This article contributes to the literature on One Health and public health ethics by expanding the principle of solidarity. We conceptualise solidarity to encompass not only practices intended to assist other people, but also practices intended to assist non-human others, including animals, plants, or places. To illustrate how manifestations of humanist and more-than-human solidarity may selectively complement one another, or collide, recent responses to Hendra virus in Australia and Rabies virus in Canada serve as case examples. Given that caring relationships are foundational to health promotion, people's efforts to care for non-human others are highly relevant to public health, even when these efforts conflict with edicts issued in the name of public health. In its most optimistic explication, One Health aims to attain optimal health for humans, non-human animals and their shared environments. As a field, public health ethics needs to move beyond an exclusive preoccupation with humans, so as to account for moral complexity arising from people's diverse connections with places, plants, and non-human animals.