I agree Judith, I don't think chipping or tattooing would help if a dog was stolen, only if lost and someone is actively trying to find the owner. It's a horrible thought. I saw a programme on stolen/lost dogs once and it was quite distressing seeing the poor owners some who never gave up looking even years after. I don't leave Maggie in the car but that's mostly because she hates being left, but if I did I would definitely lock it. Maggie has a Barjo dog cage which if bolted would be hard to open, but I would never feel comfortable doing that because in an emergency situation you may need to get them out in a hurry. I have heard of people steeling cars not necessarily aware of dogs being inside so it would probably be better to lock the car and even then not out of site for long.