RIDE HERD ON

v. phr. 1. To patrol on horseback around a herd of animals to see that none of them wanders away. Two cowboys rode herd on the cattle being driven to market. 2. informal To watch closely and control; take care of. A special legislative assistant rides herd on the bills the president is anxious to have congress pass. Mary rode herd on the small children walking home from school to keep them from running into the street.