My 1-year-old Chihuahua, Denise, was recently diagnosed with patellar luxation. The vet said she has medial luxation. I know it is hereditary an and neither of her parents were health tested! The breeder never told me she had patellar luxation. I was told that her hind leg carriage was abnormal, but that she would grow out of it with age. When she was a puppy I noticed that she had an abnormal gait. The vet said her luxation is a grade 1. I've noticed that she can't extend her back legs fully.