Brother/sister cats no longer getting along

[Isithalftermyet]

I just wondered if anyone else has experienced this? Brother and sister from the same litter - both spayed/neutered. Now 11 - after living together harmoniously since we got them they now seem to hate each other. Lots of fighting with the male cat pinning the girl cat down - she gets so scared she will pee herself. Also there has been a lot of pooing and peeing in the house by one or the other so I now have to keep them in a back room. They still have access to the garden via the cat flap. No obvious issues that the vet could find. Have tried the plug in things to calm them and they seem to help perhaps a little...

Male cat seems to be behaving a bit weirdly all round so I'm wondering if he has a bit of dementia. He has poo-ed in his food bowl for example.

Any thoughts as to what we can do? Would be gutted to have to rehome one, and then it might not stop the toileting problem anyway in the remaining cat. The bottom line is that they are warm, safe and well fed but we have to keep them separate from the house and they hate each other. Obvs we do go in and make a fuss of them but it isn't the same as them having full run of the house.

Is there a particular area where the fights happen? I’m surprised the vets didn’t find anything amiss in a cat who poos in his fooddish, that’s highly unusual behaviour in any animal.

No particular area for fighting. It's proper nasty stuff with fur flying.

The poo-ing feels more like a behaviour problem to me, like a protest - it tends to happen if we are away for example or if there are visitors in the house, any interruption to their normal routine. And this is with them kept safely out the way in the back room...

Its probably six months since I last took them in so I could try again, but they are eating well and aside from being old(ish) don't seem to have any other health problems, no weight lost etc, not drinking excessively.

If one of them was ill but hiding it, would that account for the change in behaviour of the other? If one of them has the beginnings of dementia for example?

There’s a new feliway diffuser out, I’d have a look at the range and see which one would apply to them. It’s not cheap but neither are vet bills.

I have an older cat 15 years old now who is wanting more time away from the other 3 cats , she is getting forgetful and wants a quiet life . The other cats are 7,7 and 10. The vet did tell me that cats get a kind of dementia and to not move any of her stuff from the places our cat knows ,has this can cause distress .

Fluffycloudland77 - thank you for the tip on the diffusers. we were just using the classic one so I'll try the friends one!

pippapoo62 - good tip re not moving things around!