Red and I had our vet visit today. I really, really like my vet - she's extremely smart and knowledgeable, and a real pro about lots of things, but especially about lameness of any sort. She's good with the horses, and always takes her time - even if her schedule is running hours late. She also is good about explaining things to the human connections of the horses. She also knows my horses well as individuals and remembers how they move and any oddities about their bodies.
She watched Red on the lunge, looked carefully at his leg, asked me questions, and did a careful palpation (done the correct way, with the leg held up) of all the structures, including the ligaments and tendons. The swelling was down quite a bit from last week, but still visible. Red was very close to completely sound on the lunge, slightly less so when the left hind was on the outside, but still more than 95% good. Slightly less push with the left hind, but very subtle.
She said all the important structures - the suspensory ligament and the flexor tendons - felt fine - no swelling or tenderness. She said it was highly likely, due to the location next to the tendons and in an area where he has scar tissue under the skin from his splint bone surgery, that an adhesion - scar tissue from the surgery - had been attached to the tendon sheath and had moved (when he almost fell with me or from running around in the pasture), causing a small tear in the tendon sheath. This leaked synovial fluid, forming the swelling and causing minor lameness at the time. The fact that the swelling has gone down a lot and there is no heat or tenderness likely means the small tear in the tendon sheath was so small that it has already closed back up again.
After discussion, we decided not to ultrasound at this time, since she didn't think the structure of the ligament or tendons was affected, and ultrasound does a poor job visualizing adhesions. She also thought the 5% unsoundness was likely in large part to his hind end arthritic joint issues and him being out of work.
So we're cleared to start back to under saddle work! Very exciting! Obviously, if he doesn't work out of his stiffness, or he gets less sound or the leg starts to look worse, we'll rethink, but her opinion is that he'll be just fine. I let him go into the pasture and he trotted and then cantered off, as happy as can be.
(A note about tendon sheathes. Normally, an injury to a tendon sheath is a very serious matter. But most injuries to tendon sheathes are wounds - lacerations or punctures. These injuries present serious risks of infection, and often the structure of the tendon is damaged as well. Red's injury isn't of this type - it's wholly inside his leg with no exposure to the outside.)
So, this afternoon, we went back to work with a 15-minute walk ride - he was as good as gold, despite having been out of work for almost three weeks. It was great to be riding with him again!