When silos cannot be broken: Rethinking integration and coexistence in one health.

One Health is increasingly promoted as a collaborative approach for addressing interconnected challenges across human, animal, and environmental health. Central to this vision is the recurrent call to "break down silos" between disciplines, sectors, and institutions. This article critically examines the assumptions underlying the "breaking down silos" narrative and argues that silos should not be understood solely as barriers to collaboration. They also function as repositories of expertise, accountability structures, and mechanisms that sustain institutional coherence. The analysis explores how institutional, disciplinary, data, geographical, and cultural silos influence One Health practice. Rather than eliminating silos, the challenge lies in developing sustainable bridges that support coordination while preserving specialised expertise. These bridges include technical, relational, and governance mechanisms that sustain collaboration across systems. Ultimately, One Health may be better understood as a process of negotiating productive coexistence across diverse forms of knowledge and governance.