My 1.5 year old cat started missing the litter box when he poos. He'd stand on the edge of the box while he's doing his duty, but then would step off and poo on the floor.
At first i thought he probably needs a bigger litter box (he'd been using the same one since he was a kitten), so we got him a bigger box. But he's still doing the same thing. He'd play with the sand for a bit. Stand on the edge of the box, squats... then as he poos he'd step off the edge and on to the floor.
What gives???