Animal health is a cornerstone of public health through provision of animal products, risk of zoonotic infections and the positive impact of animals on our wellbeing. Where synergies exist in disease and treatment modes, it would appear to make a lot of sense to develop diagnostics and therapeutics in concert. This begs the question why is it not more commonplace for biotech to develop co-incidentally in both human and animal health. Liz Barton at Companion Consultancy explores both the benefits and the barriers to a One Health approach in diagnostic and therapeutic research and development.