Multiple Cats in House

The number of cats in the U.K. is currently on the increase and so is the number of cats per household. Cats had previously been thought to be solitary animals but, more recently, it has become accepted that some cats can live happily with others. Whether cats will share a household depends on the temperament of the cat, its previous experience with other cats, the household and surrounding environment and the number of resources available to the cats.


How should I introduce a new cat?

The best way to introduce new cats to each other is slowly! Cats primarily recognise each other through scent and those residing in the same group share a communal scent. Therefore to help your current cat(s) accept your new cat as part of their group, it is important to build up a communal scent comprising of all cats. Keep the cats physically separated and swap bedding between old and new cats so that they start to become familiar with each other’s scents. The same can be done with food bowls.

The next step is to let the cats see each other without physical contact (e.g. through a glass door). The cats should be rewarded (through praise and food) for calm behaviour in the presence of the other cat(s). If at any stage, one of the cats is showing aggressive or fearful behaviour, go back a step.

If all cats are showing calm behaviour when seeing each other, cats can be allowed in the same room, again rewarding for calm behaviour. The first meeting often predicts the relationship the cats will have in the long term so it is vitally important to build up these steps slowly.

How many litter boxes are needed in a multi-cat household and where should I put them?

Cats often do not like to share their litter box with another cat and may not use a dirty box (whether dirtied by themselves or another cat). As a general recommendation, a household should have litter boxes equal to the number of cats residing in the home plus one. For example, if a house has two cats, three litter boxes should be provided.

Litter trays should be placed in different locations (never in a row all together). Since eliminating is a vulnerable position for a cat boxes should be located in quiet areas where risk of being disturbed is low. However, if utilising a very quiet area, do not forget the litter box is there as they need to be cleaned regularly.

What if some of my cats have suddenly started not getting on?

The first step would be to identify those cats that appear not to be getting on. Keeping a diary of the conflict that occurs can help identify which individual(s) are involved. Keep conflicting cats physically separated to ensure no further conflict can occur. Then you need to talk to your vet. It is possible for one cat to be acting aggressively to the other cats due to pain or discomfort. If the aggression is not medically related, your vet should be able to refer you to a behaviourist who can help.

Is there an optimum number of cats that can live happily together?

There is no perfect number of cats that can happily live together. Some cats will only ever happily live alone whereas others may be happy sharing their home with several other cats. A number of factors influence this including:

  • the number of resources within the home (litter trays, resting places, feeding and drinking areas)

  • the size of the home as well as the quality of the space within the home (e.g. open plan homes have fewer places where cats can find their own space out of sight of others)

  • the socialisation of the cat to other cats (has the cat had positive experiences of other cats in the past)

Is it better to have same sex or mixed sex groups?

In free-ranging cats, groups tend to be made up of related females (mothers, daughters, sisters, aunties etc) and their young offspring (male and female). Adult males exist only on the periphery of such groups. Thus, it is often advocated that multi-cat households should comprise females (preferably related) and one male. However, research has found that gender appears to have no influence on aggression between cats in a household.

What type of cat is best to introduce to the cats I already have?

If you already have more than one cat and they are living happily within the home, you must consider what advantages, if any, another cat would bring. There is always a risk that a new cat could upset the harmony. If you are certain that it is a good idea to introduce another cat, a kitten is often easier to introduce to adult cats than another adult cat.

I am out at work all day and thinking of getting a cat. Should I have two cats rather than one?

If you are considering kittens, then getting two should not pose a problem as they are likely to provide companionship and play opportunities for each other. Two kittens from the same litter is often advocated but if two from the same litter are not available, two from different litters should be properly socialised and introduced appropriately.

However, if you are considering adult cats, make sure they are cats that already reside happily together. Rescue shelters often have adult pairs available for re-homing that have a history of living amicably together. It is not advisable to choose two unknown adult cats since the likelihood of the cats not getting along is much higher than if they have positive previous experience of each other.

Are there any particular breeds that get along best?

No breeds seem particularly likely to be sociable. Realistically, there is as much variation in behaviour within a breed as there is across breeds. More important is appropriate socialisation to other cats during their sensitive periods (as young kittens), appropriate introductions and a household with adequate space.

Is it a good idea to feed cats together?

Unfortunately, no. While kittens may happily eat from the same location and even the same bowl, it is not advisable to continue this practice into adulthood. If a cat feels threatened while eating or feels that it has to compete for food, conflict can occur.

The best way to manage feeding in a multi cat household is to have many feeding sites in separate locations (i.e. separate rooms if possible). The same is also true for resting places and water bowls. Make sure there is at least one of each of these resources per cat.

I have a new cat and now one of my existing cats is urinating in the house. Why is this and how do I stop it?

Cats can urinate outside their litter boxes for a variety of reasons. The first step is to identify who is eliminating outside of the litter box and whether the cat (or cats) is urinating (most commonly a pool of urine on a horizontal surface) or spraying (most commonly found on vertical surfaces at base of tail height, may drip down onto horizontal surfaces).

The culprit(s) should then be taken to the vet for a medical examination to rule out a medical cause. If no medical cause is found, ask the vet if they can refer you to a behaviour specialist. The spraying or urinating may be related to the new cat in a number of ways, for example:

  • fear of the new cat

  • insecurity caused by the new cat

  • too few litter boxes

Alternatively the problem may be unrelated to the new cat, caused by a different trigger and the timing simply a coincidence. A behaviour specialist will help identify the cause of the problem and work with you to build a programme to help alleviate it.

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