Trepanier obtained her DVM from Cornell University and completed an internship and residency in small animal internal medicine at the Animal Medical Center in New York. She then earned a doctorate in pharmacology at Cornell. She is a professor of internal medicine and director of clinical research at the University of Wisconsin-Madison School of Veterinary Medicine.
Trepanier manages internal medicine patients; trains students, interns, and residents; and conducts research on the genetic and metabolic basis of drug toxicity. She is board certified in internal medicine and veterinary clinical pharmacology.