intro issues with new kitten and hissing

We got a new kitten last week and now our resident cat of 10 years hisses and swats at him whenever he gets within five feet. I’ve been keeping them separated but I’m worried about how to bring them together.

I know I should have done this better, but the kitten just appeared in our garage and we couldn't leave him out. I’ve written up the full history and the vet visit details in a separate thread so I don't have to repeat it all here: bandit hissing log and vet notes.

Right now Bandit is a 4-year-old dsh who is usually pretty chill, but he is bitey when he feels cornered. The kitten is about 10 weeks. I want to know if I should keep separating them or if I am overreacting to the hissing.

Hi Denise, first off, take a breath. It is very common for resident cats to be grumpy about newcomers, even if they have been in the house for years. Shadow is 10 and blind, and he still gets grumpy when Star, who is only 3, gets too energetic. You can see some of our struggles in this thread about Star's energy levels: star won't stop zooming.

The hissing is actually a good sign because it means he is communicating his boundaries rather than just attacking. I would not rush the face-to-face meeting yet. Have you tried the scent swapping method described here? how to swap scents properly

Oh no, I am so sorry to hear that. My cat Chloe is a 3-year-old dsh and she is super shy. When my baby is coming next month I am terrified of how she will handle the change. I read about my own struggles here: chloe is hiding from everyone.

If Chloe, who is already an adult, has such a hard time with just a baby crying, I can imagine how much harder it is with a kitten. Are you feeding them on opposite sides of the door? I read that helps make the other cat seem nice. See this thread for details: eating on opposite sides of the door

You are doing a good job by keeping them separated :)

My Mittens is a 12-year-old calico with arthritis, so any sudden movement or new cat makes her very stressed. I had to make sure she had a high, soft place to retreat to when I brought Pepper home. You can see my setup here: mittens needs a soft spot.

Since Bandit is only 4, he is still young, but the kitten is very active. Maybe try to keep the kitten in a small room first so the space is not overwhelming for Bandit. I hope it works out for you both.

Thanks for the reassurance, everyone. I did read the scent swapping thread and I am doing that twice a day. The eating thing sounds promising, but I am worried the kitten will just knock over his food bowl.

I think I will try the small room idea Donna suggested. I have a spare bathroom with a litter box and a high shelf. Does anyone have advice on how long to keep them in the small room before opening the door? I don't want to make a mistake and set back the progress.

I would say keep the kitten in the small room until Bandit stops hissing at the door for a full 24 hours. It might take a few days, it might take a week. There is no rush. The goal is for Bandit to associate the smell of the kitten with calmness, not fear.

Also, make sure the kitten has plenty of toys in that room so he doesn't get bored and start banging on the door, which will just startle Bandit. Good luck!