This study investigates human-animal relations in sustainability education. To understand what educational relationships and boundaries are challenged and/or strengthened in education promoting future sustainable societies, we argue that educational theory and practice must move beyond the anthropocentric framework's sole focus on relationships between humans. Drawing on focus group interviews with teacher instructors at eight Swedish universities, we discuss cases in which sustainability education benefits from being understood as crafted via human-nonhuman relations. By concentrating on human-animal relations, we discuss the political and ethical implications arising from relationships being created in certain ways and not others. The empirical examples illustrate how the relations between teacher instructors and various animals can be a critical starting point for understanding the limitations and possibilities fostered by sustainability education.