This article addresses two concepts that are quite widespread among Latin American cultures: susto or “‘fright sickness,” and the “masters of the animal species” philosophy, whereby individual animal spirits are believed to be “owned” by species-specific spiritual masters. This is the first article to integrate both these aspects, drawing from ethnographic data from the Trinitario people in Bolivia collected through participant-observation and semistructured ethnobotanical interviews on medicinal plants. Although Trinitarios have a long history of agriculture, their worldview is still partly one of animistic hunter and fisherman societies. This worldview is reflected in Trinitario susto etiology and treatment. Susto is locally believed to originate through soul theft by a variety of masters of the animal species and landscape spirits. Treatment is partly based on the principle of similia similibus curantur or “like cures like” and magicoritual ceremonies, but ethnopharmacological preparations are also well known and frequently used.