Integrating Household Cats – A Detailed Guide

Cats October 21, 2015 Admin 0

The successful integration of cats is not always simple. Many owners make the mistake of putting cats together with little or no consideration and... Integrating Household Cats – A Detailed Guide

The successful integration of cats is not always simple. Many owners make the mistake of putting cats together with little or no consideration and planning. This can work if the cats are especially easy-going, but it can also result in a show of aggression and a stand-off that can never be overcome.

Friction among cats inside the home can be extremely difficult to manage, at worst resulting in the need to segregate animals. A slow integration giving consideration to all cats’ needs will ensure no fur flies.

1. Factors Affecting New Cat Acceptance

Four key factors affect the propensity of existing household cats to accept new feline additions:

1. Temperament of Existing Cat

Consider the temperament of existing cats in the home and whether it is fair to introduce a new feline family member, or is the existing cat happier on its own? The temperament of cats and propensity to accept or reject a newcomer can be affected by their breed.

Domestic shorthairs are usually fairly relaxed meeting new cats, but careful and slow integration is always recommended; where it does go wrong, domestic shorthairs seem to have long memories!

Persian cats are especially sensitive and prone to insecurity. Moving in a new cat, especially a non-Persian, can cause distress behaviors in an established Persian. If you have a Persian cat already, give careful consideration to whether you should add another Persian, rather than taking a chance on a different breed.

Orientals like Siamese and Burmese can be possessive and territorial, in some cases ‘guarding’ their owner against feline or human newcomers. Introductions can be challenging.

Birmans, Maine Coons and Norwegian Forest Cats are usually affectionate towards new cats; their natural breed confidence usually means they don’t feel so intimidated when they meet unfamiliar animals.

2. Age of Existing Cat

The older a cat is at the time of change, the harder a new introduction will often be. It can be inappropriate to introduce a new cat to one in his final years; the stress on an older cat can be considerable.

The exception here is if the existing cat has always shared his space with another cat; in this case it is likely that he will not really relish being an ‘only cat’ and may appreciate a new companion, but in this case the cats’ temperaments, ages and activity levels should always be closely matched as far as possible.

3. Stress in Existing Cat

Cats with a history of exhibiting nervous or stress-induced behavior will usually find a new cat threatening. If there’s resultant friction then segregation of the cats will make matters even worse, since it renders certain areas of the home ‘out of bounds’ for the existing cat.

Signs of living with a generally stressed or anxiety-prone cat:

The cat has repeated cystitis, urinates around the home by squatting in corners or on furniture, or indulges in territorial spray-marking.

Cat shows needy and clingy behavior, asking for your total attention and affection whenever you’re around.

Cat shows tendency to over-groom.

Cat claws at the door or carpets if left in a room away from owner.

Cat generally doesn’t cope with trips to the veterinarian, and vomits or urinate in the carry-box en-route.

Cat stops eating or has less appetite when there are changes at home.

Cat hides from visitors.

Cat is frightened by sudden noises or movements.

Cats fitting these descriptions are often happier living as ‘only cats.’

5. Late-Neutered Cats

Where male cats have been castrated at an age past sexual maturity, they may remain unusually aggressive towards new cats. This is quite natural; prior to castration their hormones dictated a need for territorial defense, and force of habit once they’re castrated can mean that aggressive behaviors continue.

Male cats that are late-neutered and have actually been allowed to breed will often show even greater aggression and can attack other cats without warning. Many such cats remain suspicious and highly-strung around any other feline, especially another male. In this case it is preferable to introduce a female, ideally one that is still young and playful so that she isn’t seen as a threat.

Where the existing cat in the household is female and was neutered late, this does not make any difference; only males are affected by the late-neutering issue.

2. Integrating Bereaved Cats

If you have recently lost a cat through bereavement, your remaining cat may seem restless and could lose its appetite. Bereaved and grieving cats tend to pace around a property, unable to settle and sometimes mewing.

Although decisions to adopt new cats should never be rushed, in the case of loss of a cat through bereavement it can help to replace the cat as soon as possible if there is grieving by the remaining feline; your cat may be distracted in a positive way by the addition of the newcomer.

When choosing a new cat, try and select one similar in size, stature and gender, to the cat that died. Recognition of familiar features by your existing cat will sometimes ease integration, even if your cat knows it is looking at a different animal.

3. Is A Kitten or an Adult Cat Preferable?

Many people feel kittens will be less threatening and less problematic than introducing an adult cat. While a kitten may certainly be less intimidating to your cat in the territorial sense, if your existing cat is significantly older than the newcomer he may be irritated by the antics of a kitten, resulting in disharmony and stand-off.

Several factors make it less than ideal to introduce kittens to much older cats.

These are the differences in levels of play and interactivity, dietary differences, and the risk of any diseases introduced by a new kitten to a cat in its later years, when immunity may be compromised. 

Interaction Differences of Kittens and Adult Cats

Differences in levels of playfulness and social interaction can be one reason why it’s difficult to introduce kittens to older, more sedentary cats.

Kittens often chase and attack the tails of older animals, stalking and jumping onto older cats, and generally seeing them as playthings. Mature cats get quite worn down and short tempered by this, just as any person would if pestered by a toddler when wanting to sleep or read a book in peace.

If you’re integrating a kitten with an older cat, ensure that the kitten is a calm animal and not one that will hound the mature cat to a point where he cannot relax.

Dietary Differences of Kittens and Adult Cats

Many cat owners make the mistake of feeding all cats the same diet, irrespective of the cats’ life-stages. This sets up all cats to have health issues, potentially.

A kitten needs to be fed on a protein-rich ‘growth’ diet specially formulated for kittens. As he ages he will progress onto an ‘adult’ or maintenance diet, and later still a ‘senior’ diet (age 7-8 upwards). Responding to changing dietary shifts is especially important in pedigree cats.

Kittens and ageing cats, therefore, are quite literally generations apart in their product needs.

A ‘growth’ diet, if accessed on a sustained basis by an older cat, can prove difficult to digest. It can also lead to obesity and result, at worst, in kidney failure which claims the lives of a high proportion of older cats, especially pedigree breeds. Undoubtedly, inappropriate feeding is a factor in many renal failure cases. Persian cats are particularly prone to kidney disease.

The only solution for cats on very different foods is to feed the cats separately, but in this case you have to be cautious to see that all cats still consume enough food to maintain healthy body weight. Cats used to a pattern of ‘grazing’ through the day may stop eating enough if the food is now only offered at regular times and then removed.

Many veterinarians and rescue shelters will advise against integrating kittens with any cat needing a senior or veterinary (prescription) diet.

It won’t be a problem if your kitten accesses the diet meant for a senior cat, but it will certainly matter if your senior cat or any cat requiring a prescription feed, keeps eating kitten food. 

Health Risks Introduced by Kittens

Make sure the kitten’s health is very good, to avoid introducing illness to an older cat. Again, cats over 8 years of age generally begin to be more susceptible to illnesses, but many pedigree cats of any age also have lower resistance to disease due to genetic programs and indoor lifestyles.


The most obvious step in avoiding health risks is to choose a kitten from a reputable breeder whose home is clean and tidy, and where you are invited to see all the kittens and adult cats on the premises.

Before taking kitten home, ensure it’s received both sets of vaccinations and you have been given a vet’s stamped vaccination card. Make sure your adult cat is also vaccinated, and check his records to ensure repeat vaccines aren’t overdue.

Look for a kitten that’s lively, with wide, clear eyes, no obvious signs of sickness, and a good weight. His litter-mates and other cats in the home should also look lively and bright.

Take the kitten straight to the vet for a health-check before you allow it into your home. Then, isolate kitten in its own room for a week to ensure no disease symptoms emerge. Don’t take a pedigree kitten younger than 15 weeks of age.

4. Integrating Kittens with Mature Cats

Your cat will be aware there’s a kitten in the house even if they cannot access each other. When kitten has a clean bill of health and has been isolated for a full week with no illnesses developing, you can slowly introduce it to the household.

Allow your existing cat to accompany you into kitten’s room, rather than letting kitten roam the house. This allows a nice, slow nose-to-nose meeting. If kitten runs around the house before the cats know each other, your adult cat will be in pursuit and this may cause a stand-off.

It’s quite natural for adult cats to hiss and back away from a kitten, yet to remain fascinated and to follow it around. What you are observing is most probably inquisitive, healthy behavior rather than hostility. The adult cat should never circle the kitten giving sideways glances, and shouldn’t howl (a prolonged wail), raise the fur on its neck or back or pursue the kitten in an aggressive manner. If any such behavior happens, lift kitten out of the way and remove your adult cat from the room since these are signs of aggression leading to possible attack. 

5. Integrating Adult Cats

Broadly speaking, the same rules apply for bringing adult cats into the home, as when bringing kittens in.

Check that the source of the new cat is a healthy environment, not overcrowded and without signs of sickness in all of the cats that come into contact with the one you’ve selected.

Ensure the new cat is vaccinated and has had a recent veterinary check. When you take it home, keep the cat isolated for at least one week before any introduction to your existing pets, just in case disease symptoms should show.

Once past this point, you can slowly introduce your adult cats to each other. A simple trial can be conducted when the house is quiet and calm, and there are no other people around.

Allow your existing cat to enter the room where your new cat has been living; try not to be anxious yourself as cats are extremely sensitive to their owners’ moods. The initial visit only needs to last a matter of minutes; it can be extended every day until the cats are comfortable being in the same room. At that point, they’re ready to share the house fully.

Tips to Aid Integration

Obtain a pheromone plug-in diffuser from your vet. Plug this into a socket in the new cat’s room. Other plug-ins can be dotted around the home at floor level where the cats walk. The diffuser contains a synthetic pheromone that is similar to the scent given off by friendly cats to each other during socialization. This is why cats rub their cheeks and heads on objects, people and other cats; they’re spreading their reassuring scent.

Rub dry flannels or handkerchiefs against the cheeks and heads of each cat/kitten then rub the scent of the other cat onto each animal’s face. Leave the flannels accessible so they can be sniffed by each animal.

Blankets and towels previously used as bedding by each cat can be swapped around, giving each cat access to the other’s scent before they meet each other. Make sure each cat also has fresh bedding as it will not actually sleep on the bedding used by an unfamiliar cat; you are offering this bedding solely for scent familiarization.

Introduction can go more smoothly if you involve something that can captivate the animals, such as a toy on string or elastic that both cats can watch and play with, rather than being solely focused on each other. Remember never to leave these items with cats unobserved, because of strangulation or choking risk.

The First Meeting

The following tips should help you introduce the cats and to interpret cats’ behavior during their first meeting:

Some hissing and growling when cats first meet, is normal.

Don’t focus too intently on what the cats are doing; take in something else to do, such as reading a book. Over-focusing on cats when they first meet can raise their anxiety levels.

Allow the cats to stand nose-to-nose without your interference, but just look out for hostility and be ready to intervene if this occurs.

Adult cats do a lot of ‘posturing’ such as aggressive circling and prolonged wailing before any physical attack. This gives you time and warning to remove the new cat out of the view of the established one.

Never raise your voice at cats even if they seem to be about to fight; chastising will not be understood, but adds further stress and will makes matters worse. Don’t clap your hands or make loud noises.

Remain the calming influence between both pets by staying quiet and composed even in the event of conflict between pets. The key to reassurance of both pets is your calm voice and behavior, and a swift, no-fuss removal of one animal if trouble occurs.

Take time to reassure adult cats when they have shown fear or aggression. Almost all aggressive behavior comes from fear and nervousness. Talk softly to your cats separately, stroke them as appropriate and make sure they feel reassured. Talking is often enough, as too much ‘hands on’ can make matters worse when a cat is under stress.

Don’t let one negative experience deter you from trying again. Repeat the exercise every day. If necessary put the new arrival into a pet cage, ensuring the mesh is fine enough for him not to be attacked through the bars, while they spend time together. Don’t cage your existing cat as he will feel more vulnerable and anxious.

6. Freedom to Roam

Once the cats are happy to be in the same room on a repeated basis, let the new cat explore the house very slowly, one room at a time, with you at its side. Your other cat may also be there, and if it follows the new cat or kitten that’s quite natural as long as there’s no hostile posturing or howling.

Allow cats to wander the house with you cautiously observing at a distance, but not interfering. Make sure there are no access areas where a kitten or young cat can go into and get lost. As long as there’s no hostility between cats, you can continue to allow the new pet more and more access to areas of the home and keep an eye on it. If this goes well for an hour or so, you can try just leaving the new cat or kitten out of its room.

Always be aware of where the newcomer is, and look for it every hour or so, but don’t become fixated. Cats need privacy. If a cat hides under a bed or behind furniture, let it do that.

Some cats settle straight away and just are overcome by curiosity, but others are cautious. However, don’t let a new cat stay in one place for too long if it’s clearly hiding and scared, without immediate access to food, water and litter. One or two hours’ hiding is fine but then, if accessible without fuss, lift the cat out of its hiding place and reassure it before placing it back in its room. You do not want an animal to hide away to the detriment of eating and drinking and you cannot force eating and drinking to happen simply by presenting the animal with food and water; it will feed only when it feels relaxed and free of threat.

7. Feeding, Watering and Litter

At first, even if the cats share the same diet you will need two of everything and to feed the new addition alone in a room, to be sure how much he is eating and drinking.

It’s best to have a few litter trays in various areas of the home on an ongoing basis. Relying on just one will often cause a problem with a less-confident cat or kitten messing in the house. It can take kittens time to acclimatize to using just one tray, and adult cats will prefer to have several food bowls and litter trays available so that they do not need to venture into unfamiliar areas to perform these vital functions.

8. Leaving Cats Alone Together

When you’re sure that the cats can mix without hostility, you may leave them alone together but make sure there are plenty of things for them to do when you are out.

Invest in tall cat trees or climbers, and make available playthings like empty cardboard boxes, treat balls, and catnip toys. Remember that toys with string or elastic shouldn’t be left with cats or kittens unobserved. Leave them initially only for a short time and gradually extend the period.

Whatever the personality, breed and life-stage of your cats, taking plenty of time over their introduction and integration will always help to ensure a harmonious and stress-free cat household, and you’ll be glad you put in the time and effort.