Rats and Other Animals This is a really tricky subject. You REALLY need to know the personality of your other animals to know if any introductions to your rats would be a wise decision to make. Does your cat seem to have a strong hunters instinct? Then don't give him access to your rats. Research the breed of your dog. Is your dog a terrier? Almost all terriers were bred to hunt and kill small rodents. So that would not be a wise idea. Our dog is a sheltie, a herding dog. He is pretty accepting of other animals and at the worst, just tries to herd our rats around the room. "Now let me see here." "My, My, My... My work is never done." "I must keep those doggie eyes of yours clean. Now hold still." Ferrets are predatory animals and were domesticated to specifically hunt and kill small rodents, so never introduce ferrets to your rats. You should never introduce your rats to any of the smaller animal companions in your household. Rats are predatory animals and would most likely kill and eat an animal which is smaller then themselves, such as mice, hamsters, gerbils, birds, fish, etc... Animal companions which are larger than your rats, such as rabbits and guinea pigs, can sometimes get along with rats. We've heard of these introductions working out well for some people and very badly for others. We've unfortunately heard some real horror stories of introductions gone bad. Someone who was positive they had a lazy house cat, quickly discovered their rat hanging from their cat's mouth. Big dogs sometimes don't know their own strength. We know about a very friendly husky who loved their owners rat, but got so excited playing with it, that he almost bit the rat in half. Both rats died from their injuries. We've also heard horror stories with reversed effects. We know of a rat which killed their owners guinea pig. We've even heard one story where a families big male rat, quite swiftly, killed many of the newborn kittens that this families mother cat had recently birthed. The easiest and safest thing we recommend is to just keep all your other animals away from your rats. However, if you really want them to be together during play time, the best advice we can give, is to be very, very, very slow and cautious about introducing them. If any violence erupts, separate them immediately, and don't try it again. We spent weeks introducing our dog to our rats before we felt comfortable with it. For the longest time we just let them sniff each other's noses. Then we would let the rats out while Maxx was leashed in the corner of the room. We would hover right over him, looking for ANY signs of aggression or rough play. It was months before we trusted Maxx enough to let him loose with the rats, and we will NEVER leave Maxx unattended with our rats. As you should NEVER leave your rats unattended while loose with other animals present.