I have not seen a question like this. Looking at my dog, and the serious personal relationship between man and canine, what is the first example of humans using animals (canines in particular) to defend themselves against other animals? In particular, against other humans. Thanks!
Dogs were domesticated at least 15,000 years ago, when humans were still hunter-gatherers (as opposed to having agriculture). The answer to this question very likely predates history (i.e. written sources). You might try /r/anthropology for better luck.