I've bought new cat boxes and tried different litter, but nothing has worked. The box is cleaned daily and he pees in it without a problem, so I'm at a loss. He usually goes on the bath mats in front of the sink or toilet. So I picked up the mats and he still goes in the same spots without the mats, even after scrubbing the floor with bleach alternative. He's been to the vet recently for a check up and the vet said he was very healthy, but was on the "high end of normal" for hyperthyroidism and a little tartar on his teeth. We do have another cat in the house, but they've been living together for over 12 yrs and have always been friendly and play, run, etc. together regularly. He gets LOTS of attention, special cat milk for older cats, quality food and there is almost always someone around except when we're at work. I know he's old, so is it possible he's getting senile?