As long as I've had my horse, he has had some fluid along the lateral or common extensor tendon sheath. When we had a pre purchase exam done, we had xrays and ultrasounds down and there was no damage to the joint or tendon...just fluid. He has always been sound, no pain/heat on palpation, and he flexes perfectly. I've had him for two years and the fluid has never changed...always looks the same. Today I went out and it's completely gone....looks almost exactly like the other leg. No heat/pain still. Completely sound. Jumped him around and the fluid has not returned. Has anyone ever seen this happen? I'm sort of worried because it has always been the same and now it has just seemingly disappeared..