Sue, I read your post and I have a simalar problem. I have a lab that is 3 years old. Last October, after a day with the boys hunting pheasants our dog developed a limp in her left rear leg. She has been limping ever since. I took her to the vet and they x-rayed the hip and knee and found nothing wrong. There was some evidence that she may have had a pulled ligament. The vet said to keep her of the leg for one month. Well that was imposible, but we did get her from playing and did not take her to the farm. That did not help, her leg just began to lose the muscle. She runs and playes just fine, but when she slows down she begins to limp. If anyone out there has any suggestions please respond. Thanks Julie