Aggression between cats

Aggressive responses seen in pet cats are closely related to the natural behaviour of the species and are a normal part of predation, play and social conflict.

As a self-reliant species and solitary hunter the cat avoids physical conflict as a threat to survival, as any overt fighting could cause injury, inability to hunt and consequently death. The cat’s communication system: vocalisation, body posture, facial expression, scent marking, is used primarily to avoid conflict and diffuse tension, however, fighting will occur if the particular circumstances dictate that as the only option or even possibly when the aggressor is confident that the opponent will not retaliate.

There are a number of reasons why aggression will take place between cats, either within the home or in territory outside. Most cats will attempt to defend their home range, or at the very least the area they consider most significant to them, against invasion by others. Assertive cats in the neighbourhood may actively seek out opportunities to extend their territory and less confident cats represent easy targets. If cats are unable to or unsuccessful in the defence of their range then they could potentially become housebound as their boundaries have been pushed back so significantly that trips outdoors become too dangerous.

The cat flap or even an open door or window could potentially allow strange cats to invade the home and this can lead to aggressive behaviour from both parties. Surprisingly there are occasions when the invading force gets no opposition from the resident cat, but this is probably largely down to fear rather than a positive acceptance of the encounter. Any such invasions can also cause friction between members of the same cat household as it raises their anxiety and may potentially exacerbate rumbling tensions that have previously been maintained at a tolerable level. The sheer volume of cats in the neighbourhood can also have a similar effect as their presence becomes a pressure that they are powerless to overcome.

In disputes between incompatible cats within a multi-cat household kept indoors the same type of antagonistic interaction may take place and individuals become reluctant to venture out of one room except at very specific times as their territory becomes subdivided by the more confident cats. Active aggression (fighting) will occur if escape and avoidance opportunities are limited or absent. Some cats resort to active aggression quicker than others, dependent on their genetics, sex and early experiences.

Any household with breeding females may also experience episodes of aggression, particularly when queens are protecting their kittens. These environments can be hotbeds of tension, often displayed passively, as there is frequently a mix of entire and neutered cats. Females coming in and out of season within the group can put further strain on relationships. 

Are some cats just more aggressive than others?

Aggression is not a diagnosis or a description of a cat’s temperament but a consequence of an emotional state. Certainly some cats may be more likely to be aggressive under challenging circumstances than others.

How can I recognise aggression between my cats, is it always about fighting?

Cats are very adaptable and they can share space in a home without having that important mutual bond. If there are several cats they may form cliques or splinter groups and cohabit by appearing to 'agree to disagree' and avoiding each other whenever possible. This doesn't mean that there won't be times when aggression is evident between members of separate factions to reaffirm who gets access to a particular resource at any specific time. This is when a cat may well employ passive bullying as a highly effective tactic of psychological rather than physical warfare.

Within any multi-cat group there will be potential bullies; all they need is a victim. A 'victim' is any cat who responds dramatically and with obvious apprehension to the posturing and threatening behaviour of another. The more the cat responds to this form of intimidation, the more the bully will 'up the game'. Some of the more determined types do not stop short of driving their victim from the home. These victims are the cats that develop stress-related illness as a result of the constant, unavoidable threat that the bully represents. You may recognise the signs of bullying, for example, staring, claiming resting places or access to your lap by physically pushing another cat away, pouncing on a cat while asleep, blocking thoroughfares, sitting directly in front of the cat flap to deny entry/exit or blocking access to an indoor litter tray. This can often be very subtle as the cat only needs to position itself somewhere between the other cat and the resource to block access; to the casual observer this just looks like a cat having a rest in a perfectly harmless location.

What’s the difference between play fighting and the real thing?

Many bonded cats enjoy play fighting and will chase each other, roll around and bat each other with their paws. Play fighting is often silent, with plenty of gaps in between as each cat repositions itself. The biting is gentle and causes no injury or pain to the recipient and the claws are usually retracted. There is no reason to break a play fight if it continues at this level. Play fighting can, on occasions, escalate and any hissing or screeching could indicate that one is getting a little too rough for comfort. There will also be a rapid recovery to normal after play fighting and no obvious tension between the pair at other times.

How can I stop my cats being aggressive towards each other?

Inter-cat aggression in a household can potentially be managed by identifying the primary trigger and attempting to remove it. If the trigger is tension between members resulting from their incompatibility or constant competitive challenges, then the environment can be adapted to include additions that may limit the need for such constant conflict. It has to be remembered that these may well have become incompatible cats and re-homing one or more should not be ruled out as it could be the kindest option for all concerned, however that doesn’t stop you trying to achieve peace.

There is no ‘quick fix’ for aggressive behaviour and the best advice is to contact your veterinarian to discuss a referral to a behaviourist. You may find it useful also to follow this general advice. All ‘cat resources’ (feeding areas, water bowls, litter trays, beds, toys, scratching posts, high places to rest and private places) should ideally be provided in the formula ‘one per cat plus one extra, positioned in different locations’ to ensure all members perceive them to be in plentiful supply. If you have accurately identified separate social splinter groups, such as a couple of cats that have clearly paired up, and space is limited within the home then ‘one per social group plus one extra’ may be sufficient.

Part of the cats’ normal dry food ration can be distributed to a number of new permanent feeding ‘stations’ to give a sense of abundance and enable the cats to consciously decide an appropriate time to feed. Wet food can also be distributed in this way by providing frequent smaller meals to avoid competition at set mealtimes. The bowls should be positioned in such a way that each cat can eat without the need to turn its back on a potential adversary. Water is also an important resource to cats and several bowls placed in different locations throughout the home, away from the food, will potentially encourage the cats to visit more frequently.

Even if the cats have access outdoors it is wise to provide indoor litter facilities. If there is any bullying going on outside in the territory then it gives them the option to toilet in comparative safety indoors. If it is practically possible the provision of two separate entry and exit points to a property, i.e. cat flaps, doors or windows, avoids the risk of guarding or blocking, enabling even the most timid cat to get in or out unhindered.

Scratching posts should be located near entrances, beds and feeding stations to ensure an appropriate surface is available in areas of potential competition as cats will often scratch when others are around as a means of communicating territorial rights. Cats often prefer to observe activity from a high vantage point as this gives a strong sense of safety so plenty of opportunities to reach high places should exist. Private places must also be considered as every cat requires solitude and a safe place to rest, away from the risk of attack. Warm beds are also worthy of defence so the appropriate number should be available to avoid disputes.

My cats have suddenly started fighting, what should I do?

If the inter-cat aggression manifested itself in intense fighting between two individuals then the safest option is to separate them into different rooms for 24-48 hours until they have both calmed down. If a re-introduction at that stage still results in active fighting it may be necessary to segregate them for a longer period and treat them like complete strangers meeting for the first time. (click here for information on introducing a cat to a cat).

Episodes of aggression can occur at the most unlikely times when owners are often ill-prepared, one typical example is the reaction of the group to the return of a single member from a trip to the vet’s surgery. Cats communicate predominantly using their sense of smell, and the familiar communal odour that a group of cats create helps to bond them. That scent changes when one cat takes a trip to the vet and acquires a mix of threatening and unpleasant smells from the surgery. This can cause a dramatic response when the cat is brought home and the others fail to recognise their companion. To avoid this happening to your cat family, keep the returning cat in a separate room initially for at least the first twelve hours (or overnight) to enable it to groom to re-establish a familiar odour. You can assist this process by stroking and generally giving affection but be careful not to over fuss a post-operative patient. Be guided by the veterinarian or nurse who will give you the appropriate aftercare advice.

Why did my cat attack its companion when it saw a strange cat through the window?

Cases of re-directed aggression from one cat to another, triggered by an acute sense of threat from an external source, are also relatively common if there are underlying tensions. Cats have a very keen survival instinct that utilises an internal system referred to as the fight/flight mechanism that releases adrenaline, pumping the muscles full of blood, to prepare the body for danger. This massive emotional response can be triggered by a sudden sound or movement or the sight of another cat through a window but the ‘attack’ may be accidentally launched towards an innocent cat if they happen to be in the wrong place at the wrong time. Relationships between two cats in a household can be irretrievably damaged under these circumstances. Once again, the advice is to separate them into different rooms for 24-48 hours until they have both calmed down. If a re-introduction at that stage still results in active fighting it may be necessary to segregate them for a longer period and treat them like complete strangers meeting for the first time. (click here for information on introducing a cat to a cat)

If I introduce another cat to my existing one, will they fight?

Any additions to existing cat groups can trigger aggression as it is perfectly normal for cats to resist the introduction of others to their ‘colony’, particularly if the newcomer is a mature adult.

My cat is being beaten up by another cat in the area, what should I do?

Some territorial aggression exceeds what is considered by most to be acceptable. These cat bullies are often described as ‘despotic’ as they appear to actively seek out territory defended by others to claim it as their own. They will enter houses, located over a wide area, attack the resident cats (and the owners sometimes if they get in the way) and spray mark vertical surfaces with urine before departing. The victims rarely fight back as a ‘despot’ will choose them wisely and often pick relentlessly on the old, infirm or timid cats in the neighbourhood. In the UK some pedigree cats, such as the Burmese and more recently the Bengal, represent a surprisingly large percentage of the reported perpetrators. Entire tom cats (‘despots’ are usually male) are also likely to behave in a similar way as will any domestic non-pedigree that is particularly territorial.

This can be extremely distressing, particularly as attacks occur within the cat’s own home, and there is always the temptation to demand that steps be taken by the owner of the bully, as that person is solely responsible for preventing future attacks. It is entirely appropriate that these measures are put in place, but the unpopular truth is that the victim’s owner must also take reasonable steps to protect his or her property. The victim cat is  clearly unable to deter intruders or defend its own territory so the owner have to intervene in this case.

There is some debate about whether or not these bullying cats are behaving abnormally for the species but, regrettably, there is little evidence to suggest that their behaviour is anything but normal for the cat as a territorial species. Domestic non-pedigree cats  or ‘moggies’ have been selectively bred over many thousands of generations to moderate their territoriality in order to live in built-up areas in close proximity to other cats. Expression of territorial behaviour is all a matter of degree and cat owners all over the world should be grateful that this is not a more common occurrence.

It is important, first of all, to establish whether the problem-causing cat is owned and that it is neutered. If there is no evidence of an owner it may be possible to request assistance for humane trapping, neutering and re-homing.

If an owner can be located then it might be helpful to mutually agree that the despotic cat should be confined indoors at night, if the fighting and property invasion occurs during the hours of darkness. The owner can feed the cat a late night treat to give some incentive to come in by a certain time. If the attacks occur during the day then the curfew hours should reflect that. If your cat is not the only victim then all neighbours with cats that have been attacked should be informed that the aggressor is confined at specific times so that they know when their own cats are safe. It would be useful for the despotic cat to have a couple of bells attached to its collar so neighbours and their cats can hear it coming and take any necessary action if the curfew is broken.

Your cat may find it reassuring if you block up your cat flap by locking it and placing a solid board over both aspects or close any doors or windows through which the aggressive cat entered the house. The aggressor’s route into the garden should be established and blocked where possible. Your cat can then be escorted into the garden if it shows interest in going out but an indoor litter tray should also be provided. If your cat wants free access outdoors in the future an exclusive entry system cat flap should be installed. Unfortunately no device will exclude the most determined cats from invading.

The aggressive cat’s home should be adapted to ensure it is provided with appropriate stimulation and resources as enforced confinement could be stressful. Sufficient warm beds should be located around the house to give the cat every opportunity to sleep to fill the void of activity. Active play sessions should be introduced to use up energy, particularly early morning and evening or at other times when it is normally most active.

Some despotic cats are very determined to behave in this way and often the only way to resolve the heated disputes that arise between neighbours is to re-home them to areas with low cat populations.

My cat’s been in a fight, what should I do?

If you are aware that your cat has just been fighting it is best to confine it indoors but not to give too much attention to start with - cats can be very aroused when they have just been fighting and they are best left alone until they calm down.  Superficial cuts and scratches are common and easily seen, but bite wounds are often difficult to detect as a cat’s teeth puncture the skin causing deep but narrow holes that quickly heal over, trapping bacteria inside. If your cat hides, appears listless or withdrawn or lame after a fight then you should consult your vet as it may have a bite abscess.

Am I liable for veterinary bills if my cat attacks someone else’s cat?

While inter-cat disputes are accepted by most owners as inevitable, on rare occasions the consequences can become serious – particularly in those cases where frequent injuries are inflicted by one particularly assertive individual. These disputes between neighbours can escalate and lead to threatening behaviour and even, in extreme cases, police involvement. The legal responsibility will vary from country to country and, in the UK, for example there are very few cases, if any, that have gone to court regarding a claim for damages as a consequence of a cat fight. 

Advice section: