I observed Red moving at liberty yesterday. When he left the gate after his morning medicine, he trotted away down the big hill doing his very big trot and then switched to canter - right lead, which puts more stress on the left hind. But he switched leads after only a few strides, and didn't canter far before he came back to walk. Although there was no obvious lameness, it looked to me like he was protecting his left hind. So last night, I did the "feel all over" on the left hind just to see if there were any sensitive areas. No sensitivity in the lower leg, and no sensitivity in the hock area at all. The small cut where he was kicked is healing, and there is a small amount of residual swelling above that, but there's no sensitivity anywhere, including at the top of the splint bone (which our regular vet thinks is the problem - her digital x-rays indicated that he might have a hairline fracture), which is a good four inches below where he got kicked. I kept moving up the leg. When I touched the area of his inside thigh behind the stifle joint, his ears went back, his head came up and he signaled that he was thinking about kicking me since it really hurt - and he's a horse who doesn't usually mind having his body handled. I suspect his residual lameness is due to his entire leg having been torqued - which could explain the sesamoid issue, the splint bone and the soreness inside the stifle joint - it may be that his hip and back are also not right. I actually suspect that while the hock may have something to do with it, the kick he received didn't cause all of these issues.
I wrote this this morning, before our vet/chiropractor came - a different person from our regular vet, and one who tends to focus on the whole horse, including metabolic issues. Now here's what she found and had to say . . .
There is some residual swelling at the hock - our vet/chiro said this could be because the kick irritated the tendon sheath of the tendon that passes over the hock joint at this point - she recommened we use Sore No More on it. This may not be the main cause of his lameness, although it could contribute to it. We lunged him briefly before she started to work on him - he was hardly showing any problems at all at the walk - just the slightest shortening of stride in the left hind. At the trot, he was at most one-half out of 5 lame to the left and about a 1 out of 5 to the right - this was much improved from the last time I lunged him about a week ago. He is still twisting the left hind slightly after it lands, and again, he wasn't bringing his left hind quite as far forward as the right hind - that's why the problem looks worse when he's tracking right as it amplifies the difference between right hind and left hind. The problem with the left hind isn't on the weight-bearing phase as the leg passes under the body - he's fine for that - it's as the left hind swings forward - its motion is slightly restricted and his stride length with the left hind is slightly shorter. She said, based on that, that he didn't much look like a horse with a fracture, although she could be wrong.
He did have some things that were tight and sore in his mid-back - not a usual area of problems for him. This could explain his fidgeting during saddling, and in fact, when I saddled him today he just stood there as he usually does. But he did have some other major things going on in his hind end - cramps and muscle soreness in particular places on the left side, likely from the almost fall and catching himself at the canter. Here are some drawings from a book that is a huge help to me - it's called Beating Muscle Injuries for Horses, by Jack Meagher - seeing this will help explain what Red has had going on.
This is the biceps femoris muscle - a problem with it will result in scuffing the hind leg and shortening of forward movement.
This is what is called the "belly" of the biceps femoris - problems with it will cause the same effects.
This is the semitendinosus - problems with it will result in shortening of forward movement and discomfort straightening the stifle:
And here is the semimembranosus - problems with it will result in shortening of forward movement, discomfort straightening the stifle, resistance to lateral movement and tracking inward during forward movement - this last one is something Red tends to do anyway and this has been exaggerated by his problem and is the cause of the twisting of the left hind foot that we observed. A hamstring pull or pull to the inner thigh (that's the exact area he showed sensitivity to touch in last night) can cause injury to this muscle.
She worked on these muscles for a while, and got a lot of licking and chewing and at least one very big yawn from Red - she said the yawn was the big release. She showed me how to do massage on these muscles - the book (which she had recommended to me) also has good instructions.
When we turned him out, he trotted off doing his big trot without a sign of a problem, and then cantered off on the right lead - without switching this time. She says that, if turnout and light riding (at walk for now) don't make things worse, that they are advisable. Many horses who are put on stall rest (sometimes this is certainly justified) never recover full function because the fascia at the site of injury become locked in place and don't move properly past one another ever again - in fact predisposing the horse to further injury. So movement is good, if the horse can tolerate it and the injury isn't made worse.
So Red and I will be doing our ridden work at the walk - we did it today and he was moving better and very happy to work. So it was the hock - the aggravated tendon sheath - but it also wasn't - the muscular issues in the hind end were also causing serious issues. Sometimes things aren't entirely what they seem . . .