We have had our dog since Saturday and J has been in seventh heaven since then. She is the perfect make and model for him (a border terrier), being small so that he can hold her lead without pulling him and good-natured and easy-going (and calm!) so that she is not fazed by his boisterousness. He is so sweet and tender with her, genuinely solicitous and concerned for her welfare, that I think it is surely a good thing for children to have a pet like this. He says several times a day "I love you and I love Pup and you love me and Pup and Pup loves me and you" that it seems to be re-configuring his sense of family... And she herself (named Pup, apparently because that is the only name she would answer to as a puppy) is really very sweet... I am no great dog-lover but I really could be convinced.