Rear leg lameness can be caused by luxating patella. The knee cap or patella is not riding in the grove properly so it can pull to the side on knee flexion thus causing strain of the muscles in the leg and periodic lameness after exercise and bunny hopping. Your dog will also compensate by shifting his weight to the opposite side thus causing spinal subluxations as well as shoulder subluxations on the opposite side.
Animal Chiropractors are expert at evaluating this problem and helping your dog since they look at the whole dog and not just the knee.
Please call Dr Bruce at 781-337-1180 or email at indekchiropractic@gmail.com