The muskrat, a charismatic semi-aquatic rodent, has experienced long-term declines across the United States dating back to the 1970s. The factors for this decline remain unclear. Our research will investigate health challenges in eastern US muskrat populations by determining the prevalence and distribution of pathogens and contaminants in these declining animals. The outcomes from our effort can provide context to observed declines and serve as a guide for management efforts of the species.