I have two senior boars that I got from a friend that couldn't take care of them anymore. One is turning 5 while the other one is turning 6. They have been litter trained all of their life. Or so I thought. They'll sometimes use their litter box and sometimes urinate on the fleece. I ran an experiment on them, by lining their cage with a pee pad. They seemed to urinate on it more than in there litter boxes. i make sure that there litter is clean and it does't seem that they have any bladder issues. I don't know what to do...