Dogs present a special problem. Built to eat almost anything, dogs have an especially large number of intestinal bacteria to help them digest - about 23 million bacteria per gram* of waste. Due to dogs' high-protein diets, their waste is highly acidic. It is not a fertilizer and can contain 10 times as much fecal coliform bacteria as cow manure, and a whole lot of gross stuff like E. coli, salmonella, and giardia. (From Tallahassee, Florida's Think about Personal Pollution campaign)
Comparison of Bacteria in Various Animal Waste
*A gram is about the weight of a business card.