Three-legged Dog

Arthur's been doing this thing lately where he tucks his left front leg completely under his body. He used to just tuck the paw, but now it's the whole leg. There's nothing wrong, apparently, he's just sensitive about that side. If there were something wrong, he could get one of those doggie wheelchair contraptions, except, how does it work if it's a defective front leg and not a rear one? Hmm.