Cave canem, literally "attention to the dog", is used wisely nowadays as a warning sign at the entrance of the houses to say "watch out for the dog".
The inscription derives from a famous mosaic recalling the canem cave found in the archaeological excavations of Pompeii, on the entrance floor of the Casa del Poeta Tragico (Regio VI, Insula 8, nº 5); in another mosaic, without inscription, where the loppide is represented in the chain near a semi-open door, it is always visible in Pompeii at the entrance to the House of Paquio Proculo (Regio I, Insula 7, nº 1).
Finally, a well-known mosaic, also found in the Casa di Orfeo, is kept in the National Archaeological Museum of Naples.