Since I've had my bunny, since May, he's used a regular rectangle pet litter pan. With the pellet litter. I clean it out every to every other day. I've noticed as his winter fur has grown in he has tufts of fur on his bum and little mats....I assume some mats are normal. I'd rather not give him a bath (setting him water just covering his bum). Was going to see if the vet could brush them out or something when I bring him in for his nail clipping. He hates being touched on his bum or being picked up in general and really struggles. So this is why I bring him to the vet for nail clipping, less stress on both of us and it's all done in like 3 mins. for rather cheap. Should tufts and mattes be a concern? His poops are healthy looking, and no actually poops is stucked or smooshed to his bum.