I have two great cats that really love each other. the youngest is now a year and a half, I adopted him when he was six weeks old, he thought him self to pee in the toilet, I never trained him to do so, but he has serious problems with poop. He poops on the floor three to five times a week. Those times he doesn't like to use the litter box even though we keep it very clean.
Is there a way to make him poop in the litter box or train him to use the toilet?