Hopefully a larger litter box will solve the problem. Meanwhile, again, make sure you clean with an enzyme cleaner like Home | Nature's Miracle
Yes that’s the next step. Though with one of those screens I can put over the door. I think I rushed it before, so am now taking my time. I want to get to the point there is no more hissing and growling before going to the screen. In the meantime have been letting them get line of sight by holding kitten in the presence of resident cat. Seems to be working as Lola now comes up to me and takes the treat writhing just a foot of the kitten. This week if continues to go well will put up the screen. Anyhow that’s why I want to interpret if Lola is ready for that.Honestly, not sure. But it doesn't look aggressive.
Have you considered trying the stacked baby gates at that door. Then Lola and the kitten can get near each other, even do pawsies, but still both be safe.
Here's a pic, from the How To Successfully Introduce Cats: The Ultimate Guide - TheCatSite article.
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Thank you. We did consider getting another kitten but have read that even that could have issues as there is no guarantee the kittens will get along either. We don’t have room for further introductions hahaI had a very similar situation when I adopted a kitten. My senior was 13 and had lived with another cat but it had been about 3 years of being an only cat. This was probably 2.5 years ago, I had brought the new cat in and tried all the things you're doing maybe for 4 months, and then finally just let them all out in the open because I wasn't sure it would ever be perfect. I did get a second kitten about 2 months into it. This helped the first kitten have someone to play with.
2.5 years later, I can't say that the senior and kittens were ever friends. She tolerated them, but she still hissed and swiped at them when they got too close. She just passed away this week. The whole time, I had been putting the kittens in a separate room overnight and I think she appreciated the break from them, and they frankly started to love the bedtime routine. That might be something tk teg
Have you considered a second kitten? after having two kittens at the same time and seeing how much they play together and bond, I will always try to get two going forward.