Hepper blog

Search our database of over 9,984 posts with up-to-date information from our experts and veterinarians.

Hepper is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no cost to you. Learn more.

How to Introduce Two Cats When One Is Aggressive (11 Vet-Approved Tips)

By Nicole Cosgrove · Reviewed & fact-checked by Dr. Paola CuevasVet Approved
Dr. Paola Cuevas
Reviewed & Fact-Checked byDr. Paola CuevasMVZ (Veterinarian)
Paola Cuevas is a veterinarian and animal behaviorist, with over 18 years of experience working with a variety of species. Her passion is animal welfare and focuses on the importance of preventive medicine. Paola has skills in the fields of nutrition, microscopy, clinical pathology, diagnostic imaging, and endoscopy as well as extensive experience in animal training through positive reinforcement. As our in-house veterinarian, Paola is very happy to share her knowledge and experience with our readers and hopes to be helpful with any issue presented by your non-human family members.View authorThe information is current and up-to-date in accordance with the latest veterinarian research. Read about our vets
Share
two cats fighting with one being aggressive to the other

Introducing new cats can be a challenge. It can be especially difficult if one cat has lived its entire life as the only cat in a household or if one cat has had very little socialization at a young age. In these cases, it is not unusual for that cat to show signs of aggression toward the other cat, and this can, at best, lead to the two cats not bonding and, at worst, fighting. There are steps you can take to help prevent or at least minimize the aggression, but it can take time and a lot of persistence and consistency to encourage a harmonious relationship between the two felines.

Whether you’re introducing cats for the first time, have cats that have never really gotten along, or are reintroducing a cat and there is aggression, try the following tips to help encourage a more peaceful environment.

The 11 Tips to Introduce Two Cats When One Is Aggressive

1. Don’t Let Them Resolve It Themselves

Some owners have the notion that letting aggressive cats get on with it and duke it out will resolve the situation. In truth, this is only likely to cause anxiety and make the situation worse. The non-aggressor will find the whole experience harrowing and difficult and will be much less likely to approach the aggressive cat in the future.

hugging-an-adorable-bright-orange-cat-stress
Image Credit: RJ22, Shutterstock

2. Get Them Neutered

Unneutered male cats are more likely to be aggressive than neutered males or females, and this is especially true if you have two or more in the same house. Cats are territorial, and even if the cats are littermates, they may look at the other cats as invaders of their rightful space or resources. There are other benefits to having male cats neutered, too. They are less likely to run away, and neutered cats are also less likely to get ill plus they have a longer life expectancy.


3. Give Them Space

Give each of the cats their own space away from the other. Ideally, the space should be in separate rooms. Allow them time to get used to their spot before introducing the cats and if things do get heated, you can remove each cat to their own area.

cat near door at home
Image Credit: Africa Studio, Shutterstock

4. Provide More Than Enough Resources

You should also look to provide additional areas for your cats to chill out. Make sure you have enough scratching posts and beds that they can have at least one each. You should also have one litter tray per cat, plus one extra, and you can add extra perches and other locations for your cats to go and cool down or get out of the way.


5. Ignore the Aggressor

If one cat is getting aggressive, it is very easy to make a fuss over that cat by providing them with attention in a bid to try and calm their behavior. However, your cat will feel like they are being praised for their aggressive actions, therefore encouraging them to be aggressive again in the future.

Abyssinian cat hisses
Image Credit: Slava Dumchev, Shutterstock

6. Reward Positive Behavior

Instead of fussing over your aggressive cat when they show aggressive tendencies, you should praise them, love them, and even reward them with a tasty treat when they calmly smell and groom the other cats. Initially, you should reward the cats whenever they do anything positive, and make sure you do it every time. Over time, you can reduce the frequency that you reward until, eventually, you only need to praise or reward them occasionally.


7. Try Calming Pheromones

Calming pheromones are natural and they can be used to calm any anxiety in cats. They are more effective on some cats than others, and if your cat is really riled up, then pheromones may not help clear the red mist. But they are worth a try and many owners have enjoyed success with these types of products. Make sure you choose the “multi-cat” kind because there are different products available in the market.

Feliway MultiCat 30 Day Starter Kit Calming Diffuser for Cats

8. Separate Them

If one of your cats is being aggressive, you need to separate them. Ideally, you shouldn’t get in the middle of the fight because cat claws can do some serious damage. Get their attention and then move the cats away and into their own separate areas to calm down.


9. Introduce Gradually

Never try rushing an introduction. Start by interchanging toys or blankets with the other cat’s smell and pairing the presentation with treats. After a while of doing this, the next step is having the cats separate, ideally with a barrier like a stair gate between them. Let them get used to the smell and the sight of one another. Once they can sit or go about their business separated by a barrier, you can try introducing them for a few minutes at a time.

If they remain calm, pair these introductions with positive experiences, such as play or even a treat. You should be very aware of their body language and prevent any interaction if they show precursors of aggression, such as hissing. Separate th

cat smelling toy in the living room
Image Credit: Magui RF, Shutterstock

10. Encourage Grooming

Some owners have had luck putting tuna oil on their cats. They are so busy licking a tiny bit of fish oil and grooming one another that they effectively forget to be aggressive. It does, however, leave your cat’s coat sticky and covered in tuna oil!


11. Change Their Experience and Perception

If you can change your cat’s experience in the presence of the other cat by encouraging play and using toys, food, or treats to your advantage, it could be enough to prevent aggressive behavior, and if you continue to do this when they meet, your cats may lose the urge to fight.

Final Thoughts

It can take some time to introduce cats that are aggressive to one another. You need to take it slowly and not force the situation to ensure that your feline friends have a gradual introduction and don’t get too anxious. Ensure they have their own spaces that they can retreat to, and try to pair each other’s presence with positive experiences and good outcomes as your primary technique. Besides this, pheromones or even a tiny bit of fish oil could be enough to help them bond.


Featured Image Credit: Photo object, Shutterstock

Get Hepper In Your Inbox

Pet care tips from our vets and experts, straight to your inbox.

List

Select all that apply.

You may opt-out at any time. View our Privacy Policy for more information.

Nicole Cosgrove
Authored by

Nicole Cosgrove

Join the conversation

Ask a question, share your story, or send private feedback.

Rate this post
Required to post. Only our editors see your rating.
Who should see this?

A human reviews every comment before it appears. Your email is never published.

Picked to go with this article

SiiPet LitterLens Litter Box Camera Review 2026: Our Vet’s Expert Opinion

SiiPet LitterLens Litter Box Camera Review 2026: Our Vet’s Expert Opinion

Have you ever wanted to be inside your cat’s litterbox? Well, no, neither have I. BUT, have you ever found yourself wondering whether or not your cat’s litterb…

Dr. Karyn Kanowski
By Dr. Karyn Kanowski ·
Litter-Robot 4 Review 2026: Style, Convenience & Our Final Verdict

Litter-Robot 4 Review 2026: Style, Convenience & Our Final Verdict

When it comes to automatic litter boxes, there is one brand that has always reigned king: Litter-Robot by Whisker. This quintessential auto-cleaning litter box…

Sara Seitz
By Sara Seitz ·
Sound Oasis Pet Sound Therapy System Review 2026: Soothing Anxious Pets One Step At A Time

Sound Oasis Pet Sound Therapy System Review 2026: Soothing Anxious Pets One Step At A Time

Pets come in all shapes, sizes, and personalities. Some exuding an air of confidence while others are slightly more nervous. If you happen to have an anxious p…

Lisa Lee
By Lisa Lee ·
20 Strange Cat Behaviors Explained (Vet-Reviewed)

20 Strange Cat Behaviors Explained (Vet-Reviewed)

If you’ve ever watched cat videos (and who hasn’t?), you’ll know that cats simply act in ways that are strange. Sometimes, these behaviors have obvious causes.…

Kristin Hitchcock
By Kristin Hitchcock ·

Keep reading

More stories you might like

7 Pet-Friendly Hotels in and Near Casper, WY (2026 Update)

Casper, Wyoming, is a great place to visit, with several attractions, including waterfalls, the Werner Wildlife Museum, and the Nicolaysen Art Museum. It’s als…

Brooke Billingsley
By Brooke Billingsley ·
7 Pet-Friendly Hotels in and Near Casper, WY (2026 Update)

9 Pet-Friendly Hotels in Kansas City, KS (2026 Update)

Sadly, there aren’t that many pet-friendly hotels in Kansas City, KS. In most cases, you will be able to find somewhere to stay, but you may only have a narrow…

Kristin Hitchcock
By Kristin Hitchcock ·
9 Pet-Friendly Hotels in Kansas City, KS (2026 Update)

10 Pet-Friendly Hotels in Pismo Beach, CA (2026 Guide)

Pismo Beach is roughly halfway between Los Angeles and San Francisco and is a relaxed beach town known for its beautiful ocean and mountain views. Beaches, hik…

Elizabeth Gray
By Elizabeth Gray ·
10 Pet-Friendly Hotels in Pismo Beach, CA (2026 Guide)

The Most Popular Cat Names That Start with N (Updated for 2026)

Before bringing home a new cat, you’ll have some important decisions to make. One of the first should be who will be your cat’s veterinarian, but before you es…

Elizabeth Gray
By Elizabeth Gray ·
The Most Popular Cat Names That Start with N (Updated for 2026)

Cat Vision vs Dog Vision: Who Has the Better Eyesight? (Vet-Reviewed)

Cats and dogs are known for their highly keen senses, such as smell and hearing, that are superior to those of humans. It would make sense that both of these a…

Sarah Psaradelis
By Sarah Psaradelis ·
Cat Vision vs Dog Vision: Who Has the Better Eyesight? (Vet-Reviewed)

Boxie® Cat Litter Review 2026: An Expert’s Guide

Even the fluffiest, best-cuddler-awarded kitten uses a litter box, which means he or she also has a human at home to tidy up after her. If this is you, and it’…

Shelby Loeppky
By Shelby Loeppky ·
Boxie® Cat Litter Review 2026: An Expert’s Guide

How To Get Cat Urine Smell & Stains Out of Clothes: 4 Simple Steps

A cat’s urine tends to be more concentrated than that of other pets. On top of that, when bacteria start to decompose the urea in the urine, it releases an ups…

Nicole Cosgrove
By Nicole Cosgrove ·
How To Get Cat Urine Smell & Stains Out of Clothes: 4 Simple Steps

How to Get Cat Urine Smells & Stains Out of a Couch: 6 Expert Tips

Cats are funny, gorgeous, elegant, fluffy goofballs that we just can’t enough of! They can go from being completely adorable and loveable one minute to annoyin…

Nicole Cosgrove
By Nicole Cosgrove ·
How to Get Cat Urine Smells & Stains Out of a Couch: 6 Expert Tips