Pam, re: "The only thing these people have in common is that they have dogs at home. This is sort of strange, too, because Trevor used to live with 2 dogs and got along quite well with them."

just a comment - that isn't strange at all really, because the dogs Trevor smells on those people are not the dogs he lived with. Generally if a cat comes home from the vet after surgery it's companion cats will growl or hiss at it as though it's a stranger because it brings different smells home with it - they don't even care that it is the same animal!!!