Sardines! So much so that I found the empty tin with teeth marks in it on the side. I called him in and pulled his lips up and got him to open his mouth while I ran my finger along his gums and checked all around. Thankfully he didn't cut himself, but there were actually teethmarks going right through the tin! 5 minutes later I realised that I just put my hand into a dogs mouth that I've only known a week.