New Bolton Center Kennett Square, PA
Emergencies & Appointments:
Ryan Hospital Philadelphia, PA


Diplomate, American College of Veterinary Internal Medicine (Oncology)

Associate Professor of Clinical Oncology, University of Pennsylvania School of Veterinary Medicine

Director of Oncology Clinical Trials, University of Pennsylvania School of Veterinary Medicine

Clinical Specialties: clinical trials, clinical research, cancer, osteosarcoma, immunotherapy
Research Areas: canine osteosarcoma, cancer pain, immunotherapy, chemotoxicity, chemotherapy mechanisms of action
PubMed Link
Contact Information:
Hill Pavillion - PennVet
380 S. University Ave.

The current focus of my research is based on translational models of naturally occurring cancer in companion animals. Specifically, I focus on chemotoxicity and chemotherapy mechanisms of action, improving chemotherapy efficacy with novel combination protocols or investigational drugs, improving the treatment paradigm for canine (and thereby human) osteosarcoma, and understanding and treating cancer pain.

Oncology clinical trials, especially in canine osteosarcoma and cancer pain.

Reising, A. J., Donnelly, L. L., Flesner, B. K., Maitz, C. A., Bryan, J. N. Solitary osseous plasmacytomas in dogs: 13 cases (2004-2019) Journal of Small Animal Practice : , 2021.

Musser, M. L., Curran, K. M., Flesner, B. K., Johannes, C. M. A retrospective evaluation of chemotherapy overdoses in dogs and cats Front Vet Sci 8: 718967, 2021.

Middleton, J. R., Getchell, R. G., Flesner, B. K., Hess, W. J., Johnson, P. J., Scarfe, A. D., Starling, D. E. Considerations related to the use of molecular diagnostic tests in veterinary clinical and regulatory practice Journal of the American Veterinary Medical Association 259: 590-595, 2021.

LeBlanc, A. K., Mazcko, C. N., Cherukuri, A., Berger, E. P., Kisseberth, W. C., Brown, M. E., Lana, S. E., Weishaar, K., Flesner, B. K., Bryan, J. N., Vail, D. M., Burton, J. H., Willcox, J. L., Mutsaers, A. J., Woods, J. P., Northrup, N. C., Saba, C., Curran, K. M., Leeper, H., Wilson-Robles, H., Wustefeld-Janssens, B. G., Lindley, S., Smith, A. N., Dervisis, N., Klahn, S., Higginbotham, M. L., Wouda, R. M., Krick, E., Mahoney, J. A., London, C. A., Barber, L. G., Balkman, C. E., McCleary-Wheeler, A. L., Suter, S. E., Martin, O., Borgatti, A., Burgess, K., Childress, M. O., Fidel, J. L., Allstadt, S. D., Gustafson, D. L., Selmic, L. E., Khanna, C., Fan, T. M. Adjuvant sirolimus does not improve outcome in pet dogs receiving standard-of-care therapy for appendicular osteosarcoma: A prospective, randomized trial of 324 dogs Clin Cancer Res 27: 3005-3016, 2021.

Harrison, N. J., Shumway, K. L., Hansen, S. A., Maitz, C. A., Thombs, L. A., Flesner, B. K. A 3D-printed apparatus for imaging multiple rats simultaneously Comparative Medicine 71: 116-122, 2021.

L. Ashworth H, K. Flesner B, J. Norquest C, A. Maitz C Nasal angiofibroma treatment outcome using intensity-modulated radiation therapy in a dog Veterinary Radiology & Ultrasound 62: e40-e43, 2021.

Weissman, Marc, Donnelly, Lindsay L, Branson, Keith, Glahn, Anastasia, Nagy, Dusty, Havis, Brett, Johnson, Gayle, Flesner, Brian K Electrochemotherapy for a cutaneous squamous cell carcinoma in a Vietnamese pot-bellied Pig (Susscrofa) Journal of Exotic Pet Medicine 34: 37-43, 2020.

Flesner, B. K., Wood, G. W., Gayheart-Walsten, P., Sonderegger, F. L., Henry, C. J., Tate, D. J., Bechtel, S. M., Donnelly, L. L., Johnson, G. C., Kim, D. Y., Wahaus, T. A., Bryan, J. N., Reyes, N. Autologous cancer cell vaccination, adoptive T-cell transfer, and interleukin-2 administration results in long-term survival for companion dogs with osteosarcoma Journal of Veterinary Internal Medicine 34: 2056-2067, 2020.

Dedeaux, A. M., Flesner, B. K., Reinhart, J. M., Langohr, I. M., Husnik, R., Geraci, S. N., Taboada, J., Rademacher, N., Thombs, L. A., Bryan, J. N., Trepanier, L. A., Boudreaux, B. B. Biochemical, functional, and histopathologic characterization of lomustine-induced liver injury in dogs American Journal of Veterinary Research 81: 810-820, 2020.

Schaefer, E. A. F., Chu, S., Pearce, J. W., Bryan, J. N., Flesner, B. K. Papillomavirus DNA not detected in canine lobular orbital adenoma and normal conjunctival tissue BMC Veterinary Research 15: 226, 2019.

Flesner, B. K., Fletcher, J. M., Smithee, T., Boudreaux, B. Long-term survival and glycemic control with toceranib phosphate and prednisone for a metastatic canine insulinoma Journal of the American Animal Hospital Association 55: e55105, 2019.

DVM (Veterinary Medicine) University of Illinois, 2010

MSc (Medical Oncology) University of Missouri, 2014

Diplomate, American College of Veterinary Internal Medicine (Oncology)

Veterinary Specialty Hospital-San Diego (2010 to 2011)
Rotating Internship

University of Missouri (2011 to 2014)
Residency in Medical Oncology