I think onions can be toxic to dogs but i don't know the amounts you would need to give them to be toxic.
Does the garlic give them bad breathe? In humans you have to eat an awful lot of garlic to give heart protection.
I feed a combination of things, their favourite is cooked prizechoice rabbit. The cats and the dogs go mad for that. They have kibble in with it sometimes and soak up the gravy. They like the lamb too.