[sganow]

It sounds to me like it's probably luxating patella. Our little Maggie has grade 3 LP in both back legs. When I dry her off, those little knees pop like crazy. I have to be SO careful. She has only had one real flare-up where we had to take her to the vet for an injection and some pain and anti-inflamatory meds, and had to keep her rested so it would get better. She has been fine ever since. She is not in pain or anything, so the vet agreed that as long as it isn't bothering her or becoming a chronic problem for her, that we can just wait and watch her closely to see how she does. It it ever gets to being a real problem then we'll have to get surgery.

Your vet should be able to check for this very easily and tell you if that's what it is or not. If so, then the vet should be able to tell you what grade it is (grade 1 through 4, with 4 being the worst). I would have the pup checked and get advice from the vet. If not satisfied, there's nothing wrong with getting a 2nd opinion. In the meantime, I'd be careful with those back legs. Good luck!