We have a quite dominant 2 year old female who was introduced very suddenly to a very shy 6 month old female due to the little one being suddenly made homeless. It was awful for several months but they now (1 year on) tolerate each other. Whether they will ever be friends I don't know but as the little one has grown their relationship has changed and I am really not sure which is the most dominant. If Caspar is easy going and gets on well with your dog I would imagine that he would be fine with a kitten. How do you think the dog will be? We thought that our dog would be very tolerant but he was the worst of all, mainly due to curiosity rather than malice but its hard to tell a small kitten that the dog is just curious.