Imagine you're at home when out of nowhere a stranger enters, makes himself at home on your couch, and informs you that he will be living with you from now on. That would make you incredibly uncomfortable, protective of your home, and probably even scared.
Now you know how your cat might feel if you bring a new animal home. Of course this doesn't mean you should not get another pet - but there are things that you can do to help your cat cope with and feel more comfortable with your new pet.
Remember, when introducing a new pet into a household with a cat, you should always take things slowly. Don't just let the new animal roam the place freely, as this can make your cat feel threatened, which in turn can lead to a hostile reaction. Start slow and be patient. Try putting the two animals in the same room and watching them closely before attempting to release your new pet into your cat's territory.
It's a good idea to visit a veterinarian with the new animal before introducing him to your cat. You want to make sure that your new pet is healthy and will not be exposing your cat to anything that is possibly contagious.
Something you can do to help your cat deal with a new pet is to keep their items separate. Each pet should have its own water and food bowls, litter boxes (in the case of two cats), and anything else. It's also recommended that you give the two animals their own space in the house away from each other so that they can feel safe and secure in their own territory without feeling like their space is being invaded. Give your cat lots of love to make sure he knows that he is not being replaced and does not feel neglected.
You can also use a stress relief product like ComfortZone with Feliway to help your cat adjust to the new pet. ComfortZone works by releasing cat pheromones into the air, which make the cat feel secure and at home. ComfortZone can help reduce the cat's fear and stress, along with any associated negative behaviors. For a more in-depth explanation of why ComfortZone is such an effective way to reduce stress in cats, you can visit their "How it works" page.
Source: petplace.com