We took Tank and Orson out front. Orson to play and Tank to take his daily constitutional. I was thowing snowballs for Orson and Tank went out to do his thing then he started to walk all funny. He was lifting up a back leg so I thought maybe he got some ice in it. I rubbed it and when he put it back down all of a sudden he could not walk at all. Thankfully hubby was out there with me and I screamed at him to come over where I was. We carried him into the house. I don't know how I did it, I guess adrenalin goes into high gear - took me a while to quit breathing hard. Anyway, he was fine once he got into the house. It is single digits here and the only thing I can think of is that the metal plates in his back legs caused him to seize up. I am going to have to be very careful with him in this cold weather especially if hubby is traveling.....there is no way I could have got him in the house by myself. I would have been totally freaking out!