
Dogs are the ultimate scavengers, they can survive on just about anything. A dog could survive just eating rich tea biscuits it's entire life :-) However for optimum health and well being most would agree a balanced diet is important. Tripe is a good food, better than almost anything else if your dog was just to eat one thing, but I'd still rather it had other food too.
My silken bitch, (was picky princess) would often go months with only eating a spoonful of tripe a few times a day, sometimes nothing at all for days, she was very very thin, clapped in between all her ribs but she survived. Now she is spayed, eats a varied, balanced diet and looks wonderful.