A watchdog originally referred to a dog's job, but now has been used in additional contexts with the same implication of watching or safeguarding:

• For the dog's job, see guard dog.
• In computer programming there are watchdog timers.
• A watchdog is also an informal name given to consumer protection organisations or campaigners. Their aim is to highlight criminality and poor service provided by companies and public bodies. In the UK, there is a long-running BBC TV programme called Watchdog that fills such a role.