A proper introduction allows a new cat to built secure relationships with his new family and any resident pets. Skipping an introduction by forcing the new cat to deal with an unfamiliar home and residents straight away can do more harm than good. Any new cat will be upset and confused with the new surroundings and resident cat(s) will be upset that some strange cat has been dumped in their territory.
It is essential that all new cats are up to date with vaccines and have tested clear for Feline Aids and Leukaemia before they are allowed to interact with other household cats. If the new cats background is unknown, they must be given a complete course of vaccines and blood tested for Feline Aids and Leukaemia to establish their current state of health.
Before the new cat is brought home, decide which room can be used as his own room for the next few weeks. Ideally this would be a spare room, though an occupied bedroom can be used at a pinch. Avoid using a bathroom, as they are uncomfortable and boring for a cat. In this room place an uncovered litter tray in one corner and as far away as possible place the water and feeding bowls. This is important, as cats won't eat if their food bowl is too near the litter tray. Build a simple cat bed by placing a blanket in a small cardboard box lying on its side and leave simple, quiet toys scattered on the floor. Like ping-pong balls or catnip mice do not forget to place a scratching post in this room. Try and cat proof the room by removing anything breakable or dangerous and blocking off any places where it would be inadvisable for the new cat to sleep.
Place the new cat in his room, straight away. Open the cat carrier then leave the room, turning off the light and shutting the door on the way out. Allow new cat a minimum of four hours to investigate the room. Do not be surprised after re-entering room to have lost the new cat, he is still there but successfully hiding. Sandy spend the first two days hiding in our sofa bed base, Bramble hid behind a box of books and Treacle's hiding place was NEVER located !!! Confirm existence of your new cat by monitoring the level of food/water bowls and checking for paw prints or deposits in the litter tray.
Be patient and the cat will come around but there are several suggestions that can help, when visiting the new cat's room, sit or lie on the floor and wait for the cat to come to you for attention. Reading a book out loud can help to calm a skittish cat or leaving a radio playing a classical music can have a similar affect. If possible take turns to sleep in the room with the new cat, this allows him to become accustomed to his new owners on his own terms. It is important that the new cat remains isolated in this room until he feels totally secure and relatively happy in this small space.
In the meantime the resident cats will have smelled that there is someone new in the house. Our cats usually ignore the spare room for a couple of days, hoping that the new cat will leave !!! Though your cats may remain glued to the door eager to meet the new cat. Start swapping toys and blankets, between the spare room and the rest of the house to swap smells around. By this stage our resident cats are usually playing paws with the new cat under the door. i.e. They take turns sticking their paws under the door and the new cat of the other side of the door smack the paw !!! Wait until until the new cat is comfortable enough to want to leave the spare room. This can vary a lot Treacle wanted out after 30 minutes, whereas our six year old Sandy stayed in there happily for four weeks. The average is about a week but it is important not to rush this stage, the new cat must feel confident enough to want to interact with the house and other residents.
If there is a choice of resident cats in the house pick an easy going friendly cat, who is less likely to threaten the new cat. Take this resident cat to the new cats room and let them interact under supervision. Feeding both cats together can help improve their relationship. Introduce all residents cats to the new cat in the same way, with short visits to the new cats room.
When the new cat actively tries to leave his room, leave the door ajar and let him start to explore the rest of the house and allow him to encounter other resident cats. Always be in the house watching/listening out for problems, when the new cat is exploring. Ensure the new cat is kept in his room at night or when the house will be empty.
There will be some hissing and fighting to establish the hierarchy, whilst the cats decide who is the top cat. Which has nothing to do with which cat was in the home first or what the owner thinks. Monitor the interactions carefully if you think either cat is being aggressive separate them straight away. Several short introduction sessions are better than one long one. Cats need to find their natural place in the household, the quicker they sort out relative levels with each other the sooner harmony will rein. Once all cats are relatively happy, they should be introduced to each other for an increasing length of time, until they are together during the day with supervision. When it is clear that all cats are interacting well, the new cat can be allowed to out of his room and be given free rein of the home.
The entire introduction procedure varies from a couple of hours (Treacle settled this quickly but this is very rare) or much longer (three months and counting for Sandy). An average introduction takes a month to complete but remember that some cats can take months to settle properly in a new home. Inter-cat relationships are very complex, some cats love each other and actively seek out another cat for mutual grooming sessions. Whilst other cats are life long enemies and use the house and garden on a time share basis, in order to avoid excessive fighting. If the relationship between the new cat and the existing cat(s) becomes intolerable, either the introduction can be repeated very slowly or the new cat may have to be rehomed. Some cats especially young kittens will frequently wrestle and play fight, this is not to be confused with serious fighting. If you are unsure which is which separate the cats and seek professional advice from your vets or pet behaviourist. Inter-cat relationship ebb and flow over time, with the cat's relationship changing from season to season. Often cats are more tolerant of interacting with other cats in the colder winter months, especially if this involves sharing a warm spot in front of a roaring fire.