My son let my dog off his cable wednesday and we searched evertwhere for him, friday morning he came back. He didn't come back with his collar or cable. Im Afraid he may have gotten tangled on a tree or something and stuck for a day and a half. It has been terribly cold outside at nights20's. Anyway he came in at 7am and was fine. He started eating and drinking immediately,had a normal bowel movement, went outside and peed. At 9pm noticed he was limping on one leg. It is now midnight and he won't come to me. We stood him up and he is acting like both legs hurt him. How can he be fine all day and all of a sudden be immobile? Could this be arthritis acting up after being in the cold or from struggling to get off the tree and it took a while for pain to kick in? What could this be? He is 2 to 3 years old pitbull.