I have a 13 year old neutered Tom. The last two mornings I have come downstairs to a kitchen stinking of cat pee. He has never peed anywhere but outside or in the litter tray before. His catflap is locked overnight so it isn't another cat. He has access to a litter tray.
Any ideas why he has suddenly started to do this? He is his usual self in all other ways and doesn't appear ill at all. He's due his annual jabs next week so I will obviously mention it to the vet then, but any advice would be much appreciated. Thanks