The concept of using dogs to protect sheep and other livestock from predators is an ancient one and can be traced to many centuries B.C. in Eurasia (Bordeaux, 1974). The Spanish conquistadors brought guarding dogs with them to the western hemisphere to help protect their flocks (Lyman, 1844). Darwin (1839) noted that guarding dogs were commonly seen with large flocks of sheep in South America. Despite this long history, with the exception of the Navajo Indians who have used dogs with their sheep and goats since the early 1700's (Black, 1981), the use of dogs to protect livestock in the United States is relatively new.