Cats are very territorial and may highly resent other animals moving into their home. If you have dogs, birds or small animals, you will have to make special arrangements for them to coexist with your new pet.
If you have a dog, your new cat or kitten will probably be terrified by him especially if the cat has never lived in a home with dogs or has seen dogs before. Introduce him to the dog gradually. Let the dog sniff the cat under a door so that they become accustomed to each other's scent. After a day or two, place the cat in his carrier so that he can see and smell the dog from a safe place.
When you feel the time is right, bring your cat out and let the two animals meet. Do not leave them alone together until you are sure that there is not going to be a fight. Some dogs and cats learn to live together, while others have problems establishing territorial boundaries and prefer to live in separate areas of the house. You can best determine if your dog will accept a cat and if your new cat will like living with a dog.
If you have small animals, reptiles, birds, or fish, you might not want to introduce them to your cat. Because cats are natural hunters, they may see your guinea pig or bird as prey or toy.
The other pet may feel threatened and develop stress if he comes into contact with the cat. If you allow your cat access to the room in which you house other pets, make sure that the cages or tanks are secure and that the cat cannot get into them.