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Stop cats fighting: A guide to eliminating stress in a multi cat household

Cats fighting - Photo by ROMAN ODINTSOV

Why are cats fighting in some multi cat households and not in others? What can you do to stop the drama in your house? Dr. Jacky May answers these questions in this article. This information is also important in evaluating and reducing stress in multiple cats households where dealing with one or more cat not using the litter box. If you are dealing with litter box issues as well, be sure to read our Guide to Evaluating A Cat Not Using The Litter Box

A Note About Feline Communal Living

First understand that not every cat was meant to live communally. That is our most interesting  (and rather unrealistic) expectation for them. Not theirs. Some cats do love living in groups.  Some cats only tolerate it but are happy enough. Some cats hate it with a passion and will never adjust well. Some cats start out ok and devolve into misery in a multi cat household. Cats are individuals with fascinating depth to their personalities and there is no reason to assume that they will all enjoy random strangers in their house automatically. Cats that hate being around other cats but forced to will quite obviously result in cats fighting.

Cats do not typically choose to live in large groups made up of ‘random appearing’ strange cats. They tend to be solitary hunters that pair up to breed, and then part. The female will raise her litters, often alone, and the groups that form tend to be sibling groups, sometimes from different litters with their mother. Breeding toms tend to patrol by and hang out during breeding season only. In short, they know one another and were raised together so they stay together. And when the juveniles become grown adults ready to start breeding – very often they leave or are driven out and must go establish their own territory with their own resources.

Now certainly there can be exceptions because there always are, but exceptions are NOT the rule. We are talking about the most common situations. And urban feral colonies do not count because they are artificially supported by provided resources that do not require hunting, protection, and fighting to maintain.

The point is – even the family groups are used to occupying a huge open territory with a lot of space and a lot of entertainment. Occupied minds with plenty to do and plenty of room to get out of one another’s faces and spaces do not have to fight all that much. Crunch together in a one bedroom one bath apartment with distant relatives for longer than a month and tell me how long it takes everyone to start fighting and feeling stressed and ready to bolt. Too many cats in too little space results in cats fighting.

Cats are very long lived, and their tolerance levels and preferences certainly develop and change over time through the different stages of their life. A single house is already less territory than a single cat explores in one day on its own ‘in the wild outdoors’. Adding more and more cats will most definitely increase the stress on the resident cats, and the management work load of the humans involved. If you are not prepared to work at keeping the peace, and handling cat stress levels, then you are not realistically prepared to support more than 1-2 cats in your home.

One of the very best ways to prevent cats fighting is to cap the number of cats confined into a small indoor territory. Always bear that in mind. Also bear in mind that one of the very first signs of stressed agitated cats in a multi cat household is not always fighting, but may be inappropriate peeing or pooping outside the litter box. Cats fighting obviously may come before or after a cant using the litter box starts but they are commonly happen together for similar reasons in multi-cat households.

If you want to prevent cats fighting to begin with, then give very careful consideration to whether you have enough space to offer numerous cats, and enough time to devote to enriching their environment, handling their husbandry requirements (feeding, watering, cleaning many litter boxes) managing their different personalities. Preventing and planning to avoid cat fights is far easier than stopping a blood feud once it has begun.

Determining which cats are stress-ors and stress-ees

In any multiple cat household there are top cats that like to be king of the hill. But many times people to fail to realize that this can be a very dynamic position. Age, time, group dynamics changing, and social development stages can result in some cats becoming more or less confident, or in cats preferring different resources (food, water, litter, etc) with more or less vigor. One cat may be a food hound and so he bullies others off the food. Another cat may despise sharing litter boxes so he controls and bullies the litter box room. Different cats within the same house may seek and succeed in controlling different things. This complicates working out stress point triggers.

Because the King Cat may differ, you need to be expert at watching the super subtle versions of cat stress and agitation. Everyone recognizes when a brawl has actually broken out. That is easy. It is not however always so easy to recognizes the constantly stressful level of bullying in the background. Nor is it always easy to tell when a cat is aggravated or stressed prior to the explosive moment when cats fighting obviously break onto the scene. If you can intervene earlier that is always better in the long run. Plus identifying the correct dynamic can really help inform the best way to treat the problem of cats fighting or eliminating inappropriately in the house.

The control freak cats most commonly tend to be extremely subtle in how they exert access control over the preferred resources. For instance, the bully cat often appears to be benignly sitting at the hall entrance doing “nothing”. They are not in fact doing nothing. In the cat world they are standing there looking mean and cracking their little kitty knuckles while they block access to their preferred resource. Simply sitting there and watching intently can be enough threat to a shy cat or just a cat not that committed to said resource from walking down the long narrow hall to get to the food/litter/water/best sunny window in the house.

The bully cat may look calm, there may be no obvious signs of cats fighting, but they are not just minding their ow business benignly. They are in fact blocking access to a needed or wanted resource by silently exert control over the other cats’ access to that resource by threat of attack. The rest of the cats have to decide if they reallllly want to go through the threat and the argument and the slap and hiss fest to get to the litter box or not. Maybe they decide that it is way easier to just go on the bathroom rug which no one is guarding instead.

When cats fighting really break out and the fur flies, often the cat that is accused of being the ‘obvious’ instigator is in fact the bullied cat.  Eventually sometimes the blocked cat gets fed up with the subtle bullying and they bow up and try to fight past. They did indeed rush the silent bully King cat and they get blamed for starting the fur flying fight. They were not actually the instigator but rather were the stressed out injured party that was pushed too far.

In a similar fashion, predatory cats can sneak around and prepare ambushes in common paths toward frequented resources. What better way to entertain yourself if you are a bored cat than figuring out that your favored prey sibling always tries to go the favored nap spot at 4 pm-ish. The predatory cat ambushes the prey and whammo you have cats fighting and may not have recognized who was stalking whom in the first place.

For help determining which cat is the stressor/bully cat and which cats are the stress-ees/victims take the time to look over our Feline Body Language Resource article. You can never have too much information and skills on hand to help you decipher problems and stress points in a multi cat household. Body language understanding is a key skill in preventing cats fighting and unraveling what and where the triggers occur.

Why are your Cats Fighting or Stressed?

Cats most commonly stress over resources above all things. Increasing stress results in decreasing tolerance which in turn results in cats fighting. Stress also can and does cause inappropriate elimination issues with cats (meaning they pee or poop outside their litter box).  Stress also commonly causes some cats a painful bladder inflammation that MUST be addressed medically as well as behaviorally to be successfully resolved. Pain increases stress and decreases tolerance too.  

So what are resources? Resources refer to the cats’ needs for happiness and health such as food, water, territory (the best sunny nap spot), preferred toys, preferred people, etc. Cats get stressed when they cannot freely access the resources that are important to them. In a communal living situation there are two ways resource stress tends to be caused – if one or more cats try to control the resource access, or if there are predatory play cats that spend their time stalking their brethren to pounce on them (usually on the way to resource pathways). 

So solitary hunters are very protective of their territory and the resources in it. Cats fighting to maintain control of resources is perfectly natural. But like many perfectly natural behaviors it is not desired in a house bound companion animal. Likewise cats’ play behavior imitates their ‘natural’ tendencies: stake out likely hunting areas (desired resource areas), stalk, hunt and identify easy prey, chase, and capture. Rinse and repeat over and over all day with some napping thrown in. Their natural behaviors tend to lead toward cats fighting, but they are not usually crammed together in one area so they usually manage to stay out of one another’s faces especially if the area is resource rich.

Cats fighting or inappropriate eliminating in a multi cat house persistently usually indicates one or more of the following common stressor points:

  • Resource limitation stress = not enough of a particular resource
  • Resource access stress = bully cat or predatory play cat blocking easy access
  • Lacking enrichment = the environment needs more enrichment or some of the individual cats do
  • Preferred isolationist – in the mix there may be a territorial little tiger or shy introverted soul
  • ‘Stranger Danger’ = An outdoor cat has come too close or a resident cat went to the vet and returned

That sums up the basics of the most common reasons why there are cats fighting or eliminating inappropriately in a multi cat household.

Immediate Triage for Serious or Repeat Episodes of Cats Fighting

The very first step for handling cats fighting is to separate and isolate as needed to put an IMMEDIATE end to repeated attacks. Do NOT allow cats to keep fighting. They have memories like elephants for serious bad blood episodes. The longer and more seriously and more often they actively try to hurt one another in a serious way, the harder and less likely it becomes that you will manage to get them to happily occupy the same space again. So STOP the fighting, and isolate.

We have a complete article about How to Isolate and Introduce cats. It is designed to help with first time new household introductions. However, the principles for success in isolating and re-introducing fighting household cats is the SAME. Read that over to get the help you need with those instructions and recommendations.

How do you help decrease the house stress for the cats fighting?

We will address how to evaluate each common stress point above and the usual way to approach treating the issues. The common reasons for owners to fail trying to solve the problem on their own is failure to implement a complete plan and/or failing to allow enough time for the changes to help decrease the stress level in the household.

Trying 4-5 different tiny pieces here or there as a tip or trick and do not really assess the WHOLE issue of stress stacking in a multi cat household. Then most owners tend to give those pieces all of 10 seconds to work before throwing up their hands and announcing they failed.

The cats did not get stressed to the point of consistent disaster overnight usually. An initial stressful reaction to one another is one type of stress, but daily stress for weeks and months is a whole different bad ball of wax. It takes time to decompress from daily high stress. So be as complete as you can AND give the adjustments time to help. Slowly add more adjustments based on what you see. Do not add one item and then snatch it away when whatever did not work in 120 seconds flat or because it was was too much trouble. Time is an essential element of success.

Evaluating Resource stress points in cats fighting or inappropriately eliminating in the house.

Resource limitation is easiest to correct. If there are not enough of the problem resources then add more. More food stations, water stations, litter boxes, hiding spots, elevated watch spots, window nap places, cat condos, etc etc. But remember the second issues is resource access!

These two things together (limitation and access) means that you need to carefully study the layout of your home and the resources in it. Make certain that there is ALWAYS more than one of <whatever resource> available in more than one area of the house.

For instance:  having 8 litter boxes for 4 cats is a fabulous, great quantity of resources. But if all those litter boxes are right together in one room at the end of a long narrow hall then there may be a serious access problem.  The litter box King bully can sit ‘benignly’ at the hall entrance and successfully block access of all eight boxes at the other end of the hall (or up or down the stairs, etc).  The other cats may opt to just go without or pee someplace else and avoid ‘running the stress gauntlet’ entirely.

Do all the cats have different areas where they can get up high and away from one another? If not they should, if possible. And again not in all the same place. Think multiple amounts and easy access while looking at each type of preferred resource.

If you have a resource blocker (whether bully or predatory stalker) in the house then add duplicate resources in more than one EASILY accessible place. Make sure that one cat cannot effectively block all access routes to every food bowl, for example. Look at your house and think like a cat trying to be King of the <resource> and make it impossible for all of whatever <resource> to be body blocked at once by a single cat to avoid cats fighting and/or being stressed out.

You need to consider the general pathways throughout the house as well and not just directly to and from a resource station area. Even if there is zero resource blocking going on, sometimes you have a predatory cat whose preferred mental focus is to hunt his communal housemates. Sometimes they get way too carried away with that. This may be great fun for him but if excessive then you can be certain it is stressful for the prey cat, especially if they are shy.

Freedom to move about un-assaulted is a high value resource in my book that is related to access problems. If a cat cannot move from room to room without being assaulted then you will end up with stressed out cats fighting or peeing everywhere. Often that sort of stress can be alleviated by looking at each room like a cat that is stalking prey and look for clear bottlenecks. Bottle necks in moving freely around the territory are BAD for communal harmony.

How can you help that? Can ‘elevated highways’ be added through a room – such as traversable shelving, or just thoughtful placement of couches and cat condos?  Can the ‘prey’ get out of each room in more than one way?  If the only way to get through a room is right through the middle of a wide open space then you have a bottleneck, especially if you have a very shy retiring sort of cat being victimized. See if you can work out how to make it possible for a cat to choose a different route if a predatory cat is stalking one of them.

It can be remarkable how much the stress level drops when you simply make sure everyone can choose more than one way to go through a room. An ambusher cannot cover to ways through at once, and you can bet the prey cats figure out super quickly how to watch and avoid IF they are able to choose a different way to go! Open up the ways for traffic to flow is grand way to reduce stress and decrease cats fighting or a cat not using the litter box in a multi cat household.

I had two cats that used to have issues. One was a predatory high prey drive nut. The other was a shy frightened soul. Moved to a house that had a larger living room area and I happened to position a couch such that she could go behind it to traverse the room or on top of it – and she never had to get out in the open middle and constantly attract his attention anymore. 

The predatory dude could not be in all places at once. She easily avoided him on her own after that. Consequently, I saw her out and about way more often, and sitting happily here and there in a room looking relaxed. Much less stressed out hiding going on from her.  He still amused himself trying to stalk, but she was instantly perfectly capable of foiling him and both were instantly more relaxed and happy overall. I was much much more conscious of traffic flow and providing different routes through each room after that.

How to provide ideal enrichment to stop fighting cats and a cat not using the litter box

Too many cats and not enough enrichment in their environment is major contributor to stress in a multi cat household. If all the cats are not adequately occupied with enough physical AND mental exercise in a day then problems will brew and cats will end up stressed. Stressed cats stop using their litter box and issues with cats fighting begin to snowball. Some cats begin to be aggressive towards humans in the house when they are overamped and under-engaged physically and mentally.

One of the easiest and least involved ways to assist most any cat problem is to make their world a more activity filled and mentally challenging place. If the environment is keeping them occupied and you are engaging their brains and not just their stomachs then they stop focusing on assaulting each other, and stalking and attacking everything and everybody that moves much more quickly.

We have an entire article devoted to heping you understand HOW to BEST enrich your cat and engage their awesome little brains. Just throwing a wad of toys out to be ignored is NOT engaging. Read further here: Feline Enrichment Principles: Keep your bored cat happy

Dealing With an Preferred Isolationist

So what if you go through all the issues presented and fix them up and find that you still have one cat that just cannot stand being around the other cats or you are still dealing with a cat not using the litter box? What then? At this point you really need to strongly consider engaging the services of a professional feline experienced behaviorist. Dealing with serious problem cats in a multiple cat environment that do not easily respond to common fixes usually requires very focused tailored assistance by an experienced person.

If you are committed to keeping any cats fighting or a cat not using the litter box that did not correct easily with these methods then engaging a professional behaviorist to help you is hands down the best bet. You can use search tools available at national veterinary behavior sites to search for one near you (or able to teleconference): DACVB or AVSAB at these links. Another useful link to search for certified behavior trainers is in numerous countries is IAABC. Or ask your local veterinarian if they have a recommendation.

Stop gap measures for cats fighting always include separate and isolate as mentioned above. How do you handle cats that are still problematic? Separation can be permanent if needed with a cat that cannot get along because they frequently bully or are picked on. Consider isolating those cats that would prefer to live alone or need to live alone. If you have a large enough area to keep them separate and happy then great deck it out with all their own resources and spend some quality alone time specifically with them playing and cuddling. You will likely find they are more happy away from the fray than stuck in it.

Medication. Check with your veterinarian if you are unable to engage a behaviorist. Talk to them about medications to try if you can reliably medicate the affected cats. It can make a difference and is always worth a try. They can often be weaned off if it helps and the cats are able to settle down and coexist peaceably.

Shy anxious cats often do well alone in smaller spaces. Bully cats can too, but if they are highly predatory they may get too stressed by not enough outlets for their mental and physical energy if their separation space is too small. You can increase their enrichment activities in their part of the house, or consider buying or building them a catio outside. Many times those cats do better with more and varied things to focus on that tend to be easier to find in a supervised safe enclosed jaunt outside. Don’t forget to check out the feline enrichment guide to help with more specific suggestions.

With the shy cats or bully preferred isolationists exhibiting stress by the cat not using the litter box, consider making them a ‘safe room’ of their own with their own resources that they can spend the night in at least.  There are microchip activated cat doors that will allow use by only certain chipped cats. Those can also be used on enclosed indoor cat condos or big boxes to provide some rest time for stressed cats if a stress rest room is not possible.  Several daily hours of rest from the stress of being stalked and harassed can go a great long way to solving constant stress contributing to fats fighting or a cat not using the litter box.

How to Deal with Cats Fighting because of ‘Stranger Danger’

This is one of the least common causes for cats fighting but it tends to be the most severe and sudden. If you have a cats that suddenly ‘out of nowhere’ seem to have lost their tiny minds and are severely attacking one another then this could be a factor.

In the case of any sudden severe aggression that does not seem to have any cause, you should always isolate the aggressor for safety of all as described above. Then arrange a veterinary visit to rule out any medical cause, seizure, neurologic problem or pain. In other words a very thorough work up. Never assume sudden intense episode of cats fighting with no apparent trigger is NOT medical. It often is. The visit will also allow you to get some medication to assist in calming the cats down at the same time. Usually needed so a win win!

Because it is very intense and can be long lasting in some cats we have an article devoted to it alone pending. If it is ruled behavioral then most commonly what launches this brand of cats fighting into being off is when a resident cat has gone to the vet and come back smelling wildly differently of many strange cats. The cats remaining at home do not immediately recognize them and get flooded with fear of a strange cat invading their safe home. They exhibit often extreme anxiety based aggression.

A similar severe ‘stranger danger’ basal reaction to an outside stray seen or scented too close to the safe house space. This can be serious sudden trigger for indoor cats fighting, especially cats that are extremely territorial. It is quite obvious this the trigger if you happen to see the initial reaction. However, if you were not present, then you will be stuck wondering what on earth happened to your previously happy cats all of a sudden to cause death match cats fighting and terror galore.

Sometimes this type of severe ‘stranger danger’ response takes a long time to calm down, and can trigger problems in cats getting along that will require you to put many of the above mentioned plans in place to help them settle back down and reset once they are calm and back in the same space. More soon on this subject.

Helpful Products to Reduce Feline Stress

It is always worth a mention of what types of over the counter products can help support stress reductions for cats fighting or having litter box use problems in a multi cat household. None of these will solve any issue on their own (sorry no magic one stop easy tricks here), but they do usually assist decently and noticeably when used as part a comprehensive effort. They should always be combined with the evaluations and efforts mentioned above for best effect.

Again do not expect miracles, but if you want the best chance to fix the issues associated with cats fighting a cat not using the litter box – then be as complete as you are able to be in implementing these secondary helpers along with the heavy lifters of the modification efforts above.

Over the Counter Products that can assist stress:

There are many that can assist decently in mild to moderately anxious animals. You need to have a realistic expectation of them though. They tend to assist your other efforts nicely, NOT magically make for a calm cat on their own. The more severe the anxiety, the less obvious the assistance of OTC supplements will be. Some things to consider are:

  1. Feliway or Comfort Zone Diffusers – good for a room
  2. Feliway or Comfort Zone Sprays – good for use at specific areas like by a separation barrier
  3. Purina Calming Care Probiotic – accepted readily by most cats sprinkled over their food.
  4. Vetriscience Composure treats for cats
  5. Zylkene for cats
  6. CBD – not particularly effective thus far in my experience with truly stressed cats.

In communal stress situations consider using pheromone diffusers (Feliway or Comfort Zone) in the resource and ‘accident’ areas. 




The spray versions can be useful additions in the ‘accident’ rooms also. 



There are also calming/stress diets for cats (Royal Canin, and Science Diet).

Royal Canin Calm

Science Diet Multicare Stress


Purina has a calming care probiotic. 

Purina Calming Care Supplement