Cave canem, "beware the dog," was famously inscribed at entrances to Roman homes. In poetry, this warning appears literally and metaphorically, signaling danger, aggression, or protected territory. Poets employ it when marking boundaries, when announcing defenses, or when humorously threatening intruders. The phrase suggests both genuine menace and performative bravado, warning that can be either serious or ironic. It appears in poems about guardianship, territory, and threshold, where speakers position themselves or others as sentinels protecting what lies beyond, using the formula to claim authority while perhaps acknowledging the comedy of such claims, the gap between threatening posture and actual power.

Cave canem was famously inscribed in mosaic at Pompeii entrances, warning visitors of guard dogs. The phrase migrated from literal warning to metaphorical threat, marking defended territory and boundaries not to be crossed. Poets use it when claiming personal space, when warning readers they enter at their own risk, when positioning themselves or others as guardians. The phrase can be serious threat or ironic performance—speaker claims ferocity they may not possess. Related to threshold symbolism, the guardian figure, and questions about who gets to mark boundaries and exclude intruders. Useful for understanding poems about privacy, possession, and the violence (real or rhetorical) used to maintain borders. Contemporary poets sometimes use cave canem playfully, acknowledging both the absurdity and necessity of defending psychic territory in a culture of constant exposure.