Ginger and white cat with puffy tail standing on ice

Why do cats’ tails puff up? Cat body language decoded

Have you ever seen your cat’s tail looking like a bottle brush and wondered, “What the heck is going on there?! Why is my cat’s tail all puffy?”

You’re not alone. A lot of cat owners wonder what’s up with their cat’s tail when it looks all puffy. Is she sick? Did something happen to her tail?

Wonder no more! I’m here to answer that question for you and give you some insight into why cat tails might sometimes look a little funny. Keep reading to find out more about your cat’s puffy tail!

How does a cat’s tail puff up?

Hair or fur standing on end is caused by a release of specific hormone signals from the cat’s nervous system in response to stress or trigger of the fight or flight reaction.

These signals cause the tiny muscles in the cat’s tail to contract and lift the fur away from the skin. It can extend to the muscles along the spine, causing the hair to stand erect there as well and create a ridge of fur. The technical term for this is piloerection.

Have you ever noticed goosebumps on your arms or legs? This is caused by a similar reaction in humans when we experience fear or stress. Just like with cats, hormone signals cause the muscles to contract and lift the hairs on our arms, legs, and back of the neck away from our skin.

Why is my cat’s tail puffy and what does it mean?

What does this all mean for your cat? When her tail puffs up, it’s her way of making herself appear larger and more intimidating.

Oakley demonstrates piloerection at its finest © The Cat and Dog House

4 reasons cats puff up their tails

#1. The cat is startled

When this happens, chances are there is something nearby that has scared the cat. It could be another animal, a loud noise, or even just a sudden movement.

When her tail puffs up in this instance, it’s an automatic reflex where the fight or flight response kicks in before the rational brain has had a chance to process what’s going on.

The best thing to do in this situation is to remove the source of the cat’s fear if possible and give her some time to calm down. Once she’s relaxed, her tail should return to normal. 

#2. The cat is scared or feels threatened

Cats use their puffed tail as a direct warning sign to potential predators by making themselves look bigger and appear more intimidating. They often stand sideways at the same time for this reason (think Halloween cats).

The frightened cat may also arch her back, flatten her ears, and yowl, hiss, spit or make low-pitched growls. This full-body sign of fear aims to discourage the threat or scary thing from coming any closer.

Again, remove the reason for your cat’s fear if possible, or remove her from the situation. Unless you know your feline friend very well and how she might respond, I wouldn’t recommend trying to pick her up though! She may well be too aroused and a scared cat could lash out and scratch or bite.

You could, however, try luring her away by calling her gently or pulling a cat toy or some string along the ground to try to engage her in play to counter the feeling of fear.

If she’s scared of something she’s seen outside the window (another cat in her yard, for example), you could close the curtains or blinds so she can no longer see the threat.

Black dog watching nervous tabby and white kitten walk past
Millie the kitten has never seen a dog before and is showing signs of a puffy tail as she gingerly walks past cat-friendly Roxy © The Cat and Dog House

#3. The cat is angry and (potentially) aggressive

When a cat is angry, her tail may puff up as an instinctive response to an unpleasant situation and, again, an attempt by the cat to make herself look bigger and more intimidating.

The angry cat’s tail will be straight up and again her ears may be back, her back arched with piloerection along the spine, with accompanying vocalizations such as growling, hissing, spitting, and yowling.

She may also stare directly at the interloper. Staring is a hostile behavior and a more subtle sign of aggression.

I once saw two of our outdoor cats, Curtis and Jeffrey, sit and yowl at each other on the back wall. Neither moved for several minutes. Eventually, they stopped yowling but remained sitting there, about two yards apart, staring at each other. After several more minutes of that, Jeffrey slowly got up and quietly removed himself.

Curtis, who was quite the bruiser in his heyday, was supremely confident and just remained sitting there, watching. He knew he could take Jeffrey if he had to, and so did Jeffrey. Jeffrey wisely cut his losses and moved along*.

As a rule, cats will usually only fight if no one backs down. Often, the posturing is just an aggressive bluff. It’s too risky to fight because the cat can get badly injured (e.g. minor abrasions, skin infections, bite wounds, or abscesses that need veterinary attention).

Two cats about to fight over resources
Spencer (left) wants access to the dog bed he and Curtis have commandeered for themselves but Curtis doesn’t want him there. Spencer’s tail is puffed up in a sign of defensive aggression but he is already backing off © The Cat and Dog House

#4. The cat is excited or playing

Cats sometimes puff up their tails when they’re playing or feeling excited.

This is often seen in kittens. As they get older and start exploring how to interact with one another and develop their social skills through play, you may see the puffed-up tail posture and a raised tail (or a tail shaped like a hook or question mark – a sign of friendliness) as a sign of excitement, without any other indications of aggression.

I’ve seen this plenty of times in our adult cats too when they’re just running around in the forest sniffing and having a good time. It’s a sign of emotional arousal – in this case, playful cats with positive emotions (as opposed to the negative emotional states described above).

Giner and white cat scratching tree in the forest
Oakley’s out in the forest having fun and his tail is puffed up as a sign of his playful mood © The Cat and Dog House

What does it mean if my cat’s tail is arched?

Sometimes a cat’s tail will also be arched when it’s puffed up. This can happen when the cat feels a direct threat. She may be prepared to fight, but her goal is for her opponent to reconsider their attack mode and make the decision to retreat rather than fight.

“This display can be either a sign of defensive or offensive aggression. She will also arch her back and stand very straight-legged to maximize size,” explains renowned feline behavior expert Pam Johnson-Bennett.

How do I know if my cat is stressed or happy?

To tell the difference between a stressed or anxious cat and a playful or happy cat you just need to consider the overall context and the rest of their body language in addition to their tail position.

While the context will be pretty obvious (i.e. if the cat’s scared of something or having a fun game), there are other signs to watch for too.

Understanding cat body language

For example, if the cat has erect ears she’s feeling curious and engaged in what’s going on. Her whiskers may be pointed forward and her muscles will be loose and relaxed.

If she’s feeling scared or threatened, her ears will be turned back flat against her head, and her muscles stiff and ready to spring into action.

Of course, every cat is different and you’ll get to know your own kitty’s unique quirks and personality traits over time. But those are some guidelines in a nutshell that should help you to interpret your cat’s body language.

Final thoughts

Piloerection is an important part of feline body language and communication. So next time you see your cat’s tail start to puff up, don’t be alarmed! It’s just her natural response to stress or perceived danger. Take note of the situation and try to decode what she’s trying to say.

And rest assured knowing that her tail will return to its normal state once the threat has passed or the excitement is over.

* Curtis and Jeffrey both became indoor cats who lived long and happy lives away from the heat and stresses of the Dubai streets.

READ NEXT

Resources