The college is one of the world's leading specialist veterinary institutions. It is the largest and oldest independent veterinary school in Britain.
McIlwraith expressed his surprise at receiving the award.
Professor Quintin McKellar, principal of the college, noted that the award was conferred on individuals of exceptional academic merit, who have also helped or been associated with the college in one way or another.
"Clearly you fall into both categories and were therefore considered an outstanding candidate," McKellar said.
McIlwraith has received honorary doctorates from the University of Vienna in 1995, Purdue University in 2001, Massey University in New Zealand in 2003 and also from the University of Turin, Italy, in 2004.
McIlwraith received his veterinary degree (BVSc) from Massey University. After time spent in private practice, he did a surgical internship at the University of Guelph in Canada, followed by a surgical residency at Purdue University.
He also completed MS and PhD degrees in the area of joint disease (arthritis) research while at Purdue.
He became board-certified as a Diplomate in the American College of Veterinary Surgeons in 1979 and joined the faculty at Colorado State University that same year. He became a full Professor in 1986.
He is a past-president of the American College of Veterinary Surgeons and the American Association of Equine Practitioners, and a recognised leader in the field of equine orthopaedic research and surgery.
He consults worldwide as a specialist equine surgeon and has received national and international media attention for his contributions to joint research.
He is the author of four textbooks and has authored or co-authored over 250 refereed publications and textbook chapters, and has presented over 350 seminars both nationally and internationally to equine practitioners, veterinary specialty meetings and human orthopaedic meetings.