When A Cat Growls....

...well, consider it a fair warning. Cats don't usually growl, but will meow angrily instead when just generally pissed off or unhappy. Even when cats are tousling with other cats, you will generally hear those mean meows and screeches. A growl, however, indicates that the cat really feels itself to be in danger and is going into absolute defensive mode, claws out, take no prisoners. Consider that to be a level 10 and step back!