Nikki ranks #311 with 374 entries and skews strongly female. It is the kind of pet name that feels lifted directly off a friend's contact list: short, breezy, and built on the same -i ending that has dominated American nicknames since the 1970s.
A nickname doing full-name duty
Nikki started as a clipped form of Nicole or Nicholas and stayed there in human use, but pet owners promote it to the official name without hesitation. The Prince song Darling Nikki (1984) gave the spelling a faint pop-culture anchor for a certain generation, though most current adopters are not consciously referencing it. Nikki Minaj has reintroduced the name to a younger cohort with a different valence.
Sound fit and breed lean
Two syllables (NIK-ee), hard-K stop, ending on the universal pet-friendly -ee. Recall on a leash is strong because the K cuts through ambient noise. Small companion breeds tend to wear it well, and Chihuahuas and small mixed terriers come up often.
The not-so-soft counter-reading
Nikki reads as casual and unfussy, which is part of its appeal, but it lacks the gravitas some owners want for a larger or more dignified dog. Owners drawn to Nikki for a Great Dane or Shepherd often report cycling back through more formal options before returning. The human Nikki page shows the name peaking in the 1970s-80s on the SSA chart, which fits its current pet-naming demographic.