Aggression/Anxiety/Fear Behavior

Uncontrollable Aggression in Cats: The Story of Linux

The difficult story of feline aggression that couldn’t be controlled.

Linux was a beautiful orange tabby with energy that rivaled any domestic cat I think I’ve ever been around. He was affectionate, loving, and obsessed with playtime. But, he also had a dark side: Anxiety bursting into uncontrollable aggression and rage as he delivered kill bite after kill bite to people helping him, including me.

I’ve struggled with telling this story because the ending isn’t what I hoped or worked for. But ultimately, detailing such a rare and extreme case of aggression is a learning experience for all of us. To not discuss it just keeps it hidden as if Linux and cats like him are a problem we shouldn’t talk about because it’s uncomfortable. Welp, I’m going there anyway. I’m proud for loving him and trying to help him. Even though I didn’t help him become a more balanced cat, I did give him a gift: Freedom from an anxiety-ridden life and an overstimulated brain that he could never escape from. This is the story of Linux.

DISCLAIMER: There are graphic pics below of cat bites.

Linux’s Pre-Boot Camp History

Honestly, we don’t know a ton about Linux, except that he lived in the basement of a deli in NYC, with at least one, but possibly more, cats. At an estimated 2 years old, he was neutered and transferred to a no-kill rescue, where he’d wait for adoption.

Orange cat on gray bathmat
Linus relaxing in my bathroom. He was such a handsome boy.

Once he started repeatedly and viciously attacking staff, the rescue abandoned the original plan. Cats that bite are put on a 10-day bite hold each time, and kept in a kennel with limited interaction. With a team of behaviorists and animal welfare experts, the group tried to work with him and find the trigger for his aggression, even putting him on Prozac with the hope it would calm him enough to work with him. They were unsuccessful, and the SSRI medicine didn’t appear to do anything.

The last straw came when he left 40 puncture wounds on someone’s leg and the only way they got him to stop was by putting a scratcher between his biting mouth and leg.

orange cat with toy mouse in mouth
Linux loved to catch toy mice and feathers and carry them around.

A rescue contacted me as a last resort. I read detailed notes of Linux’s previous attacks. They sounded severe and intense, and I was a bit scared. I said I’d help under one condition: If I couldn’t make progress or if I was getting attacked, we’d need to look at his quality of life and possibly make THE decision no one wants to make.

Boot Camping

Linus arrived at boot camp and I put him in one of my bathroom with tons of toys, and added three doses of 100 mg of Gabapentin each day. I noticed immediately that his energy level (and likely his anxiety) were through the roof. He quickly tore apart the bathroom, breaking things and pulling hair products out from the vanity. My bathroom looked like the aftermath of a college party.

Ankle with bite.
First attack on my ankle. Urgent care cleaned it up pretty good.

I would go into the bathroom, sit on a closed toilet and play with him using a wand toy. He seemed to love it. One evening, while playing, he suddenly stopped, smelled my foot, made a horrendous noise, and constricted his pupils. I knew he was going to attack, but I had no option. I had to just let it happen. If I tried to run, it would be worse. I watched him as he bit my right ankle twice, and the blood starting coming out from the fang wounds.

Cat bites almost always get infected, so the doctor prescribed oral antibiotics. I had a hard time walking for nearly a week until the swelling went down.

New Digs

I decided there just wasn’t enough space in the bathroom for Linux, so I set up a playroom for him in my unfinished basement. It had everything he needed: a cat chute, tree, wheel, and lots of toys. I started playing with him 1.5-2 hours a day, and each session I made him run, jump, chase, and catch toys. He eventually tuckered himself out, and would be breathing heavy and laying down.

I still knew there was something off about him, and reached out to a behaviorist. My goal was to make sure I was doing everything possible to help him, as well as figure out what the goal was. Adoption into a home wouldn’t work, but maybe a barn situation would. But would that be safe for him, any people who lived at the barn, and other animals?

Orange cat with feather toy in mouth
Linux with one of his favorite toys.

One morning, we were playing, and he suddenly stopped. I knew how this was going to go. The sound came. The eyes constricted. I threw the toy across the room, which normally would distract any cat, but not Linux. I held up my boot, and he attacked it, biting THROUGH the boot. How was that possible. This was a cat. I had never seen that level of aggression before. I was so glad that my appointment with the behaviorist was the following day.

Anxiety & Aggression Overload

That night, I went into the basement to give Linux his last meal of the day. He was disinterested in food, so I played with him. It took only a minute or two before I saw the warning. The nose smelling, loud meowing, constricted pupils, and then, he lunged. He was viciously biting my legs so fast and furiously, I didn’t even know what to do. I was yelling and begging him to stop.

I grabbed a very large carrier that was close by, put it between us, and opened the door. He ran out of the basement, into the house, and I closed the door. Looking at my left wrist and right leg, decorated with bleeding fang marks, I started crying, not because of the pain, but because I knew, I couldn’t do this anymore. I couldn’t fix Linux way I wanted to.

I honestly don’t know how I got out of the basement and got Linux back in the basement. It’s a total blur. After an urgent care visit, I picked up antibiotics and realized I had to somehow get Linux into a carrier. I lined up a large kennel with carriers on either side and on the top. Then, I used a large piece of wood leftover from my kitchen reno as a shield. Thankfully, it only took a few seconds to get him into the kennel.

Rainbow Bridge

As I entered the animal hospital, I burst into tears, telling Linux’s story and showing my wounds. Everyone was so understanding and comforting, explaining that I did everything possible, and sometimes something is just wrong.

paw pads
Linux had very big paw pads. This was given to me the night he was put to sleep.

The staff had to sedate him first to make sure it was safe for everyone. Then, they gave him to me, and I spent 10 minutes one-on-one talking to him, apologizing, and crying. When it came time, the vet came in and administered the euthanasia drug. Just like that, Linux, the big beautiful orange tabby was gone.

As I drove home, I just kept crying. I felt like such a failure. When I arrived home, I opened the card the animal hospital staff gave me on the way out. Normally, it’s full of many “I’m sorry for your loss”-es. This time, it was full of personalized messages about Linux and me, which gave me so much comfort when I needed it.

Understanding Aggressive Behavior

In the morning, I felt quite defeated when I met with the behaviorist, but it ended up helping me get my head on right. Dr. Karen Overall has helped me understand what I’m seeing over the years. She diagnosed my cat Lucy with impulse control aggression, and talking with her opened up my eyes to the pathology and how it impacts cat behavior.

What was Linux’s diagnosis? Predatory aggression, play aggression, and impulse control aggression. What was wrong with him? Impulse control aggression to the extreme. In these extreme cases, which are also thankfully extremely rare, the best thing for the cat and people around them is usually euthanasia. There is no safe way to interact with them (remember, my boots couldn’t protect me). In some instances, cats may end up living in a room at a sanctuary with two levels of doors to gain entry. The quality of that type of life is questionable. My cat Lucy has a more mild case than Linux and it’s managed with medication, routines, and acupuncture.

Black and white cat walking on wheel
Lucy manages her stress and anxiety with gabapentin AND physical activity, like her cat wheel.

The easiest way to compare Linux to us is to imagine blind rage. Many people don’t remember what happened during a moment of blind rage, and that’s sort of what happens with cats in these situations. It’s fight or flight. They aren’t seeing the person or victim they are attacking. It isn’t personal. But what causes attacks? It all happens in the brain.

Orange cat in unfinished basement
Linux is waiting for the next wand toy to come his way.

Studies show that the hypothalamus is the part of the brain responsible for aggression and it’s where the attack mechanism occurs. When stimulated during studies, cats exhibited the exact type of aggression as Linux. Something else interesting, the hypothalamus is part of the limbic system, which is also responsible for emotions, memories, and processing smells. This would explain why Linux would smell first and then get aggressive, and why many cats can have a negative reaction to smells. The hypothalamus is also related to the trigeminal nerve which controls the opening and closing of the jaw. This explains why Linux would deliver kill bites instead of swatting. He was simply doing what his brain told him to do.

Causes for Aggression

What caused Linux to have these issues in the first place? Why was his hypothalamus not working correctly? There are so many possible causes, and the truth is, we will never know. Usually, something happens to the brain before it matures at 2-3 years of age, but some conditions can happen at any time and impact the brain. Here are a few possible events that caused Linux’s hypothalamus to not work correctly.

  • Experienced starvation or social deprivation during brain development (can contribute to increased preservation and decreased behavioral flexibility)
  • Experienced neglect or abuse before brain matured
  • Sick mother while Linux was in utero or Linux was sick as kitten, affecting nutrition needed for healthy brain development
  • Weaned from mother’s milk too early, impacting brain function or leading to higher dopamine and lower serotonin levels
  • Brain tumor
  • Partial seizures
  • Damage to temporal lobe, including hippocampal formation or amygdala

Internal Anxiety

Now, let’s consider the impact of aggressive attacks on the cat. Studies have shown that the cat is reactive for 2-3 days after an incident. That means the brain is in a heightened state, which most likely feels like a high level of anxiety. It also explains why Linux attacked my boot in the morning and my body at night. The threshold is lower once an incident happens. The more it happens, the lower the threshold becomes, and the more dangerous it is for those around the cat.

But also, let’s think about the cat. What kind of life is it to be in a nearly constantly state of fight or flight?

Success Looks Different

orange cat on stratcher
Linux looking super dapper.

Instead of looking at failing Linux, I changed my approach to that of saving him. I didn’t give up on him. He was well-fed and cared for. We worked together through meds and play to try to decrease the activity in his brain to a healthy level, but we couldn’t, because there was just something wrong. He needed to be set free. Although I wish the outcome was different, I’m glad I was the one to give that gift to him. I’ll never forget him.

Learn More

If you have a cat suffering from aggression, make sure you never put your or anyone else’s safety at risk. Work closely with a behaviorist to determine the right combination of traditional medicine and non-traditional options to help your cat. To learn more, read my articles on Gabapentin and acupuncture.

By LizsKittyBootCamp

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

8 replies on “Uncontrollable Aggression in Cats: The Story of Linux”

I came here because our orange tabby whom we rescued when he was a tiny kitten, viciously attacked me 2 days ago. He is currently being segregated from myself and our other cats. It hurts because I feel like euthanasia will be our only option. We are currently talking to someone about what we can do but after reading this story, we may have exhausted everything. I am now also terrified of him . 😦

I’m so so so sorry to hear about what you’re going through. It is just so heartbreaking for everyone involved. There are a lot of medicines you can try and other therapies, but if it’s unsafe to even give the cat medicine, then that isn’t an option. If you’re able to consult a behaviorist, they can probably tell you what you can try as well as hypothesize what’s going on with him. The latter I found helpful with Linux, and it made me feel even more sure I made the right choice. Whatever decision you make, it’s the right one. Again, I’m so sorry you’re going through this.

I came here because our orange tabby whom we rescued when he was a tiny kitten, viciously attacked me 2 days ago. He is currently being segregated from myself and our other cats. It hurts because I feel like euthanasia will be our only option. We are currently talking to someone about what we can do but after reading this story, we may have exhausted everything. I am now also terrified of him . 🙁

[…] Rage is out of control aggression, that includes frenzied attacks with repeated kill bites (four fangs into the skin) on humans or animals. Typically, these cats can’t stop themselves and are responding to signals in their brain (aka it’s not personal). Although rage isn’t common, it does exist, and you can read about my experience with Linux and rage. […]

I have an Orange and white tabby who is now 18 months old. He was very sick when I got him and his sitter from a rescue at 3 months old. I think the trauma of all he went through to keep him alive has really messed him up and caused a tremendous amount of anxiety and behavior issues. I keep being told to get rid of him, but I love him dearly and want so badly to help and keep him. I have 2 other cats, which complicates my scenario. If you happen to read this comment and would be willing to talk with me via email and/ or Facebook messenger, or even the phone, and possibly give me some advice/pointers/help I would be more grateful than you can imagine!! There are a lot of issues finding homes for cats I our area, let alone a kitty with some special needs. I worry that if I try to regime him there will be issues or he’ll just be dumped at the shelter with a very poor ending. Please help if you can!!!

Hi Bonnie. I sent you an email. If you don’t see it, check in your spam folder.

My heart is breaking even more reading your story. I have a 4 yr old ginger cat Mango and 2 years ago he viciously attacked my dog as he got startled so we learnt to do everything not to spook him he was great until a few months later and he did it again when my other cat spooked him so mango attacked my dog again drawing blood all over his head, mango was always so loving after like he never knew what he had done. It’s seemed to get more frequent and always at my old dog until one night a picture fell off the wall in my bedroom whilst I was asleep and as I sat up he went for my head and didn’t stop I had to scream for help and my daughter woke and ran in and got him away, I ended up with a bruised eye lip and many puncture wounds in my head and back with the most severe one on my scalp needing 7 stitches. I just love him so much and knew ihw didn’t mean it he got spooked so that was just 2 months ago and he has since got my dog another 2 times medication doesn’t seem to work or even have time to work as he has done it again the past 2 days that now we have to keep him separated from being around my dog I just can’t trust him as his angry eye don’t disappear as quick. He is so smoochy and loving then just snaps. I honestly know now after reading your story our only option is to euthanise him and it’s just breaking our hearts so much. We just can’t live in fear anymore I just wish he can be fixed.
I just can’t deal with the idea of him not being around anymore. 💔💔💔💔

Hayley, I’m so so so sorry for what you are experiencing. It’s heartbreaking. Sometimes there are things wrong with their brains that we can’t fix:-( You have certainly done all you can to give Mango a good life. I’m sorry you’re faced with this decision, but it sounds like it is the best and safest thing for everyone. Thinking of you and sending a giant hug.❤️

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