I'm not into dogs but I understand how hurt to see the people who lose their dog and it not easy to let go. I would comfort them and I can suggest them to use guided imagery to help them to relived the emotion. It will helped them to picture the image of memory they has with their dog. I can suggest them to use collage and put some good pictures of their dog with them because the client can look at it and it will make them happy and have a good time by looking at it.