G Mark Johnston is a veterinary surgeon, business leader, and advocate for animal and human wellbeing across the global veterinary community. As CEO of Vetstream, he oversees Vetlexicon, a digital clinical resource supporting veterinary teams worldwide. Under his leadership, Vetstream has introduced an AI tool built exclusively on its own content to provide reliable, evidence-based support.
He is also the founder of the Vets in Mind Alliance, which promotes mental health awareness and offers triage tools to help professionals assess their wellbeing. As Vice President of the ProSalus Foundation (formerly the World Small Animal Veterinary Foundation), Mark contributes to improving animal health and welfare through a One Health approach, including recent work supporting Ukrainian vets facing rising rabies risks.
A Cambridge graduate, Mark began his career in equine anaesthesia and critical care before leading the Confidential Enquiry into Perioperative Equine Fatalities (CEPEF), a landmark international study. Since joining Vetstream in 1995 and becoming CEO in 2006, he has combined clinical insight with digital innovation to enhance care for both animals and the people who treat them.



