I have a 1.5 year old Boston Terrier with Patellar Luxation. This has been diagnosed, but I have not been given an official stage. Based on the descriptions I have read I would say she is a stage 2. I feel her knee pop sometimes, and I see her holding it up on occasion but I have never heard her cry. It really doesn't seem to bother her. At this stage should we get the surgery to prevent the problem from getting worse, or wait until it is worse and surgery is absolutely needed?