1,245 dog names end in -o. Of the ones with a recorded sex, 782 measure male against 57 female. No other ending on this site produces a split anywhere near that, so if you want a name read as male before anyone asks, this is the shortest route to it.
Where the reading comes from
Milo, Bruno, Rocco, Gizmo, Diego. The ending reaches English mostly through Italian and Spanish, where it marks the masculine, and the reading survives the journey even on names that were never Italian or Spanish in the first place.
Two beats, closed hard
823 of the slice has two syllables and 412 is four letters or fewer. An -o is an open vowel that still stops — the mouth ends the word in a fixed position rather than trailing away — which is why these carry across a field better than a name ending in -y.
What it costs
The slice averages 62 registrations each against 70 across all dog names, so it is used slightly under the catalogue rate. The gender reading is not free either: a female dog with an -o name will be taken for male at the vet, every visit, for her whole life.
Are names ending in -o male dog names?
In these registers, overwhelmingly: 782 male against 57 female. That is a record of what owners chose, not a rule about what they should.
Why do so many dog names end in -o?
It marks the masculine in Italian and Spanish and arrives in English on names like Milo, Bruno and Diego. The reading then transfers to names with no Italian or Spanish origin at all.
Can a female dog have a name ending in -o?
57 in this catalogue do. It is unusual enough that people will assume otherwise, which is a thing to decide about rather than discover.
Every count on this site is a tally of real registrations: pet licences and shelter intakes published as open data by New York, Seattle, Austin, Montgomery County, Cambridge, Zurich, Basel and four Australian councils. Popularity here is the average share a name holds across those registers, so a name common in a small city is not buried by one common in a large one. Five of the eleven registers are North American and they supply 86% of the records, so read the ordering as naming in those places rather than worldwide. Browse the whole catalogue or read how the data is put together.