Every list of popular pet names is somebody's ranking. The question worth asking is what it ranks. This one ranks the share of real registrations a name holds, averaged across eleven public registers, so a name common in Basel is not buried by one common in Austin just because Austin is larger.
That correction matters more than it sounds. Before it, the top of this catalogue read Lucky, Princess, Penny, Cooper — an artefact of which city published the biggest file. Measured as a share, the top reads Luna, Bella, Charlie, Max, which is what pet naming actually looks like.
Popular is a trade-off, not a recommendation
A common name is easy to say, easy for a vet to spell back, and instantly understood — and it means three dogs turning round in the park. Nothing in the data tells you which of those matters more to you. That part is yours.
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 three 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. Nine of the eleven sources are North American, so read the ordering as naming in those places rather than worldwide.