Mathijs Theelen is a Specialist in Equine Internal Medicine (Dipl. ECEIM).
He is assistant professor at the Department of Equine Sciences at Utrecht University. Mathijs works at Utrecht University Equine Hospital treating horses with different medical problems. He is also coordinator of the Neonatal Foal Intensive Care Unit. In his clinical work he focusses mainly on neonatology, gastroenterology, hepatology and geriatrics. In collaboration with the Department of Infectious Diseases and Immunology (Clinical Infectiology) of Utrecht University Mathijs is also working on his PhD project. His research focusses on antimicrobial resistance and antimicrobial susceptibility patterns of bacteria isolated from foals and adult horses and the gut microbiome of horses. Part of his research is conducted at the University of California, Davis, USA. Mathijs has (co)-authored several publications in equine neonatology and gastroenterology.