Lord appears 68 times at rank 1,539 on male pets — a title used as a name, which is a specific and somewhat grand choice. It sits in the same territory as Duke, Earl, and Baron: aristocratic titles repurposed as first names, applied to dogs who may or may not have the bearing to justify them.
The Title-as-Name Tradition
Duke has been one of America's most enduring dog names for decades, and Lord occupies the tier just above it in the aristocratic hierarchy — which means some owners are quite deliberately choosing the senior title. The gesture is usually affectionate hyperbole: the dog is not, in fact, a lord, but calling him one is a form of devotion. Great Danes, Irish Wolfhounds, and regal large breeds carry Lord with appropriate gravitas.
Pop Culture Check
Lord Farquaad from Shrek, Lord Voldemort, and various villainous lords across fiction all deposit associations with the title that owners may or may not be invoking. A sinister-looking black cat named Lord has a specific energy. A fluffy golden dog named Lord has a different one. The name is flexible enough to absorb both readings without collapsing.
Standalone Viability
Unlike Baron or Duke, Lord rarely functions as a human given name — the human name page at /names/lord shows minimal SSA data — which makes its pet use feel deliberate and specific. It's a name chosen for effect, and the effect is usually achieved. Browse similar title names at pet-names.