September 15, 2020
Gordon Theilen, pioneer of oncology, dies at 92
Dr. Gordon Theilen, an emeritus professor at the University of California-Davis School of Veterinary Medicine, died June 30 at 92.
Dr. Theilen (UC-Davis ’55) was a veterinary comparative scientist and a pioneer in veterinary clinical oncology. He worked at the veterinary school for 37 years and researched cancer-causing viruses in horses, cows, turkeys, cats, and primates. He identified several viruses, including simian sarcoma virus in 1971, and co-authored one of the first comprehensive reference books on veterinary oncology, “Veterinary Cancer Medicine.” His research helped advance cancer medicine and treatments for animals and humans in areas such as chemotherapy, radiotherapy, and immunotherapy.
Dr. Niels C. Pedersen, emeritus professor at UC-Davis, said Dr. Theilen was a man of great vision.
“Gordon was one of a handful of key academics in the U.S. who started to specialize in oncology,” said Dr. Pedersen, who earned his veterinary degree from UC-Davis in 1967 and was a former student of Dr. Theilen. “As a student, we tended to believe that cancer was not treatable by any means other than surgery, and even then, it was largely a disease to diagnose and euthanize. Gordan was questioned by many of his colleagues for his novel belief that cancer in animals was potentially treatable.”
During his career, Dr. Theilen served in several fellowships at the National Cancer Institute and the Chester Beatty Institute in London. He was the first president and a founding member of the Veterinary Cancer Society. The American Association for Precision Medicine awarded him with the Distinguished Emeritus Award for Excellence in Veterinary Oncology in 2019.
“Gordon achieved many awards and accolades during his career, evidencing his importance to comparative and veterinary oncology, and will be missed by those of us that had the pleasure of his friendship, mentoring, and collaborations,” Dr. Pedersen said.
Dr. Theilen also served in the Army shortly after World War II. He recently published two books documenting his journey in his early life and in veterinary oncology: “The Boy with the Wounded Thumb” and “One Medicine War on Cancer.” He was an honor roll member of the AVMA.
He is survived by his daughter, Ann Theilen Yeo; seven grandchildren; and four great-grandchildren.
UC-Davis has established the Dr. Gordon Theilen Endowed Fund which will help train young veterinary oncologists.