I have a 9 week old Labrador puppy who picks up pieces of rock chippings/ gravel when he goes outside for a potty break, which is many times a day. Is he likely to swallow one or just doing his puppy thing of taking anything and everything into his mouth. Trouble is virtually all of my back yard is this gravel. Will he grow out of it. At the moment I can sometimes distract or persuade him to drop it or open his mouth with some difficulty. Any suggestions welcome.