Introducing a new kitten to the home can start out as one of the sweetest experiences of pet parenthood — and then the hissing begins. Once cats start to get territorial, it can be a very frustrating experience for pet parents. 

When will my cat stop hissing at this new kitten? 

‌It’s a common experience, but not an unsolvable one. The solution starts with an understanding of why the territorial behavior begins in the first place.

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Territorial Cat Behavior: Explaining Sibling Rivalry

As much as it doesn’t seem that way, established cats don’t hiss at new kittens just to be mean. There are multiple instinctual and social processes going on in the background. 

Cats Are Naturally Solitary

Wild and feral cats don’t “buddy up.” They hunt and prowl alone, so it’s understandable that established cats aren’t thrilled when a new cat arrives. They see the kitten not as a potential new friend or “little sibling,” but as competition.

Cats Are Territorial

An established cat feels like they’ve already done the work of staking out the home as their space. When another cat shows up, the first cat feels like they have to re-establish dominance. 

Cats Don't Like Change

Cats are creatures of habit. When a new cat enters the mix, the established cat goes on high alert. 

‌ Many change-averse cats may shift from anxiety to aggression faster, especially if they’re also less sociable. Cats who have had bad experiences with fellow cats early in life, and cats who have always been the only pet in the home, may have a harder time accepting new additions.

It's harder, but not impossible. It just means a little bit of extra work and caution on the part of the pet parent.

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Can't We All Just Get Along? 

No one can force cats to get along. but pet parents can structure the cats’ early interactions so older cats can work through uncertainties at their own speeds.

Keep Them Separate

On the kitten’s first day home, set things up so the cats can hear and smell  — but not see or touch — each other. This means separate food, water, litter boxes, beds, and so on.

Think of it as the cats having their own apartments. The older cat might still hiss, but they won’t be able to do any damage.

Introduce Them Gradually

If the hissing has stopped after a few days, have the cats switch “apartments.” Move the kitten care supplies to the kitten’s new room, but keep some of each cat’s bedding in place. This lets the older cat get up close and personal with the new kitten’s smell.

Give it about a week and see if the hissing dies down. If so, they can start to watch each other through a barrier. Screen doors and baby gates both work well. ‌

If after a few days there’s still no hissing, they can spend some supervised time together.

Cat Anxiety Medications

Like people, cats get aggressive when they’re nervous. If it’s been weeks and the older cat still hisses at the door of the kitten’s space, don’t be afraid to try some cat calming products. Pheromone sprays, diffusers, and anti-anxiety chews can all work wonders, and sometimes patience is going to be the best medicine.

‌Adding a new kitten into the home can be stressful. For access to on-demand support, and 24/7 Live Vet Chat with licensed veterinarians and behaviorists join Fuzzy today.

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