Hi Dorothy, My Daisy has a luxated patella and she's had it since she was about one year old(she's 5 now). My vet doesn't recommend surgery for her right now but it could happen eventually. She gets around great with it but I do have to help her get on top of the sofa/chair/bed sometimes. I have foot stools and steps all over the house for her. Me and my vet don't think she's having alot of pain so she is ok for the time being. I understand that this condition is fairly common in Chihuahuas. One of my son's Aussie's has a luxated patella also and his vet has trained him on putting the knee back in place. He gets around great also and is like a rocket dog most of the time. I wish your son best of luck with his little Miura. I'll pray for a quick recovery for her.