Here are the reasons why cats, from the friendly ones to brand new kittens, make that hissing sound.

If you've ever been hissed at by a cat, you'll remember: It's a scary sound. A hiss coming from a cat is similar to the warning sound a snake makes (also memorable!). In fact, some cat behaviorists suggest cat hissing may imitate the sound of a snake when they hiss. Whether coming from a cat or a snake, the sound of a hiss delivers a universal message: "back off." 

green-eyed cat hissing
Credit: tavan amonratanasareegul / Getty

Why Does Your Cat Hiss? 

While many cat noises can indicate contradictory situations (for example, purring is generally associated with cats being content, but it can also indicate fear), hissing is plain and simple. It's a warning sign. And when you witness a hissing cat, there's no doubt the cat is agitated.

There are several reasons why your cat might throw a hissy fit. Let's break them down:

Reason #1: Your Cat Is Annoyed

There are several ways a cat can show their annoyance at a person, animal, or situation. Most include pretty obvious body language like bared teeth, pinned back ears, an arched back, a fluffed out tail, or widened eyes. But when it comes to sounds, hissing is the cat noise or vocalization that indicates your pet is peeved. 

According to cat behaviorist Marilyn Krieger, Certified Cat Behavior Consultant in San Francisco (aka The Cat Coach and author of Naughty No More: Change Unwanted Behaviors Through Positive Reinforcement), when your cat hisses it means your pet is on the defensive. And you need to be aware. 

"A hiss is definitely telling you to stay away," she says. "It's a distancing behavior. It may be a prelude to aggressive behavior biting." And hissing can be in reaction to another cat or animal. "If the cat is hissing by the window, there might be another animal outside. Cats can smell a cat outside who has sprayed to mark their territory," she says. 

Reason #2: Your Cat Is Afraid

Fear is a strong reason for your cat to hiss. You've heard of the "fight or flight" response. When a cat is startled or afraid, she may react with a hiss. A hiss may be the precursor to a fight or flight, another way of saying, your cat might be having a bit of an anxiety attack.

Reason 3: Your Cat Is Confused

Cats have varying levels of comfort with new situations, and even confusion can cause some cats to spit out a hiss in response. This might pop up whenever your cat is meeting a brand new kitty, and doesn't quite know what to make of them yet.

Reason 4: Your Cat Is in Pain

Hissing might also indicate a physical problem. "If the cat is hissing for no apparent reason, the cat might be in pain," Kriegar says. If your pet is showing other symptoms of pain, like a hunched posture or unusual hiding, you should probably schedule a visit with your vet.  

What To Do If Your Cat is Hissing

Stand down. The bottom line is this: Your cat isn't happy. She is on guard and ready for the next step. Just like with snakes, a hissing sound means danger. So, obviously, it's best to give hissing cats a wide berth.