My 4 year old cat suddenly started marking near the front door (pee sometimes poo). I've got a few cats they have lived together years. I bought an extra litter tray and put it in a separate area. I bought feliway. We recently lot our dog. I'm wondering if its something to do with this as the dog slept near the front door. My cat is healthy no issues. I have tried everything. He using the front door mat indoor. My cat goes in and out via the back door when he wants. I can't figure out why he's started doing it he is neutered.