(kindly reproduced from Behaviour Problems in Small Animals by Jon Bowen&Sarah Heath)
Before introducing a new cat, it is important to prepare for their arrival.
This should include:
Providing your new cat with their own room containing a litter tray, food, water and a variety of resting and hiding places.
Installing a Feliway (available from your local branch) will increase the sense of familiarity and security in this location.
Allow your new cat to become fully confident in this new location and with all members of the family. This may take a few days, after which your cat should be eating, resting and approaching visitors to this environment normally.
The already resident cats should be provided with several extra feeding stations, places to drink and additional places to rest and hide. A Feliway diffuser is also useful to increase their sense of security.
Your new cat must then be introduced to your other cats in a series of gradual stages. Cats primarily recognise other members of their group by smell, which is why cats sometimes react oddly to their owners after they have been stroking or handling other cats.
Stage 1-Scent introduction
Prepare several disposable cloths, each labelled with a cat’s name.
Use each labelled cloth daily to collect odours from the face and flank of the cat with whose name it has been labelled. The cloths must not be mixed up and must be stored separately in plastic bags to prevent cross-contamination.
Whenever going to greet, feed or play with your new cat, it should be briefly presented with an opposing cat’s cloth to smell and investigate. The cloth should be wrapped round your hand. Initially this may trigger a degree of alarm (the cat may back away, hiss or freeze). At this stage it is important not to force contact as your cat may become aggressive.
If there are multiple cats in the household, then the resident cats should be presented with your new cat’s smell, and the new cat with odours from different cats in the group.
With repeated presentation of the cloths, your cat should ultimately ignore the odour or may react positively to it. When all cats are reacting in this way it is time to move onto stage 2.
Stage 2-Scent swapping
After harvesting the odour from your cats, the cloths should be put together in a bag so that odours mix.
This combined odour is then used in the same way as above.
Once there is a positive reaction to this combined odour then you can mark yourself with the mixed odour so that when the cats greet they are unintentionally self marking with this new odour. The cloth should be rubbed on objects that the cats regularly rub against, including your legs.
Odour swapping may then switch to using a single cloth, as long as each cat accepts being rubbed with the scent from others.
Once all cats are accepting this new odour and are actively rubbing against the clothed hand and other objects that have been marked with the cloth then it is time to move to Stage 3.
Stage 3 Allowing your new cat to explore
Your new cat should be allowed to explore and utilise the rest of the house while the other cats are excluded or shut in an inaccessible room. This allows your new cat to learn all of the hiding and escape places so that as the cats meet, your cat does not feel vulnerable.
Once your new cat is using the resources in the home confidently, then it is time to move on to the next stage.
Stage 4-Limited face to face introduction
Your cats need to begin to see each other but without any risk of carrying out an attack. This can be managed using a glass door or mesh screen. Some child gates are made from mesh that provides a partial barrier. Mesh barriers are best as they allow some diffusion of body odours that are involved in identification. If neither is possible, then a partly open door may be used (open wide enough for the cats to see each other but not get through).
The cats are given food on either side of the screen at normal feeding times, or are distracted with a game.
It is also useful to rub the door or screen with the odour from the cats so that there is maximum chance of scent recognition.
The cats are encouraged to play and feed progressively closer to the screen, as long as there is no aggression.
Once the cats are showing no aggressive or fearful behaviour, they can be allowed to meet face-to-face, after an initial meeting through the door or screen.
It is important to continue mixing odours between the cats and applying their ‘group odour’ to yourself and common marking places in the house until your cats have begun to rub against each other or groom each other. At this point, Feliway diffusers and other environmental changes may be taken away gradually.
The total time for the introduction process may vary from a couple of weeks to a couple of months, but there is no shortcut if harmony is to be achieved.
Click on the video below to watch Vicky Halls cat behaviourist advise on how best to introduce a kitten to an existing cat.