Image of cats fighting. Text is name of post: What to Do When Companion Cats Get Into a Sudden Fight

What to Do After a Sudden Cat Fight

So, you’ve just witnessed a cat fight.

Your cats have always gotten along…

Maybe they were even best friends?

They’ve never had a fight in the many years they’ve been living together. In the very least, they’ve always tolerated one another…

And then one day… Bam!

You hear those unmistakable, bloodcurdling kitty screams, and find your cats tangled up together, one rabbit kicking the other. Then one takes off running, once it finally makes it out of the other’s sharp-clawed grasp.

This is a scenario many cat parents have had the displeasure of witnessing. And it can be a very upsetting one, that leaves both you and your cats shaken to the core.

When a sudden cat fight breaks out between two cats that have lived together in harmony, they need to be separated immediately.

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What Causes Cats to Fight Suddenly?

Image of a cat fight on the floor

It can be really scary when your cats who have gotten along for years all of a sudden get into a fight. Usually this comes in the form of one cat attacking the other.

When one cat attacks a companion cat out of the blue, this is typically redirected aggression.

This is not to be confused with cats that have a history of consistent aggressive behavior. I will be covering that situation in detail in another article, which I will link here.

Redirected aggression happens when a cat is stimulated by something that causes their anxiety level to spike. Most of the time, this is caused by another cat that is outside. It can also be caused by a smell, a noise, a different animal, etc.

The cat becomes agitated, and feels unsafe. When this happens, since they are unable to directly confront the cause of their anxiety, they will redirect the resulting aggression toward the cat, dog, or human right by them.

If their long-time kitty friend is sitting nearby, they are going to be the reluctant recipient of this redirected aggression.

Why Should Cats be Separated Immediately After A Cat Fight?

If cats are separated immediately after a fight, they will usually cool off relatively quickly. This makes it much quicker and easier for their relationship to go back to normal.


When the cats are not separated, the aggression can continue, and this will change the entire dynamic of their relationship. If this is the case with your cats, I suggest separating them right away. In this instance, a complete reintroduction is necessary.

Tips for Separating Cats:

  • Never try to physically get in the middle of a cat fight, the aggression will more than likely be redirected toward you.
  • Do not start yelling, your erratic energy will just fuel the situation.
  • Sometimes, making a loud, abrupt noise will startle the cats, and cause them to disengage. (Bang pots together, drop something loud on the floor, snap a belt, etc.)
  • You can try using a couch cushion, or something similar to put in between them.
  • This is one of the only instances that I believe using a spray bottle, or squirt gun is acceptable, even encouraged.
  • Once broken up, wrap the aggressive cat in a towel/blanket (if you don’t know which is which, take your best guess. Which one is running away, trying to hide, and hissing? That one is likely the victim of the attack.)
  • Quickly put the aggressive cat into a darkened room to calm down.
  • Leave the room, and be patient.
  • Minimize stimulation (this means no playing, petting, scolding, etc.)
  • Leave the cat alone while he/she calms down

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Check for Injuries

*Warning* Graphic image of open wound below may bother sensitive individuals.

It is very important that you check for injuries, lacerations and tenderness after a fight. If you’re concerned that severe physical damage has been inflicted, take your cat to the vet. It’s better to be safe than sorry, and ensure that infection does not occur, and/or bones do not heal improperly.


An extremely common infection that occurs as a result of a cat fight is an abscess.

The attacking cat’s nail or tooth punctures the victim cat’s skin. Teeth and nails are covered in bacteria. Some of this bacteria is transferred to the wound. Since it is just a puncture it heals over quickly, but the bacteria sits in there festering and proliferating.

Pus from the infection builds up, and eventually causes the skin to burst.

This is very painful for the cat, and can be very scary for an unsuspecting guardian!

I speak from experience here. My cat Ellie was an abandoned stray, and had been dumped in an area with a huge cat colony. When I brought her home, she had two abscesses on her hindquarters.

She developed another abscess about a year ago, when she was accidentally let out by my roommate’s 4 year old. There was a neighbor cat outside, and Ellie ran up the huge oak tree in our backyard. Unfortunately, she wasn’t quick enough, and I helplessly watched as the neighbor cat bit her hindquarters.

A few days later, it burst, and left a bloody scene that looked like someone had been murdered.

Photos of my cat's abscess to show what an abscess looks like
Ellie’s abscess after it burst, and then when it was cleaned up. I know it’s gross, but it’s important to be aware!

Checking for tenderness is key in this situation. Abscesses typically develop on the hindquarters of a cat that is trying to escape, and on the face of a cat that is fighting.

Catching it before it bursts is ideal. You can then take them to the vet, and they will usually prescribe antibiotics, and decide on the best course of action.

When I first brought Ellie home with two abscesses, I was actually able to heal both abscesses naturally without going to the vet. But this took time and consistency.

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Related Articles:

Do Cats Need to Be Reintroduced After They Have Fought, or Can You Just Put Them Back Together?

The answer to this question depends on the circumstance.

You should always wait until the aggressive cat has calmed down completely. Check for any of these symptoms when determining whether or not the cat is still agitated:

  • Dilated eyes
  • Flattened ears
  • Swishing or erratic tail
  • Tail pointed downward, or between legs
  • Tail puffed up/bristled
  • Breathing heavily or erratically
  • Skin twitching
  • Pacing/restlessness
  • Growling
  • Hissing
  • Excessive grooming

If the attack was very mild, and both cats seem to have calmed down completely, you can test the waters. Take something that smells like the victim cat to the aggressor.

If you’re not sure which cat was the aggressor, take the scent-soaked fabric/toy/something similar to the cat that recovered the quickest.

Then switch it up, and have the victim cat smell the scent of the aggressor.

If there are any adverse reactions, such as hissing or growling, I would strongly recommend doing a full reintroduction.

If the reactions are neutral, you can see how the sight of each other causes them to react. They may act normal, and if that’s the case, it may be alright to put them back together.

If they react negatively to the sight of each other a reintroduction is the best option.

Even if everything seems fine, I still recommend using positive association by starting with feeding times and/or playing together.

How Long Should You Wait Before Reintroduction?

Deciding when to reintroduce after a cat fight involves observation and some kitty sleuthing. Time, in this situation, is a delicate balance.

On the one hand, waiting a long time leaves them to sit with a negative association regarding the cat that was once their friend. On the other hand, pushing them together immediately is not going to give them time to relax and cool off. This could quickly lead to another fight.

The severity of the fight, and the state of the cats post-fight is going to dictate the length and stringency of the reintroduction process.

If the fight was minor, and the cats calm down quickly, the reintroduction may go very smoothly, and quickly.

If the fight was particularly brutal, and one or more of the cats is displaying severe hostility or fear, you are better off leaving them separated for a greater length of time. Let them cool off, and don’t begin the reintroduction process if one, or both, are obviously still agitated.

Use your own discretion when deciding the length of time they should spend apart.

How to Reintroduce Cats

Cats looking at each other. Portrays reintroduction process for cats

Treat the cats like they have never met before. To prepare for reintroduction, make sure you are doing these two things:

  • Feeding both cats on a schedule (no free-feeding at all!)
  • Establish a room in the house that is going to be the “sanctuary room”

*The sanctuary room is a safe room with lots of cat items that they can rub their scent all over. (Blankets/towels for them, cat beds, cat furniture, scratchers, toys, etc.) Cats associate their own scent with a sense of ownership and safety in the territory. This room should NOT be a laundry room, or bathroom. The best option would be a spare bedroom.

Here are the basic steps for reintroducing cats after they have gotten into a fight:

  1. Keep cats completely separate, with no eye contact
  2. Wait until they have calmed down (I recommend at least a day)
  3. Begin feeding on opposite sides of the door at all mealtimes (keep door closed, still no physical or or visual contact yet)
  4. Observe for their reactions
  5. Move them closer to the door at the pace they permit
  6. Once eating closely on opposite sides of the door (without hissing, growling, etc.) install a screen door or put up a tall baby gate (such as this one)
  7. Feed on the either side of the baby gate/ screen door. If using a baby gate, cover it with some sort of cloth.
  8. Start farther back again, not right on top of each other. Establish their comfort line, and challenge them to step a paw over each time.
  9. Begin lifting up the cloth slightly, and observe their reactions. If they are comfortable, get rid of the cloth.
  10. Get them eating closely on either side of the gate/door calmly, while completely visible to one another.
  11. Take the gate away for feeding time
  12. Spend time with the cats out together, but always provide a positive activity, whether it be playtime, cuddles, clicker training, or food.
  13. Once the cats show no signs of aggression toward one another, they can be together on a regular basis.

The most important thing here, is to establish positive association, only, with each other. Every single interaction needs to contain a positive, such as food or play.

This process may go quickly, or it could take quite a long time. It can take days, weeks, or months. Eventually, it will pay off. You just need a little faith and patience.


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Tips for Reintroducing After a Cat Fight:

  • Do not bring frustration or negative energy to the situation. (This may sound silly, but when I got Ellie, she was having a very hard time being around Nia without attacking her. My boyfriend was constantly bringing negativity and frustration to the situation. We went along like this for 9 months. Then the cats and I moved to Florida. With the combination of an un-established territory, and calm energy, they were together and happy within less than a month.)
  • During the reintroduction process, don’t give cats food/treats without associating it with the other cat.
  • Don’t let one cat dominate one space. This means you need to trade them out, so they both have time in the sanctuary room, and in the rest of the house. Do this without letting the cats see each other. (Can put one cat in the bathroom, or another room while switching sites.)
  • Try to push their comfort zone a little farther each day. (If you observe them, you will start to see where they are comfortable, and an inch farther where they are not comfortable. Use this line to push them just a bit each time.
  • If the fights have been going on for a while, this is likely to take more time and patience than if the fight just happened, and they were immediately separated.
  • If there is a fight during the reintroduction period, just get right back to it. Even if this means starting over again. Don’t leave the cats with a negative association.
  • Manage your expectations. If your cats are tolerating one another, and not fighting, this is a good thing. Don’t get disappointed if they’re not cuddling and grooming each other for a while.

What if the Cause of the Aggression is Still a Factor?

If this redirected aggression is happening on a regular basis, then there is clearly something that is consistently triggering your kitty. Oftentimes, this is coming from a source that is outside. Maybe the neighborhood cat likes to come and sniff around, marking your yard with their scent.

Or maybe there is a scary lawn mower that causes your cat to become unhinged.

If you are already aware of the cause, you can take actions to improve the situation. For instance, if there is a particular window your cat tends to be looking out when they become aggressive, block off this window for a while. Provide them with another, better place to look out.

Put a perch or cat tree at a different window on the other side of the house. As a bonus, you can put a bird feeder or something similar outside for “cat TV.”

There are humane deterrents you can get to repel cats that come into the yard. Such as ultrasonic pest repellents (like this one) citrus deterrents (such as this one), motion activated sprinklers (like this one), etc.

If the lawn mower sets your cat off, put them into a darkened sanctuary room with gentle music and/or a fan for buffer noise. If there is a TV in the room, you can play a YouTube video for cats. These are usually videos of prey. This is one my cats love.

You can also try desensitization and counter conditioning.


My two cats laying next to each other underneath an island counter
Ellie and Nia are living proof that no feline relationship is hopeless.

Having cats that are at odds and displaying aggression toward one another can be a scary, and frustrating process. I can attest to this first hand.

But a relationship can almost always be mended. And, despite the popular rumors, cats are not actually solitary creatures. In the wild, they live in colonies consisting of other cats.

So when a cat fight breaks out, just remember:

  • Separate immediately
  • Let cats cool down
  • Check both cats for injuries
  • Test their reactions
  • Reintroduce cats at their speed
  • Get rid of the cause (if necessary)
  • Use the tips in this article!

Thanks for reading! If you have any comments, or concerns regarding aggression among your cats, please don’t hesitate to leave a comment, or contact me here. I will personally get back to you ASAP!

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Ana Melise
Ana Melise
2 years ago

You have described exactly what has been happening here at home! I am astonished with how precise and accurate your article is!!!!
We will start reintroduction just as you say!
Thanks ever so much! We are feeling a lot more confident and positive now after reading your amazing tips!
Gratitude ana and stu

2 years ago

Hi. My two cats who have lived happily with each other for nearly 2 years had a nasty bundle. They were separated immediately and we have been following the re-introduction method. They are now feeding either side of an ajar door where they look at each other but are happy to eat. The one that was the victim still sometimes growls. Can i try getting them in the same room now or should I wait until there is no growling? Also the attacker is an unneutered female (they are both female but the other one has been fixed) but she… Read more »

Reply to  Lauren
2 years ago

Hi Lauren Yes we used to have daily play with both together three times a day. We like to follow the play, “kill”, eat routine as much as possible. Since the fighting they are played with separately. They must get about an hour a day or more playtime. We were still having friendly meal times oppostite sides of an ajar door but the “Queen” has just gone into heat and the other one hissed at her at their meal time yesterday. However today they have been fine again on either side of the door. They both adore me and want… Read more »

Reply to  Lauren
2 years ago

Thanks Lauren. I’ll take all you have said on board. At the weekend, before I read your reply, we had them out together in the garden on leads. They were as good as gold. They came back into the house and were fine for 5 mins or so whilst they groomed but then there was a growl as one passed the other, so they were separated again. I can’t wait for the surgery to be over and she is healed. Hopefully that will stop the aggressive behaviour from the Queen and the other one can stop feeling so threatened. It… Read more »

Reply to  Lauren
2 years ago

Thank you for your sound advice Lauren. Before I read this we did have both cats on leads out in the garden at the weekend. They were good as gold. Sniffed each other all over, rubbed cheeks and licked each other. They still must have affection for each other. When they came back in it was only about 5 mins and the growling started so we ended it there. I will do as you suggest though until after the surgery and take it from there. The victim believe it or not is a Bengal, she’s huge compared to the other… Read more »

Laurie Lawrence
Laurie Lawrence
2 years ago
When I first brought Ellie home with two abscesses, I was actually able to heal both abscesses naturally without going…" Read more »

I would love to know how you healed abscess without a vet visit. I have paid the vet $90 TWICE in the last 6 months for outdoor cats because of facial abscess that left them lethargic
& dying. Not even my cats! One of them the vet said he wished he had filmed draining it for his channel due to how gross it was.

pauline sweeney
pauline sweeney
2 years ago

Hi, you said you would link to an article about cats who have always been aggressive towards each other. I couldn’t see the link. I have one really nervous cat that is always hissing at and starting fights with my other 2 who tolerate each other.

2 years ago

My cats were bounded from the same litter. Best friends. Almost 6 years old. One had dental surgery about 2 weeks ago and came home. Initially they were fine after about an hour home the one who didn’t have surgery attacked the one who did have surgery. I separated immediately. I’ve been trading out spaces a couple times a day. After about 2 days they seemed ok so I tried again but another fight broke out. So I started gabapentin per vet recommendation. After a few days and having a baby gate up and no problems through the gate or… Read more »

Love my kitties
Love my kitties
2 years ago

I am so glad I found this article & can ask a question! I have a situation going on that I definitely need some advice on. I brought in a feral kitten that had been living in my yard with his mother. He is a solitary kitten. I trapped both him & his mother when he was 4 months old & had them spayed & neutered. Vet said the mother is estimated to be about 6 years old now. She was done with him by age 5 months & she pretty much moved on. He was not mature enough emotionally… Read more »

Misty cole
Misty cole
2 years ago
When I first brought Ellie home with two abscesses, I was actually able to heal both abscesses naturally without going…" Read more »

My mama can’t just got into a fight with a stay cat rike at and now she’s going after her son’s witch r almost a year old she also is another of 3 kittens she bite my old man bad when he was trying to keep the apart what can I do and why is she going after her boys

2 years ago
When I first brought Ellie home with two abscesses, I was actually able to heal both abscesses naturally without going…" Read more »

Yes. The problem that I have though is the cat is a stray can and I can feed it but not touch it. Is there anything that I can put in the food?

2 years ago

Hi there! I’m so glad I found this thread. My cats are 5 and a half years old, litter mates, and both spayed girls. I’ve had them since they were kittens and they’ve never had problems. I don’t think they were ever SUPER bonded, but they played together, slept together, and never fought. Suddenly about 2 weeks ago a huge fight broke out, I was home but don’t know what caused it. I didn’t seperate them right away because it was so unfamiliar and i really didn’t think anything of it, just that someone was spooked and they’d go back… Read more »

2 years ago

Finally found some info, it’s not easy watching/hearing cats go into a fight. Leo, the attacker, and Hope(passive female)were good together for a year. All at once, the fights have started. We keep them separate when we are not around. Seems like it started when I started bringing Hope and Minmin(I have 4 rescues) outside in the Catio. I ve been trying to get Leo into a harness but it’s been a hard task. This week we were woking up at 0330 with a fight, it was awful. Leo on top of Hope and biting her. She didn’t have any… Read more »

1 year ago

Hi! We are thrilled that we just found this article!! We rescued an abandoned cat and when we took him to the vet to get neutered and shots, there was a rescued Maine Coon that had been kept in one room for his whole life without any socialization. S, the abandoned cat, is so sweet to us and the dogs. He just wants to be petted and play with the dogs. The issue is that he does not like P, the Maine Coon. P took quite a while to warm up to us. He grumbles and hisses when he doesn’t… Read more »

Alina C
Alina C
1 year ago

Thank you so much for this article. I’m facing this sad and extremelly frustrating and stressing situation. My cats eho have been living together for 4 years are having this epusode now. Your article is heaven for these unfortunate situations. Be blessed!

1 year ago

My cats had a bad fight about 6 months ago, previously best brother buddies. I’ve done the reintroduction a few times, because of another fight. The last one was at the beginning of January and I had made sooo much progress. Leaving them together whenever I’m home, but separated when I’m working. All was well until tonight when they had another bad fight. I’m so sad and disappointed, because I had planned to try full time together during my spring break in 2 wks. Now I’m back to square one. Any tips? I just love them both so much.

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