Guard dog on a Roman mosaic. Object dated to the 1st century CE. The ancient Romans valued sharp dogs, but it was recommended to breed animals that were obedient to the household and not to exaggerate the dog’s militancy.
Columella, a 1st-century Roman writer who wrote about animal husbandry, believed that a guard dog should deter a potential thief with its fearsome appearance and menacing posture, not actual militancy. He recommended black ointment because during the day this colour gives the animal a deterrent appearance, and at night it makes it invisible to uninvited guests.
Before entering the house, the Romans often placed signs on the walls reading Cave Canem (“Beware of the dog”), often decorated with a black animal with bristling hair and baring fangs.
