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


Diplomate, American College of Laboratory Animal Medicine (DACLAM)

Associate Professor, Pathobiology, University of Pennsylvania School of Veterinary Medicine

Research Areas: Laboratory Animal Medicine,
PubMed Link
Contact Information:
176 EG Old Vet Quadrangle
3800 Spruce Street

My research goals are to improve the care and use of mice in biomedical research. This has taken on two distinct lines of investigation. First, is in the improvement of anesthesia in mice. While this is a common procedure, when we critically evaluate murine anesthesia, we see that we are well behind the level of care being provided for our other veterinary species. My research in this area, along with that of several other research groups, is elevating our anesthetic care for mice by: 1) increasing the number of anesthetic protocols available to researchers, 2) reporting normal values for mice under different anesthetic protocols, enabling people to more effectively monitor anesthesia in mice, 3)beginning to look into interventions when mice are not responding normally to an anesthetic and 4) looking into the care of mice after the procedure, when anesthetic deaths are at their highest.

The second line of research involves improving our understanding, diagnostics and treatment of mice in our facilities. My work has addressed the epidemiology of both opportunistic infections and spontaneous diseases in mice, diagnostic methods and use of antibiotic therapy in mice. My goal moving forward is to continue to advance mouse medicine by bringing evidence based medicine into mouse care.

As a diplomat of the American College of Laboratory Animal Medicine, my clinical specialty is in the care and use of animals used in biomedical research. Being at the University of Pennsylvania, I have had the opportunity to work extensively with many of the species commonly used in biomedical research including: Mice (which are the main focus of my research), dogs and cats with genetic diseases, sheep and pigs in cardiovascular models, rabbits in both urologic and orthopedic studies, marmosets in learning studies, rats in neurologic studies, gerbils being used as a host of parasites and countless other animal models.

Marx, J. O., Brice, A. K., Boston, R. C., Smith, A. L. Incidence rates of spontaneous disease in laboratory mice used at a large biomedical research institution J Am Assoc Lab Anim Sci 52: 782-791, 2013.

Caro, A. C., Hankenson, F. C., Marx, J. O. Comparison of thermoregulatory devices used during anesthesia of C57BL/6 mice and correlations between body temperature and physiologic parameters J Am Assoc Lab Anim Sci 52: 577-583, 2013.

Jaber, S. M., Hankenson, F. C., Heng, K., McKinstry-Wu, A., Kelz, M. B., Marx, J. O. Dose regimens, variability, and complications associated with using repeat-bolus dosing to extend a surgical plane of anesthesia in laboratory mice J Am Assoc Lab Anim Sci 53: 684-691, 2014.

Marx, J. O., Vudathala, D., Murphy, L., Rankin, S., Hankenson, F. C. Antibiotic administration in the drinking water of mice J Am Assoc Lab Anim Sci 53: 301-306, 2014.

Marx, J. O., Basha, M. E., Mohanan, S., Hypolite, J. A., Chang, S., Wein, A. J., Zderic, S. A., Laping, N. J., Chacko, S. Effects of Rho-kinase inhibition on myosin light chain phosphorylation and obstruction-induced detrusor overactivity Int J Urol 21: 319-324, 2014.

Allen-Worthington, K. H., Brice, A. K., Marx, J. O., Hankenson, F. C. Intraperitoneal Injection of Ethanol for the Euthanasia of Laboratory Mice (Mus musculus) and Rats (Rattus norvegicus) J Am Assoc Lab Anim Sci 54: 769-778, 2015.

Marx, J. O., Jensen, J. A., Seelye, S., Walton, R. M., Hankenson, F. C. The Effects of Acute Blood Loss for Diagnostic Bloodwork and Fluid Replacement in Clinically Ill Mice Comp Med 65: 202-216, 2015.

Erickson, R. L., Terzi, M. C., Jaber, S. M., Hankenson, F. C., McKinstry-Wu, A., Kelz, M. B., Marx, J. O. Intraperitoneal Continuous-Rate Infusion for the Maintenance of Anesthesia in Laboratory Mice (Mus musculus) J Am Assoc Lab Anim Sci 55: 548-57, 2016.

de Souza Dyer, C., Brice, A. K., Marx, J. O. Intraperitoneal Administration of Ethanol as a Means of Euthanasia for Neonatal Mice (Mus musculus) J Am Assoc Lab Anim Sci 56: 299-306, 2017.

Erickson, R.E., Blevins, C.E., DeSouza-Dyer, C., Marx, J.O. Alfaxalone-Xylazine Anesthesia in Laboratory Mice (Mus musculus) J Am Assoc Lab Anim Sci 58: 30-39, 2019.

Davis, J.N., Greer, W., Banks, R.E., Philips, B.H.,Marx, J.O. Postapproval Monitoring Practices at Biomedical Research Facilities J Am Assoc Lab Anim Sci : , 2019.

Wallace, C. K., Bright, L. A., Marx, J. O., Andersen, R. P., Mullins, M. C., Carty, A. J. Effectiveness of Rapid Cooling as a Method of Euthanasia for Young Zebrafish (Danio rerio) J Am Assoc Lab Anim Sci 57: 58-63, 2018.

Nelson, F. E., Hollingworth, S., Marx, J. O., Baylor, S. M., Rome, L. C. Small Ca(2+) releases enable hour-long high-frequency contractions in midshipman swimbladder muscle J Gen Physiol 150: 127-143, 2018.

Hankenson, F. C., Marx, J. O., Gordon, C. J., David, J. M. Effects of Rodent Thermoregulation on Animal Models in the Research Environment Comp Med : , 2018.

Marx, J. O., Gaertner, D. J., Smith, A. L. Results of Survey Regarding Prevalence of Adventitial Infections in Mice and Rats at Biomedical Research Facilities J Am Assoc Lab Anim Sci 56: 527-533, 2017.

BS (Animal Science) Cornell University, 1988

DVM (Veterinary Medicine) NYSCVM, 1991

PhD (Kinesiology) The Pennsylvania State University, 2001

Diplomate, American College of Laboratory Animal Medicine (DACLAM)

University Laboratory Animal Resources University of Pennsylvania (2006 to 2008)
Laboratory Animal Medicine Residency

University of Pennsylvania (2003 to 2006)
Post Doctoral Fellow