When I went to pain therapy they would put my arms in icy water for 10 minutes then as hot as I could handle for the same. It makes the blood flood the muscles and tendons and yes it hurts. I took it pretty well.
I have a pit/boxer mix who scratches herself constantly in warm weather, mostly on our rugs, and will sometimes get tenderfooted as well. But there are times she gets excited and runs smack into a wall…no reaction.