We have 4 OSB approx 18 weeks old. On Friday one of them has gone lame on her back right leg, she won't put any weight on it. I have had a close look, felt the leg etc but nothing obvious. She stays in the arc most of the time but does come out for feed/water and all else so no loss of appetite. I am calling the vet tomorrow but if anyone has any suggestions on what it might be that would be great, I am thinking muscle strain maybe. The pigs are in a large area that (at the moment) is not too muddy.