You cannot be too careful of your teams; on their condition depends entirely your success in getting through to the Pacific coast, warned Philip L. Platt and N. Slater in their 1852 Travelers\u27 Guide across the Plains upon the Overland Route to California.1 The diaries, letters, and guidebooks written by the emigrants who crossed North America on the overland trails during the mid-nineteenth century reveal a new awareness of the animals that journeyed with them. Often written as advice to those who might follow them, the travelers worried about their animals in ways beyond what theologians and philosophers would have expected or anticipated. Borne out of the need to get to California, Oregon, or Utah safely, emigrants learned a new stand...