Redirected Aggression towards Outside Cat

[Annieca2016]

I have two kitties, Snap (11F) and Pompom (9F) and live in a townhome. Well one of my neighbors (I assume) has been letting their cat wander free at night and so angers the crud out of Pompom. She'll hiss and growl and get all puffy at the sliding glass door because there's another cat she sees. Of course it's at 2 am and there's no way I'm chasing that neighborhood cat down.

I guess this has happened a couple of nights in a row because then this night, after they were fine all evening, something spooked Pompom and she attacked Snap. I broke it up by clapping (not my finest moment) but Pompom continued to be hissy and growling. Eventually she calmed down a bit enough to give them treats in separate areas of the living room but after Pompom finished her treats she went to see if Snap had any and they started hissing and growling again.

I know this is redirected aggression and I might need to do a reintroduction (which woof, not looking forward to after them having had rule of the whole house for 7 years). But I worry until the neighborhood cat is gone, it's a neverending cycle. I've considered trying to trap the outdoor kitty to walk to the neighbors and see who it belongs to. I've asked the HOA to remind people it's illegal to let a cat roam but they're no help. I've also considered maybe Pompom can only be upstairs at night where she can't see the other cat, but that feels like I'm punishing Snap too. I can't figure out a good solution.

 

[Kris107]

What about blinds or blocking the windows? There are cheap/temporary options. Also peel/re-stick windows films.

 

[FeebysOwner]

Hi. Until you can work on finding out more about this roaming cat and how to deter it, the answer is truly about keeping both of them away from that area overnight. You could build something, or even use cardboard, to block viewing access from at least the lower part of the sliding glass doors at night, but only if they can't find a way to look over the blockade. Any chance of setting up a spot upstairs that you could interest them in at night in the meantime? Keeping your cats from being upset and disrupted should not be viewed by you as punishing them. Going through the repeated disturbances of this nature is.

Not sure of the area this cat is roaming through or how close/far away it is from your doors, but sometimes laying chicken wire on the ground will stop them as they don't like to walk on it. It doesn't hurt them, it just isn't comfortable for them. You could also look into motion activated ultrasonic devices. They are inaudible to humans, and the sound waves don’t penetrate solid objects, so you wouldn't have to worry about disturbing your cats as long as the doors are closed. As far as I recall, they can be removed during the day, if you don't need them then, and then put back down at night.

 

[Mamanyt1953]

Motion activated, silent air cans can also work to keep an outdoor cat away from the sliders. It delivers a strong burst of air to the face, unpleasant but not harmful. It usually only takes a few days for them to take their business elsewhere.

 

[Annieca2016]

An update: I tried to trap the kitty so I could return it to potential neighbor or to a shelter. The trap I used was a little janky so they busted out. They haven't been back since.
Pompom has mostly returned to normal. I do think she's gotten sick because she's lost weight and is lethargic. I have an afternoon appointment for her tomorrow to get that checked out. She's not hissing or attacking her sister so that's good.
But... now Snap is doing the hissing and growling. I separate them when I can, but haven't been able to do it 24/7 until I get a new baby gate and get it installed later this week. What I find interesting is Snap and Pompom tolerate each other until it gets dark. That's when SnapCat starts hissing and growling at Pompom. Is there such a thing in sundowning for cats?

 

[Alldara]

Well. When ita dark that's when that strange cat would come along and make them nervous. So now they are anticipating it and getting nervous.

A slight change of routine in the evening might help.

 

[Mamanyt1953]

Well. When ita dark that's when that strange cat would come along and make them nervous. So now they are anticipating it and getting nervous.

A slight change of routine in the evening might help.

This is exactly what I was going to say!

 

[Annieca2016]

Well. When ita dark that's when that strange cat would come along and make them nervous. So now they are anticipating it and getting nervous.

A slight change of routine in the evening might help.

Oh, I am taking this as an excuse to spoil them with treats when it gets dark out!

 

[Mamanyt1953]

LOL, so we're moving from "redirection aggression" to "redirected satisfaction!" I approve!

 

[Annieca2016]

So another update: neighborhood cat has not come by in several weeks, so that's a yay! But in a "boo," Snap has started hissing at Pompom at any time of the day. Usually Pompom is minding her own business, walking past or eating, and Snap will hiss. Snap has lately been going underneath my bookshelf to hide which Pompom then follows her as a "What are you doing sister?" which makes Snap growl.
Tried gabapentin and Feliaway with Snap but neither seemed to stop the hissing. Both are doing everything else normally - eating, using the box, drinking, etc. I called the vet to get ideas but haven't heard back. I'm thinking I might have to do separation and reintroductions so I bought a baby gate to install this weekend. Snap doesn't show signs of anxiety most of the time. Like right now she's maybe 6 feet from Pompom who is snoozing in the tower while Snap watches out the back sliding door. From what I can tell, the trigger for Snap is Pompom getting close, but I can't determine what distance that is, or when it's going to be an issue.

Because it's not all the time, I'm not sure how to do the reintroduction. They both know the house and me. They know each other but for whatever reason in her walnut brain, after 7+ years of living with her sister, Snap has decided her sister is foe. I was hoping it would work itself out (naive, I know), but since it's happening more often and not tied to darkness, that's why I'm thinking of doing a reintroduction. Anyone have a good timeline for this?