Off the top of my head, I'd say dried liver. I've seen it in stores, listed/packaged as freeze dried liver, but I've never looked into it.
I can't imagine that it would be that hard to make youself.
He is your friend, your partner, your defender, your dog. You are his life, his love, his leader. He will be yours faithful and true~ to the last beat of his heart. You owe it to him to be worthy of such devotion. ~unknown