That happens to my Dexter, his coat is cottony so the hairs are VERY fine and mat super easy. They will come out like that in a 'chunk' when I brush him... I would suggest you have your baby groomed and bathe her regularly. Also brush those areas whether she lets you or not. You have to teach her to get used to being brushed in all areas. Mats are uncomfortable and can be painful, also if they are in too long they can cause sores to the skin underneath. My Dexter HATES being brushed so I keep him in a puppy cut and bought clippers (finally) so I can keep up with it myself. It needs to be done every 8 - 10 weeks for him to not mat up like that!
