In Memoriam

RIP Dr. Timothy O’Brien

Dr. O'Brien: UC Davis Professor of Radiology and Diplomate, ACVR

We are saddened to announce the passing of Dr. Timothy O’Brien on July 26th ,2021. Professor of Radiology and Diplomate of the American College of Veterinary Radiologists (ACVR), Tim served on the University of California, Davis faculty for 39 years. After receipt of a DVM from the University of Illinois (’65), he completed an internship at Washington State University, and then MS (’67) and PhD (’69) degrees in radiology and radiation biology at Colorado State University. In 1969, Tim joined the UC Davis faculty as an Assistant Professor of Veterinary Radiology and Assistant Research Radiologist in the Radiation Biology Laboratory and obtained ACVR specialty board certification.

A tireless champion for the UC Davis Veterinary School’s growth and its reputation, Tim served as Associate Dean for Student Services, and then for more than a decade as Chair of the Department of Radiological Sciences, and later as Chair of Surgical and Radiological Sciences. Throughout much of his early career, Tim was also Service Chief and Director of the residency program for Radiology. Under his leadership, Radiological Sciences at UC Davis evolved to add faculty expertise in radiation therapy, nuclear medicine, ultrasonography, and cross-sectional imaging (CT, MRI) and the residency program expanded, becoming recognized as a premier veterinary diagnostic imaging training program globally.

Initially as one of three faculty radiologists, Tim provided interpretation for small and large animal patients. Drawing on his clinical experiences, he wrote the first veterinary radiology reference text on abdominal disorders in 1978 – Radiographic Diagnosis of Abdominal Disorders in the Dog and Cat: Radiographic Interpretations, Clinical Signs, Pathophysiology. However, an expanding equine caseload honed his early career interest in equine orthopedic disease, and he quickly developed expertise in equine imaging, devoting most of his career to understanding equine musculoskeletal disease through improved imaging techniques and studying the pathophysiology of joint disease. Highlights of his scholarship were development of special projections to evaluate disorders of the carpal, navicular, and pedal bones, and the fetlock, stifle, and tarsal joints of horses. Many of the radiology, equine surgery, and equine medicine residents he mentored in clinical research became faculty at UC Davis and other north American and international veterinary schools.

Tim was passionate about continuing education and improving the quality of equine radiographs, and devoted countless hours to preparing and delivering the highly acclaimed Equine Lameness Panel at the American Association of Equine Practitioners (AAEP) annual meeting. In 1979, with his wife Janet, he founded and directed for more than 4 decades, the popular annual Lake Tahoe Equine Disease Conference. After the death of the School’s long time farrier, Tim established the School’s first named lecture in 1987, the Charles Heumphreus Memorial Lectureship, and raised the funds to endow this free continuing education program for farriers. In 2005, he published a monograph O’Brien’s Radiology for the Ambulatory Equine Practitioner written to guide the acquisition of high-quality radiographic images of equine limbs. The AAEP recognized Tim’s contributions to the profession with their 2008 Distinguished Educator (Academic) Award.

Throughout his career, O’Brien was a strong proponent for the importance of research, serving for many years on the UC Davis Equine Research Laboratory (now, Center for Equine Health) Scientific Advisory Committee and nationally, on the Grayson-Jockey Club Foundation Scientific Committee, including 5 years as Chair.

Tim was devoted to his wife, Janet, sons – Michael (an MD Interventional Radiologist) and Shawn (deceased) – and his grandchildren, Christina, Kelly, William and Sophia, all of whom he loved dearly.

We celebrate Tim’s accomplishments and are saddened by his loss. Our thoughts are with his family at this time. Memorials may be made in Tim’s memory to the Charles Heumphreus Memorial Lecture online at: or by check payable to the UC Regents and mailed to UC Davis School of Veterinary Medicine, Office of Advancement, PO Box 1167, Davis, CA 95617 with a notation on the memo line ‘IMO Tim O’Brien’.

Dr. Erik R. Wisner

Dr. John Pascoe