It's easy to confuse cat playing with aggression -- after all, young felines are famous for playing rough. Despite all the drama in their mock battling, hissing is generally reserved for only two kitty emotions: fear and anger. If a cat is hissing at you, he's not playing around.
Hissing is not a typical component of feline rough play. However, cats do often employ play techniques that resemble fighting actions. Young kittens learn crucial developmental and social skills by playing with their littermates. Their playing style is joyfully rambunctious, with the little cats gently or not-so-gently biting, swatting, pouncing and chasing each other. In such early interactions, cats learn boundaries. For instance, if a kitten bites just a tad too hard, his victim might stop playing or might retaliate -- lesson learned. Some cats continue their rough-and-tumble style of playing well into adulthood.
When a cat hisses, don't mistake what he is doing as playing. He may actually be sending you a clear warning or perhaps a threat. He's furious about something and wants you to go away. If you -- or whoever else may be upsetting the cat -- don't immediately scram, the cat may bare his teeth or claws. In these situations, a hissing cat can be extremely dangerous. Give him the space he wants. Approaching a hissing cat may be seen as a type of provocation.
A cat's hiss doesn't have to be an overt act of aggression. It can be an indication that the cat is frightened and wants to protect himself against you or whatever he perceives as being his predator or problem. The cat may think that someone or something is trying to harm him and is acting instinctively out of self-preservation.
A hiss can signify mild irritation or annoyance. If you attempt to pet a fluff ball's back and he responds with a hiss, he may be feeling overstimulated. He simply doesn't feel like being social at the moment.
If a hissing cat does indeed end up scratching or biting you, don't just ignore it. Cat scratches and bites can lead to harmful infections -- think cat scratch disease and rabies. Be on the lookout for key signs of infection, including headache, exhaustion, unusual itchiness, disorientation, irritability and red bumps on the location of the scratch or bite. Upon noticing any abnormal symptoms at all, waste no time in heading to the doctor's office or emergency room.