In 1793, the U.S. Mint at Philadelphia paid $3 for the watchdog named Nero. The expenditure, recorded in a handwritten ledger as “For a Dog for the Yard,” is sandwiched between a $1 payment to “Thomas Dobson for an Inkstand & Folder” and a $2.40 payment to “Jacob Kinnard for Sundries.”
Over the next 25 years, further expenditures of food
and license tags for Nero and his successor watchdogs were recorded.
A night watchman was required to visit all sectors of the Mint premises every hour, and Nero trailed along with him. The dog supposedly took over full responsibility if the watchman was absent. Only the night watchman was allowed to feed Nero, because the Mint didn’t want the dog getting friendly with anyone else.
An ancient Treasury seal, which disappeared from documents long ago, presents other evidence of the “Watchdog of the Treasury.” Within a wreath around the seal’s edges is a symbolic strongbox. Lying beside the strongbox is a capable looking watchdog with his left front paw securely clasping a large key. The seal bears the lettering, “U.S. Treasury.”
— Source: United States Department of the Treasury