Place names are the ones with a story attached before the animal arrives: where you met, where you were living, where the drive home from the shelter went. The registers are full of them, and unlike most naming fashions this one is genuinely durable.
Why the list is short
Because a name only counts as a place name here when the place is recorded — a city, a river, an island someone can point at. Names that merely sound foreign or far away are not in it, which keeps the tag worth something.
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.