To date, there has been little articulation of specific One Health clinical activities for veterinary and human health care providers regarding emerging infectious diseases, yet they could play a critical role. Under current clinical paradigms, both human and animal health professionals routinely diagnose and treat zoonotic infectious diseases in their patients, but tend to work in parallel with little cross-professional communication or coordination of care. For this to evolve toward a One Health model, both types of clinicians need to see how individual cases can be "sentinel events" indicating environmental risk for disease emergence, and develop mechanisms of rapid communication about these risks. Human and animal clinicians also need to take a more proactive and preventive approach to zoonotic diseases that includes the occupational health of animal workers in farms, laboratories, veterinary clinics, and other settings, as well as the recognition of increased risk among immunocompromised individuals in contact with animals. This requires training in One Health clinical competencies including the ability to diagnose and treat zoonotic diseases, implement preventive care interventions for individual patients, provide occupational health services for animal workers, recognize sentinel cases, report cases to public heath and clinical colleagues, and assess and help to intervene with environmental factors driving infectious disease risk in humans and animals. To provide an evidence base for such competency training, there is a need for development and testing of innovative protocols for One Health clinical collaborations.