Our cat (domestic short hair moggy) has recently turned 10. I have had him for the entirety of his life, and he’s been fine the whole time until about 9 months ago.
We have always done our best to keep him indoors however he escapes from time to time. Our neighbour of 4+ years often takes him in while we’re at work if he gets out, which is good as he’s not out trying to hunt animals etc. 9 months ago, he was accidentally let out, went over to our neighbour’s place and sat on her couch with her as usual. What was unusual however was when she was patting him as usual, he without any usual warning (flicking tail, noise etc) bit her arm very hard and scratched etc non-stop until her son stopped him and put him outside. He’s never been violent in the past, but this has been the start of ongoing attacks. He is now damaging furniture, scratching at doors, biting my wife and I without provocation/touch, swiping at us as we walk around the house, spraying everywhere indoors (makes a point of coming up to us to spray when we’re sitting down) and constantly crying/yowling. He doesn’t want any physical touch but seems to crave our attention as always.
We of course took him to our local vet who ran a blood test and urine test, could find nothing physically wrong and suggested it’s possible there’s a new cat prowling in our area causing him to spray to re-establish his domain. There are a few neighbourhood outdoor cats but the usual suspects haven’t changed - we’ve kept an eye out for this. We have also at our vet’s suggestion altered his food to a better brand, which made no difference. The vet prescribed a pill which was meant to improve his mood swings etc, we noticed an extremely minor improvement for about a week but now it’s not making any difference at all.
We’ve bought him treats, made little food puzzles for him, new toys and things to occupy his time which he largely ignores. He has always had regular treatment of flea/deworming medicines, and was desexed very early on.
We are at a complete loss as to what to do. I feel that it’s inhumane to surrender him as my wife and I and our home is all he’s ever known, but at the same time we can’t keep him like this.
We welcome any and all advice you may have to give us.