While ACI researchers aspire to design animal-centred technology, they must operate within socio-economic systems that are not necessarily animal-centred. This creates a tension between researchers' endeavour to address the immediate needs of animals in specific situations through technological interventions, on the one hand, and these interventions' wider implications and consequences for the situation and life of various animal stakeholders beyond specific ACI projects, on the other hand. In this paper, we focus on the political nature of ACI, drawing from literature on political interaction design, which argues that designers should work towards social justice. Drawing from political philosophies, we then explore how extending the notion of social justice to animals might help define a political notion of animal centredness in ACI. Finally, through the lens of this notion of animal centredness, we consider the relevance of previously proposed strategies for political interaction design and propose an approach that could support ACI researchers' political engagement in animal-centred design.