Indeed, dogs tended to be kept for a specific function during the Roman period, such as guard dogs, watch dogs, or hunting dogs. But there is evidence that they were also kept as pets. Dogs were most often seen as household protectors, and it was said that a dog barking at nothing was a warning of the approach of Trivia, the goddess of graveyards and witchcraft, as dog were always able to sense her presence. Perhaps the most famous visual representation of a dog in Ancient Rome is the ‘Cave Canem’ (“Beware of the Dog”) mosaic, at the entrance to the House of the Tragic Poet in Pompeii.
For more information about the meanings of animals in Roman art, see our relevant blog post: Animal Symbolism in Roman Art.