Introducing a new kitten to current pets
I always get asked " We have a cat/dog at home, so you think they will get along?" I strongly believe that if you actually spend 14 days doing it the proper way, they will be sleeping together in no time.
Step 1: Once you pick up your new family member and bring them home. 14 day quarantine is a MUST! You can have the healthiest cat and the kitten you picked up can also be the healthiest kitten but they grew up in different homes and are used to completely different antibodies. Because cats can have stress induced health issues, meeting a new family member is very stressful so to avoid this huge stress on both ends, we need to ease them very slowly and at a very comfortable pace for them.
Step 2: New family member needs to be put in a small area such as a bedroom where her/his food, water and litter box will also be placed (temporarily). They might act intimidated and or scared, they might even hide under your bed. This behavior is absolutely 100% normal! Let's throw you in to a new home with complete strangers that keep saying these "cute" phrases OVER and OVER again with this annoying voice!! New smells and surroundings with nothing but a blanket that somewhat smells very similar but not so much? Exactly, I don't anticipate you feeling so hot yourself. Just be there and hang around. Be PATIENT! Let them get comfortable and they will come to you, I promise!
Step 3: The antibodies will automatically start transferring because you going in and out of the room will start the initial contact without the physical contact, make sense? They will sense that there is a new cat in the house and will sit by that door and wonder who the heck is in there? They will exchange a couple of meows and will stick their paws or even their tail under the door and share their scents. This, ladies and gents, is the 1st initial step in them becoming best buds
Step 4: 14 days has past! Woohoo you made it!! I mean YOU not your cats because majority of the time the quarantine is not fulfilled to the end because you as a furparent feel that they can't wait but a cat can't tell the difference in time so cheers to you for actually making it to day 14! By now your furkids are so anxious to put the "face to the smell" sorta thing that they will not have time to aggress against each other, which is what we were aiming for to begin with! 1/2 more day and they will finally meet! So day 14 we switch them. You take your new family member and allow them to roam the house while the other explores the room with closed door. Half a day is usually suffice. You can also put treats for them in the switched rooms so they associate this transition as a positive one.
Step 5 & Final: The moment we have been waiting for *drum roll please* introduction!
Open the door and sit on the floor near by and observe!! They will puff their tail out and might even make aggressive meowing sounds, please do NOT intervene because this is the critical moment where they determine who will be the dominant one. They can also paw at each other but if you pay close attention, their claws are not out because they're not strangers anymore. Always keep talking to them through the introduction with a calm voice. Your cat will be very intuitive with you and will react as " well my owner is calm and happy with this strange ball of fur with 4 legs, then I should be too!". Treats are also a great way to make them associate the kitten as a positive. If you have more than 1 cats that need introduction, I would strongly suggest to introduce them 1 by 1. Once you see that they are running around and happy, take the other one and do exactly the same thing as with the first.
I would strongly suggest to deworm all your animals including the new family member about 3-4 weeks after the introduction and maintaining it as a preventative routine every 4-6 months for 2 cats, 3-4 months for 3+ cats. But that's a whole other post.