated the heck out of his hind end and all he turned up was a teensy bit of tenderness in his hock and his fetlock. He didn't think the vet is necessary and I should just bute and rest him a few days and hand walk for exercise.... But... today he's not really any better at all... Heat in his hock is gone.... but I'm thinking with his tendency to be just a *little* bit on his toe behind, I might be dealing with a stifle issue and the lack of motion in his hock and fetlock is just coming down from up above.
I'm sorry to hear about your pony...Now, without actually seeing your horses way of going, i can be of no help to pinpoint exact location. But, IME, a regimen of bute and rest works wonders...but if you have an abundance of money, have the vet out for xrays and possible U/S...Regardless of what it is, its still going to require the two treatments above...soft tissue injuries can take months to heal. Good luck!
OK. Grabbed a short video of my guy out in the arena. Still no heat, no swelling, lets me move it through a full range, flex the hock and fetlock, he will stand with his opposite leg cocked with full weight on the stiff leg. But he moves like this. Vet says to keep resting, bute and hand walking, he's due to be out wednesday and will have a look then.