He is best known for his work on Texas cattle fever, in which he and his colleagues discovered the protozoan agent and its means of transmission by ticks.
The major problems were hog cholera, bovine pleuropneumonia, Texas cattle fever, turkey blackhead, and bovine tuberculosis.
A few years after beginning his work at BAI, Smith turned his attention to Texas cattle fever, a devastating disease that destroyed 90% of herds in some affected areas.
Texas cattle fever greatly harmed the cattle industry in the United States until the beginning of the 20th century.
The increased spread of Texas cattle fever is likely due, at least in part, to the increasing populations of white-tailed deer and other wild ungulates that are spreading cattle fever ticks along the Texas-Mexico border.