I agree with everyone above about the Glocosamine Chondrotin supplements and limiting jumping as much as possible. When I found out Georgie had LP in both hind legs I cried and the vet assured there was alternatives to surgery. I did take him to get the right leg repaired as it was grade 4 (that was in 2008) and the left leg hasn't gotten any worse since then. We give him supplements and he is doing great!
My nieces Yorkie had it in both legs as well. He would switch off legs when he ran. He never whined and it didn't slow him down either.
I would ask the vet what grade LP it is but I am sure Louie will be fine