Ok, so here is what happened. I believe that my horse pulled his upper left shoulder muscle. He pulled up limping a couple weeks ago. You could tell he was limping but it wasn't sever. It is most noticeable at an extended trot when the left leg extends forward. He doesn't extend the left leg as far as his right leg. I examined his shoulder. There is no obvious swelling or heat. When I pull that leg forward to stretch it he pulls it away and acts sore and flinches in the shoulder area. There seems to be a muscle knot at the very top part o the shoulder almost near the whither area. I have been putting Absorbine ligament on his shoulder and it has gotten a little better. He is not limping anymore, but just acts sore and stiff in his shoulder. Any advice or treatment ideas? Has this ever happened to anyone?