It is always with concern when we witness what seems to be angry aggression between cats who have been good buddies in the past. Two cats will be engaged in mutual grooming one minute, and at the next, are locked in a tooth-and-claw battle.
Our instinct is to break it up before someone gets hurt, and indeed, sometimes that intercession is called for. However, aggression between housemate cats comes in several forms, with associated causes, and it behoves us, their human companions, to fully understand these kinds of aggressive behavior so that we can take appropriate steps when needed.
Also called “play-fighting,” it starts at an early age with littermates, or with non-related kittens sharing a household, but is not confined to kittens. Cats have a natural instinct for survival, whether in the wild or in a cushy home, and early-on are taught predator-prey behavior by their mothers.
One kitten will “stalk” the other, then pounce his unsuspecting prey, and the fun is on. You will then see them trade-off roles, with the victim chasing his former predator.
Play-fighting is usually harmless fun. It should be mentioned also that play aggression is the first step toward establishing a permanent hierarchy, or “pecking order” among feline housemates.
Territorial aggression can sometimes arise suddenly between two relatively evenly-matched cats and can take place between male-male, male-female, or female-female.
Territorial aggression in the form of fighting is often accompanied by urine spraying or “marking,” which helps identify this form of aggression.
The aggressor cat is not necessarily the older cat, nor the one who has been in the household the longest. He will preface his attack with much posturing: back raised, ears laid back, with accompanying growling and hissing, then leap on his victim and attempt to bite him on the back of the neck.
In many cases, the “victim” cat will back down by turning and walking slowly away, and the social hierarchy process will have begun.
Other times, the victim will give tit for tat, and a violent battle may ensue.
Do not attempt to physically separate two fighting cats; in the heat of emotion, they will not recognize you, and severe injury could result. You may try one of these methods of breaking up a fight:
Most housemate cats will eventually resolve their disputes; one will reign as the “alpha cat,” and the other will be satisfied with his lesser role in the “hierarchy line.”
On the other hand, you may be faced with the dilemma of two cats who will never get along and may have to be permanently separated.