Anyone who has multiple cats can tell you that introducing a new cat into the mix can be difficult. Existing cats usually look at the newcomer with anything from disdain to hatred and will often respond by hissing, growling or even attacking. If cats have been domesticated for thousands of years, why do they still act this way?
If you have been reading this “Learn to Think Like A Cat” series, something that keeps coming up is a domesticated cat’s relationship to their wild ancestors and how many of those instincts remain. Of the various cat species, only lions live in social groups, with all others being solitary hunters that only come together to mate. A pet cat’s ancestors are similarly solitary and won’t normally live in groups. Despite thousands of years of selective breeding, many cats will continue to have this drive to be by themselves. In a cat’s mind, another cat is a potential competitor. The newcomer may compete for food, attention, toys, beds, or that perfect sunny spot on the floor. Because the wild cats viewed others in this light, pet cats will also. The home is their territory, and that new addition is invading their space.
Cats are also very much creatures of habit. Any change at all in their home or environment has the potential to cause them stress. We can see abnormal behaviors when a new couch is brought home or the carpet is changed. It’s even worse when the new thing is another living creature that can react back to them. A cat will react to something new either with fear or with aggression. In the former they will hiss, growl, and avoid the new situation. In the latter they will hiss, growl, and potentially attack. Both types of behavior can look similar even though they come from different behavioral sources.
The new cat is also undergoing changes, whether it’s a kitten or an adult. Even though they don’t see the new home as “their” territory yet, they do see plenty of new things. As I mentioned above, they may react to those changes with hissing and growling. They are doing it out of fear but an existing cat may see this behavior as a threat and respond accordingly. Again, it goes back to the idea that wild cats are solitary animals with a well-defined border to their territory.
Cats don’t “need” to have a companion and most are perfectly content to be alone. Their nature means that they don’t get lonely for another cat unless they have grown up with or otherwise become bonded with them. If you are thinking about adding a new cat to your home, do it because you want one, not because you think your cat needs one.
In a home, cats can learn to live with each other and even like each other. Introductions should be made gradually and be supervised until they become comfortable with the changes. Even so, it’s not uncommon to see occasional hissing. These are all normal behaviors where a cat is reacting on instinct.