Behavior Health

Understanding the Fight or Flight Response in Cats

Learn what happens during fight or flight and tips for working with cats experiencing it.

The fight or flight response in cats or any living thing is obviously something we hope not to experience. However, if you adopt or foster a cat that’s been (or possibly been) through trauma, it’s important to understand. It will give you insights into strange behaviors, but it will also help keep you and your family safe. I should also add, the average cat parent will not see this behavior often. Cat foster parents or those that work in a shelter or rescue environment will see it much more frequently.

One of my cats goes into fight or flight quickly and frequently, which taught me how to work with her. Keeping her calm, happy, and content is a daily goal of mine. I hope this article is interesting for all, but I also hope it helps someone who has a cat like me understand how to better help them.

Black and white cat on cat tree
Lucy is very content in her room. It keeps her calm and helps her not escalate to fight or flight.

One last note before we dive into it. A lot of the information I’m using to write this article is based on articles written about humans. The mammalian brain, while different from species to species, has a lot of the same parts. It’s fair to assume the actual brain works similarly.

Laywoman’s Explanation of the Fight or Flight Response in Cats

First, what is a fight or flight response?

It’s when our brain prepares our body to fight or run when faced with a threat in order to survive. Here’s what happens:

  • Increased heart and respiration rate
  • Increased oxygen flow to major muscle groups
  • Decreased pain perception
  • Decreased appetite
  • Improved hearing, vision and other senses
  • Increased sweating
  • Increased anxiety

Animals use this response much more than humans since they must avoid threats in the wild, like predators, on a daily basis.

A cat needs to avoid predators and other threats in their environment. Bringing them indoors doesn’t remove this efficient response to danger.

The Steps in the Fight or Flight Response

  1. The amygdala is the part of the brain that has an automatic response to fear. It sounds the alarm that there is a threat by alerting the hypothalamus.
  2. The hypothalamus is the like control center of the brain. It helps keep the body balanced, controlling sleep, memory, and appetite, and releasing hormones. In fight or flight, it tells the adrenal glands above the kidneys to release the adrenaline (a hormone) into the blood. As a result:
    • Heart rate increases, sending more blood to muscles and organs.
    • Blood pressure increases.
    • Sugar and fat from storage enter the bloodstream, giving the body instant access to more energy.
    • Breathing becomes faster. More oxygen travels to the brain and increases alertness and heightens senses.
  3. As the first batch of adrenaline subsides, the body must continue to respond to the threat. The hypothalamus produces corticotropin-releasing hormone (CRH) that reduces hunger and increases anxiety.
  4. When CRH reaches the pituitary gland (part of the brain that makes hormones to regulate growth, metabolism, blood pressure, and reproduction), the hormone adrenocorticotropic hormone (ACTH) is released.
  5. Once ACTH reaches the adrenal glands, they release cortisol, known as the stress hormone. Nearly every cell in the body has cortisol receptors. Cortisol helps:
    • Pump blood harder and faster to the heart and large muscles.
    • Trigger the release of glucose to supply energy to large muscles.
    • Slow digestion so glucose is available for use and isn’t stored.
  6. As the threat disappears, it can take 20-60 minutes to come out of fight or flight as cortisol decreases and the body returns to normal.

To learn more about the fight or flight response, read my sources Understanding the Stress Response (Harvard Health Publishing) What Is the Fight-or-Flight Response? (by Kendra Cherry, VeryWellMind).

What to Do If Your Cat Is in Fight or Flight

If a cat is experiencing a fight or flight response, keep in mind that they will not recognize you. Their only goal is to survive and get out of the situation they’re in. I don’t recommend handling a cat, especially if they appear ready to fight. The cat may hurt you. Even though your cat loves you and wouldn’t normally do that, they are operating on autopilot for survival.

The best thing to do is get away from the cat and let them cool down. In most cases, you should be able to just walk away. Don’t touch or engage with them until they are back to normal.

In more extreme cases (which are rare):

  • Close them in a room for an hour or two and allow them to calm.
  • If you feel you are in actual danger and the cat is going to attack, do your best to block your body with an object or throw a towel over the cat so you can get away.
  • After a bad fight or flight response, it can take days for the cat’s brain to actually return to normal. For the next few days, the cat is more likely to have another episode (the initial incident lowers their threshold). Do your best to behave normally and keep the environment as calm as possible.

Fight or Flight Is in Response to PERCEIVED Danger

Fight or flight isn’t just present in the face of something that’s actually dangerous: It exists in the presence of something a living thing perceives as dangerous. In these cases, the amygdala signals a false alarm. Humans can go into a fight or flight over public speaking, which is not actually dangerous. I go into it over spiders, even ones the size of a dust particle. Although a situation may not be dangerous, if the animal perceives it as such, they can go into fight or flight.

The Impact of Repeated Stress on the Fight or Flight Response in Cats

A neglected or abused cat will likely go into the fight or flight response at a higher rate than one that is not. This can have a permanent impact on the brain and change how it responds to stress. It’s believed that over time, the hypothalamus is more easily stimulated (because it’s in a heightened state so frequently). The amygdala goes from sounding false alarms rarely to making it commonplace. The result is a cat with an increased fight or flight response in the presence of seemingly normal situations.

Case Study: Lucy

If you want to see a fight or flight response in cats running wild, look at my cat Lucy. Before I met Lucy, she suffered years of neglect and abuse. Everything upset this cat. Simple things like me scratching my nose or crossing my legs resulted in growling and hissing, and sometimes biting.


Normally a cat like Lucy would be put on SSRIs like Prozac or Paxil, but Lucy didn’t respond well to them – they made her worse. We settled on giving her gabapentin 2x daily (and have since gotten down to 1x), and I focused on creating an environment that would work for her.

Environment & Routine

Black and white cat on wheel
Lucy walks on her wheel frequently throughout the day. I think it helps her get exercise and also decreases her anxiety (like exercise does for people).

She lives in her own room where every day is calm and predictable. Her room has a giant cat wheel, cat tree, cat shelves, window perch, tunnel, cat bed, plenty of toys, wall-mounted fireplace, TV, and couch. I don’t allow other cats in her room. Sometimes I’ll take her for walks at the park, but I make sure we do the same things every time (walk the same direction, stop at the same spots, etc.). My goal is to keep her below the threshold of getting upset, because once she’s upset, it’s a wrap.

If Lucy doesn’t get her gabapentin (once every few weeks her mood is terrible in the morning), she doesn’t eat much. I knew this was tied to her anxiety, but didn’t realize until I wrote this article that it’s possibly related to an increase in cortisol.

It Still Happens

On the rare occasions Lucy walks out of her room (she usually has no interest in leaving), she goes into fight or flight and I can’t touch her. She will run to the basement, growl, hiss, spit, and lunge. I’ll wait for her to go back to her room on her own. If she doesn’t, she’ll get exhausted and I’m able to corner her with a carrier, and then take her back to her room.

Lucy went into pretty bad fight or flight in the summer of 2022 when she got out of her room.

One Happy Kitty – Most of the Time

When Lucy is in her room, for the most part, she’s extremely happy. She will even cuddle with me, purr, and fall asleep. But if I move and she doesn’t like it, growls and hisses emerge. She’s a quirky girl, but I love her to pieces, and I’m glad I was able to build a life for her where she feels safe and loved most of the time.

Black and white cat nuzzling woman's head
Lucy and I have a special bond.

Extreme Situations

Although I’ve figured out a way to live with Lucy, there isn’t a solution for all cats (or pets) with this issue. It’s extremely important to take into account the welfare of 1) the animal and 2) the humans and other animals lives with. If fight or flight cannot be managed or aggression is off the charts, there is likely an issue with the hypothalamus and the kindest option is euthanasia. It is not safe to continue trying to work with an animal like this.

At the same time, we must be kind to people who must make the difficult decision to euthanize a pet or foster because of aggressive and uncontrollable behavior. I have had to do this, and it absolutely ripped my heart out. I’ve spoken with people who had to do it, and it is not something pet and animal lovers want to do. When you cannot safely be in a room or even outside with animal, you cannot help them. And what type of life is it for an animal to not be able to control their fear response? Maybe some day we’ll have to tools to help them, but we are fairly limited right now. If medications and training are unsuccessful, we need to show the only kind of love we can, which is to end their struggle.

Black and white cat
Lucy is a sweet, happy girl most of the time.

Fortunately, most animals have an efficient fight or flight response, and this isn’t an issue. Again, my goal with this article was mainly to educate, but also help people who encounter difficult animals. You are not alone, and I hope this article helps you understand a little more about the fight or flight response in cats so you feel better equipped to handle it.

By LizsKittyBootCamp

Hi, I'm Liz, and I'm a cat behaviorist who provides advice and insights on cat behavior.

5 replies on “Understanding the Fight or Flight Response in Cats”

Thank you so much for taking the time to share your experience ,, our cat cammy had kittens 8 weeks ago no problem 4 beauties !! My husband accidentally stepped on of the kittens paw and it screamed !!! Our cat that we vod bath , take for drives , never aggressive slept with my husband and the kittens ,,, became severely aggressive attacking my husband even sought him out and attacked him again !! She does not seem to be remotely the same cat !!! We were literally held up in our bedroom to keep from being attacked the third time … numerous scratches blood all o er , she was incontinent of feces during the attack ,, our son in law helped us get her in a room with her kittens ,, we put food water and litter box in room very quickly ,, turned on calming music,,, we are broken hearted … this article helped so much thank you

I’m sorry that happened to you. Hopefully after she calms shl be better

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