My cat is aggressive: why it attacks and what to do in each case
There is no such thing as a bad cat. A cat that hisses, scratches or bites has a reason, and that reason is most often fear or pain. Working out which type of aggression it is matters, because the fix for one can make another worse. And if the aggression has appeared suddenly, the first step is the vet.
If it has appeared suddenly, vet first
A calm cat that suddenly starts hissing, scratching or biting almost always has a physical reason. Pain is the most common medical cause: arthritis, which is badly underdiagnosed in older cats, dental problems such as resorptive lesions, wounds, infections or abdominal pain. Hyperthyroidism, very common from the age of ten, makes cats irritable and restless. Neurological problems, loss of sight or hearing and cognitive decline also change how they react to being touched. Before looking for a behavioural explanation, get a full check-up at the vet and tell them when it started, in what situations it happens and whether there have been other changes in appetite, litter tray use or activity.
Fear aggression
This is the most common type. A frightened cat would rather flee, but if it cannot, because it is cornered, held or somewhere with no way out, it defends itself. The signs are clear if you know how to read them: a crouched or side-on body, flattened ears, dilated pupils, raised fur, hissing and growling. It is the typical aggression at the vet, with unfamiliar visitors, with children who chase it or with a dog. The solution is to remove its need to defend itself: do not corner it, always give it an escape route and hiding places, do not force contact, and work gradually on whatever frightens it, always with positive experiences. Punishing it for hissing makes the fear worse and takes away the warning.
Play aggression
This is the young cat that pounces on your ankles, grabs your hand while you sleep or ambushes you from behind a door. There is no fear here, it is hunting: the body is crouched, the pupils dilated, the bottom wiggles before the pounce and there is no hissing. It is very common in young cats living alone, with no other cat to play with, and in those that have learned that hands are prey. The solution is plenty of interactive play with wand toys and other toys, two or three sessions a day of 10 to 15 minutes, never playing with your hands and, at the moment of the attack, keeping still and becoming boring. In some cases, a second young, compatible cat helps.
When it bites while you stroke it
The cat is perfectly content and then, suddenly, it bites. This is called petting-induced aggression, and it is more a matter of overload than aggression. Every cat has a tolerance threshold for contact, and past that point it feels overstimulated. It does warn you first, but subtly: the tail starts thumping, the skin on its back ripples, the ears rotate backwards, it stops purring or turns its head towards your hand. The solution is to learn those signs and stop sooner, stroke the areas cats tolerate best, which are the head, cheeks and chin, and keep strokes short, letting the cat ask for more. Over time, many cats tolerate a bit more contact.
Redirected aggression, the most baffling kind
This is the one that frightens people most, because it seems to come out of nowhere. The cat sees another cat in the street through the window, or is startled by a noise, or gets very worked up about something it cannot reach, and it releases that tension by attacking the first thing nearby: the person walking past or the other cat in the home. Sometimes the attack is violent. If it happens, do not try to pick up or calm the cat: step away, leave it alone in a quiet, dark room and wait for it to calm down, which can take hours. If the attack was on another cat in the home, it can break their relationship, and you will need to separate them and reintroduce them gradually. And block the view from the window that triggers the problem.
Aggression between cats in the home
Two cats living together can fight for several reasons: an introduction that was too quick, one of them reaching social maturity, between two and four years of age, competition for scarce resources or an episode of redirected aggression. There are not always open fights: sometimes one cat blocks the way to the litter tray or the food and the other lives cowed. The basis of the solution is the same as for any multi-cat home: separate, plentiful resources, meaning food bowls, water bowls, litter trays, scratching posts, beds and high spots in several areas of the home, so nobody has to compete. If the fights are serious, separate them and do a slow reintroduction, as if it were the first time.
Territorial and maternal aggression
Some cats react aggressively to a new cat coming into the home or to outdoor cats approaching the windows or door. It is their way of defending territory, and it often comes with urine marking or extra scratching. Visual barriers on the windows, keeping outside cats from coming close and a very gradual introduction of any new cat help a great deal. Maternal aggression is that of a queen who has just had kittens and is defending the nest: it is normal, temporary and resolves by leaving her in peace with her litter, without handling the kittens more than necessary in the first weeks. Neutering cats greatly reduces hormone-related aggression.
What you should never do
With an aggressive cat, punishment is the worst possible response. Shouting at it, hitting it, spraying it with water or restraining it increases fear and stress, which are at the root of most aggression, and teaches it that people are dangerous. What is more, if a cat is punished for warning with hisses or growls, it may stop warning and go straight to biting. Nor should you try to separate two fighting cats with your hands: it is the surest way to end up with a serious bite. Use a barrier, such as a cushion, a blanket or a board, or a loud noise to interrupt the fight, and then separate the cats into different rooms.
If it bites you: take care with the wound
A cat bite that breaks the skin is no small thing. Their fangs are thin and long and deposit bacteria very deep, and a high proportion of these bites become infected, sometimes within a few hours. Wash the wound immediately with plenty of soap and water for several minutes. If the bite is on the hand, on a joint or near a tendon, if it is deep, or if in the following hours it swells, turns red, hurts or you notice a fever, see a doctor that same day, because it may need antibiotic treatment. Also check that your tetanus vaccination is up to date. Deep scratches can become infected too and should be washed well.
When to get professional help
If the aggression is frequent, intense, getting worse or you do not understand what triggers it, and the vet has ruled out medical causes, consult a vet trained in clinical behaviour. They will ask for a detailed description of the episodes, the home and the routines, and will design a plan that may include changes to the environment, behaviour modification and, in some cases, supportive medication, always prescribed by them. It helps a lot to keep a diary of each episode: what happened just before, where, with whom and what the cat's posture was like. A video is worth a thousand explanations. Most cases of feline aggression improve greatly once the cause is understood.
A cat is not aggressive for no reason: it is almost always fear, pain, misdirected play, petting overload or redirected aggression. If it appears suddenly, vet first. Never punish, and never separate fights with your hands. Provide escape routes, separate resources and play. And a bite that breaks the skin, especially on the hand, needs a doctor if it becomes inflamed.
Educational content from Michipedia, translated from the Spanish original. It does not replace the advice of a vet or a feline behaviour specialist. Every cat is an individual.