Cats are slow to accept any changes, and you must be patient and not expect them to accept the new arrival immediately.
They are incredibly territorial by nature and will not take too kindly to another encroaching on their territory.
It may only take a few weeks to introduce a kitten to another young cat, and it can be a much easier experience.
The character of the animal has an enormous bearing on how long it would take for the new cat to be accepted, and you should never forget to give the resident pet a lot of attention too and not make them feel left out.
The current pet will be feeling highly insecure and will need plenty of reassurance.
When first introducing the cat it is essential that they are placed in a quiet room and not allowed access to the rest of the house.
Probably the best environment would be a smaller room in your house that you can be positive will be a place where they are not disturbed in any way.
It is crucial that the pet is not allowed into this room with the new arrival until they have had sufficient time to settle down.
All the essentials that your new cat needs should be in easy reach in the room with provisions such as food, water, the right size bed and litter tray which should be placed as far from the food bowl as possible.
The resident pet will go through the process of posturing and threatening the new arrival to let it know who is the boss.
This is a perfectly natural reaction and should never at any time be seen as unacceptable behaviour that deserves any punishment or reprimand.
Your pet will start to calm down as they get used to the scent and idea of a new arrival and should be given much praise and affection for showing such tolerance.
As the aggression in the residing pet disappears this is a sign of when to introduce them properly to the new cat.
The scent of the new pet plays a huge part in this, and a terrific way to do this is by using the same food bowl to eat out of, although not at the same time.
This is an excellent way of getting them used to the new cats scent.
They can be encourage to eat side by side by gradually placing the feeding bowls closer together.
This will of course only be done initially with the residing pet outside of the door of the new cat's safe room.
You can then begin to feed them at the same time.
They will soon become accustomed to each other and will feel less insecure.
Only after this stage can they be introduces to each other properly.
This will not be a quick and easy process and will require much patience and perseverance.
You present pet will be feeling particularly frightened too, and this must always be remembered.
Try to remain calm and give them attention as much as you can in equal amounts always remembering not to leave the resident pet feeling left out.
Keep between them at all times when they are first introduced and do not leave them alone together as this has the potential to be a dangerous situation.
The process of introducing a new cat, and the amount of perseverance, understanding and patience cannot be underestimated.
Your time spent following this advice will be rewarded, with your new cat feeling as if they had always been a part of your family.