I have three cats, all male, 4 years, 1 1/2 years, and a year old. all litter trained and up until a few weeks ago, i had no issues, with any outside of the litter box happenings. then for some strange reason, my 1 1/2 year old has started pooping right outsied the box. I don't know why, i have two littler boxs and i clean them both twice a day. He does not have the runs, it is normal poop, it's just really starting to frustrate me because i don't know why he's doing it. I've tried showing him what hes done wrong, that didn't work. so at night and during the day when i am not here i locked him in the bathroom and he actually pooped inside the box, but i can't keep locking him up i want him with us. is there anything i can do to stop this, and do you have any idea at all as to why he started??
don't worry this is a common occurrence and i get asked a similar question all the time. It is unlikely that your cat is ill, it is more the case that something has upset him about the litter tray. these things can come out of the blue and can seem quite puzzling to us. the fact that he will use his tray when he is in the locked bathroom suggests that he is having a issue over the litter tray belonging to the other cats. I always recommend that each cat have their own separate litter trays as the scent of the other cats can often put them off. even though you clean them every day the scent may still linger ever so slightly and our cats can pick this up.
I have attached links to my pages about this issue at the bottom of the page, they may help to give you more info on this type of problem.