Willoughby eats his own

I tried putting pineapple in his food for every single meal but it had zero effect. I am about to invest in some of the cophragia (sp) tablets to see if that helps. It's only a problem if I let him out unattended in the garden, otherwise I'm there and pick it right up as soon as he wanders away from it and isn't watching me.
He also eats the cats poo

Soooooo gross! I'd rather not have to keep him on lead in the garden forever, but I don't really see what else I can do. With 2 young boys I can't have him coming straight in and licking their faces/hands with poop breath
