Lewis registers 63 times at rank 1628 on male pets. It's the anglicized form of Louis, Germanic in origin and carried into English via the Norman Conquest. It sits at an interesting crossroads: more solid than Louis on paper, slightly more approachable, and a touch less formal. On a dog, it reads as the kind of name an owner chose because they liked it.
The Solid-Human-Name Register
Lewis is in the same zone as Arthur and Walter: reassuringly normal human names that land well on dogs because they don't try to be dog names. The name doesn't imply athletic prowess, mythology, or irony. The human-name trajectory is at /names/lewis.
Sound and Breed Fit
LOO-iss is two syllables and resolves cleanly. It's easy to call without projecting aggression, which suits gentle, even-tempered breeds: Golden Retrievers, Labradors, Basset Hounds. The name has enough weight to feel real without demanding a dog of any particular size.
The Counter-Reading
Lewis's restraint is its whole identity. Owners who want a name that communicates something specific should look at other options. Owners who simply want a name they like, one that will never embarrass them or require explanation, will find Lewis quietly satisfying for the entire life of the dog.