Oh...I know the answer to this one!
LP can be caused from either. If the vet does an x-ray, they can usually determine if it was from an injury because the ligaments that attach to the front of the knee cap will have visible tears in them. They are not present when it is genetic because that is the natural placement of the joint, rather than a forces displacement in the case of an injury. Ahh...that med school did pay off a little.
