Older cat not dealing well with new kitten

Our cat Panko, who is 7.5 years old, is really not faring well since we have brought a new kitten, Cali, in to the house. Panko has been the only cat in the house since she was about 1.5, when our other cat passed away. We have previously tried bringing another cat in to the household, but he managed to open the door that was separating them after a couple of days while we weren't home, and ended up attacking Panko. We have not tried again since then, which was about 4 years ago. Since then she has been desexed, and has really mellowed out. She used to try and attack any other cat she would see through the window, but recently has been more curious than aggressive, even sniffing and head-butting a neighbours cat through a screen door.
Three weeks ago we adopted a new kitten who was 8 weeks old. We have been following the traditional advice (keeping them separated, scent swapping etc). Tried moving their food bowls to opposite sides of the same door, but Panko wouldn't go near the door, even after leaving it there for 6 hours. We tried moving Cali to a different room and introducing Panko to the room where she had been previously, but she just sat in one spot not moving, growling at every little noise.
We have tried having both cats together in the same room under careful supervision for 15 minutes or so, but Panko will again only sit in one place, growling and hissing at Cali. As soon as Cali is back in her room, Panko is fine, even walking up the hallway and sniffing the door where Cali is.

I am really at a loss as to whether to keep trying to introduce them. Panko seems more afraid of Cali, and I don't know what else to do to help her to at least tolerate her presence. At the moment she won't move from a single spot when she knows that Cali is around. The past few days it feels like we are going backwards, with Panko lashing out and scratching me the last time Cali was out. We have purchased a pheromone diffuser, but have not noticed any changes from that so far.

Has anyone else been in a similar situation?

submitted by /u/-rad-ish
[link] [comments]

from Pets https://www.reddit.com/r/Pets/comments/g3j6eb/older_cat_not_dealing_well_with_new_kitten/