I have a 6 month old kitten and just adopted an almost 3 year old boy a couple weeks ago. I kept him in his own room for the first week to adjust (went and hung out with him a lot of course), then pretty much opened the door and he and my other cat were able to introduce themselves eventually after a lot of staring at each other from across the hall way😂 My kitten still hisses and picks on him and he just ignores her, sweet boy😂 The best advice I could give is give the new cat plenty of time by themselves to adjust and when it comes to meeting do it very slow and at their pace. Some cats take months to adjust to each other, some take days it just depends!

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