Hello! Am new to this site and would like to ask for advice on our domesticated cats:

We moved house 3 months ago from apartment with terrace to small villa with walled garden. Our 2 cats (both previously adopted strays from 8 & 4 yrs ago) have adapted very well to new surroundings (kept inside for a while) and garden and up to yesterday both went outside during the day, sniffed around etc. Last night we got back home to find the older cat extremely stressed and aggressive towards the younger one - it's as if older one doesn't recognize her house companion anymore. Totally hissing and not accepting the other and very different weird behaviour. The younger one is more feral but we have lived with both accepting each other for the last 4 yrs together. Could it be to do with the fact that both have seen 'real' feral cats outside now as they sometimes come into our new garden and have picked up smells from them? As far as we know no feral cat has been inside our house since we moved in. But why the sudden inter-aggression? Older one also seems very lethargic and very hesitant - much more so than usual. Have booked vet's appointment for a check-up in case of anything serious. Any advice gratefully received, thanks!

It could be the outside cats. Do they have access to the garden all the time, or only when you are home? If they were inside and saw cats out in "their" territory, it's possible that one attacked the other. It's called displaced aggression... they want to attack the outside animal, but if an inside animal startles them at that point, they attack the inside cat instead. I read about one cat that did this after seeing its own reflection in the window.

Hello Froggy!

Thanks so much for a quick feedback, much appreciated. I hadn't heard of displaced aggression but having seen the vet this morning, he also said it was probably the stray feral cats outside. Maybe one of our cats had a stray scent on it from our garden and took it inside, whatever. But your feedback was very reassuring although now I have to try to get the cats to refamiliarize themselves with each other again. After living with and tolerating each other for the last 5 years! How weird is that?

I hope they get used to each other again. Incidentally I bought some feliway diffuser from the vet as he said it might help; it's basically a hormone from cats' inside cheek! Supposed to calm them down so we'll see. I have also washed one cat and will do the other to rid it of any lingering outdoor cat smell. But suppose that's only temporary - as soon as they go outside again, same will happen again?

I would look at the garfden to be sure there are no plants or stagnant pools of rainwater anywhere that they could have ate or drank that caused them some type of upset. Begonias for instance have been known to cause symptoms like this.

Many thanks WildandBlue - didn't think of that. We do collect rainwater/aircon water to water our plants and I know one of our cats drinks from there - but not the one showing symptons. I saw a stray cat again this morning in our garden and it's very difficult to stop other cats coming in unless we install an electric fence or something!

I do know that most cats don't like peppermint oil - at least ours don't and when I sprinkle it on sofas / areas I don't want scratched they definitely shrink back. Maybe I should do this around the garden walls but it'd probably evaporate after a day or two. Any other advice on 'safe' deterrents I could install against stray cats?

Just having water outside could attract them, as well as if you feed the kitties outdoors. They dislike the scent of lemon or thyme, there is a good groundcover herb called lemonbalm that grows rapidly and gives off a lemon scent when walked on. (My mother used to sprinkle ammonia along the fenceline to keep stray cats out of our trashbags on garbage day)

They are also supposed to dislike rue. And if you are willing to modify your fence, there are things like Pictures - The Affordable Cat Fence in action! that will keep your cats in and other cats out. Good luck!

Many thanks wildandblue - actually the cat fence was recommended to me someone else living the US but think it was an electric type, bit drastic!

Thanks for info about lemonbalm; good idea. Also peppermint e.g.. Aromatherapy oil is something cats don't seem to like and I sprinkled some along the wall the other night. Seems to work. I will try to plant peppermint plants maybe in hanging basket or along wall outside and see if this works. Will keep you all posted! Thanks so much again. Cats are now eating in same room but from different bowls obviously but the freaked-out one still hisses and won't have anything to do with the other. But seems to be less 'vicious' to the other than before. May be a long process towards reconciliation.

It might help if she feels she is not "trapped" out there, if you leave the porch door ajar or something and she can run in if she's frightened