Jenner has been an Australian newspaper and magazine cartoonist for over twenty years, drawing professionally and non-professionally in both the Australian and US scene in the small amount of time outside his duties as a full-time doctor. His cartoons have featured in the Medical Journal of Australia and Australian Doctor magazine. Doc Rat is also in the British Journal of General Practice. He is currently working in a city general practice, and he adopted the anonymous pen name Jenner as an ethical courtesy. Although a daily strip on the Internet was a new venture for him, his Doc Rat character had been appearing in medical and non-medical magazines for over a decade.