Hi, my 4-month old Berner pup's left hind leg seems to be buckling at the joint. It buckles out (not forward or behind). He doesn't seem to notice it much, not in any pain, didn't injure it, still runs/plays. But it's very visible when he's walking slowly. My vet doesn't seem to be too concerned-said it could be just growing pains. Any ideas of what this could be? I've looked at dysplasia, luxating patella and the symptoms don't seem to all match up. Any ideas? Much appreciated!!