My cat has started yowling - help!

[fussychica]

About 8 weeks ago my 8 year old neutered tom did a very uncharacteristic thing - he sprayed indoors. Virtually from that moment he makes a terrible noise pretty much whenever he isn't asleep or eating. He has been to the vet who could find nothing wrong with him and suggested nothing .
He has a sister who is quiet and disinterested in this new noise.

He sounds like he has lost something - at first we thought it was when he couldn't see his sister but that's not the case.

It's driving us nutty. Any thoughts?

I'm not an expert but when you said he sounds like he's lost something got me thinking he is calling to something.

The only thing I can think of that may produce that response in a male cat is a female in season. I know you say he has been nutered but maybe he has picked up on it anyway and there is one in the area.

Clutching at straws a bit I know. Before our female got spayed we would have all sorts of toms calling for her. After a few of the young ones still called and took quite some time to realise she wasn't available anymore.

My mums cat started yowling when he went deaf. Can your cat hear you?

Def not deaf - he is pure white so that would have been a good possibility.

The female cat thing - he did spray which he had never done before so that could be the answer. He yowls whether he is in or out - it makes no difference except in it drives me mad and out it could be driving our lovely neighbours mad.

Looking at some old threads people mentioned senility so it looks like he either horny or senile - poor bugger.

Any other thoughts?

My cat started yowling when he lost his hearing and started spraying in one particular spot in the house. The vet said he was spraying (although neutered) because going deaf has left him confused and by spraying he is reassuring himself that it is still his home. Although my mum in law said I would have to have him put down he is still here at the age of 21. Yes, still yowling and still spraying although once every couple of days. Easy to clean up although inconvenient. I would never dream of putting him down as a pet is one of the family.

My cat starting yowling at night because he was hungry. It was so loud it would wake me up even with all the doors shut. He had been fed the usual amounts but just wanted more.

I started giving him a bit more food in the evenings and its stopped now.

My mum's cat has started this and is currently being investigated for thyroid probs as his appetite has incrwased massively.
My elderly female cat did it but it was dementia. She was given medication for high BP which did stop her yowling after a month or so.

Is his tray clean? Ours wees on the curtains if the tray is a bit mucky and needs a wash.