Mark Lynn Byrum, DVM, Residency-Trained in Oncology

Medical & Radiation Oncology


University of Illinois College of Veterinary Medicine


Purdue University College of Veterinary Medicine


University of Illinois College of Veterinary Medicine

Professional Memberships

Unlike some people, Dr. Mark Byrum didn’t have a single defining moment that drew him into veterinary medicine. As he progressed through his education, he found that veterinary medicine was a limitless opportunity that combined new and exciting day-to-day experiences, science, and communication opportunities.

How did you become interested in oncology?

Ever since I was a child, cancer has always been generalized. I think that we tend to end the sentence at cancer and do not truly understand what that means for a person or a pet. Cancer is not just a one-note statement. Being a part of veterinary oncology allows me to help clear up those misconceptions about cancer and provide help for dogs and cats affected by cancer.

What is your philosophy of patient care?

Patient care starts with looking at your patient and working towards understanding where their needs are. In the medical field, we are always trying to establish a problem list and treatment plans as if we are taking a standardized test, which is not what being a doctor is about. Our job is to take our medical training, apply it clinically, and tailor treatments to the needs of our patients.

What are some of your biggest challenges in your area of expertise?

Veterinary oncology is a challenging field because we often have to break the bad news. My job as a veterinary oncologist is to effectively communicate what the pet’s health problem means and help my clients navigate the various treatment options to provide the best possible quality of life.

Is there a particular case that inspires or motivates you?

One of my favorite patients of all-time centers on this amazing Cornish Rex named Cleocatra. She was a particularly remarkable case because she had a stack of health issues (13 to be exact) and one of those happened to be a cancerous process. Everyone was very doom and gloom about her disease and skeptical about moving forward with treatment. Cleocatra fooled everyone and had a fantastic, durable response with treatment! This case just highlighted how patients with tremendous disease burdens should not be neglected treatment and that I get to work with fantastic, motivated owners who love their pets!

What do you like to do outside of work?

When I have the time, I’m always up for live music, great restaurants, and fun in the community. Additionally, I enjoy running! Most important out of everything is that I love spending as much time with my dog Brutus (he’s a perfect Vizsla). We like to run, hike, or go hang outside at a café. I’ve always lived in Central Illinois and am looking forward to many adventures in Chicago and the Chicagoland area!


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