We have a cat and a dog, a friend has offered us a puppy, would they have a good relation? Cats tend to ignore a new canine guest, but this doesn’t mean that the cat will right away accept the newcomer. Animals need time to get along well between them, and it is not necessary to push them, avoiding possible trouble. The same happens when a new dog comes along another already established. Feed them separately to avoid fights. Remember that the newcomer is invading the other dog’s territory; be sure of taking care of all the needs of the old dog, so he can feel that his dominant position is not threaten by the intruder.Hierarchy is important for dogs due to strong instinctive feelings coming from their ancestors (the wolf packs). When a puppy is the newcomer, fighting is less probable; a grown dog can threaten the hierarchy. The strict social structure within a wild dogs pack prevents serious conflicts, and this structure still remains among their domestic relatives. It should favor the established dog so there are less possibilities of fighting with the newcomer, but remember temperaments can change. It would be a great idea to leave them first on a neutral zone, out of the house, like a park for instance. Generally female dogs are less aggressive than males. To introduce a younger mate could cause a major disposition in the old dog, once they get use to playing with each other.