Mickey ranks at #107 with 966 entries, and the name carries a heavier cultural footprint than almost any other in the top 200. Mickey Mouse arrived in 1928, and nearly a century of saturation means the name comes pre-loaded for every owner whether they want the association or not.
The Disney shadow, mostly accepted
Most pet Mickeys are not consciously named after Mickey Mouse. They are named after a grandfather, a sports figure, or a vague sense that the name is friendly and slightly retro. But the Disney character is unavoidable in the texture, and owners who do not want that association will usually go with Mick or Michael instead. The same texture-vs-source dynamic shaped Oscar and Winston.
One counter-reading: Mickey also has a strong sports-name register from boxing (Mickey Ward), baseball (Mickey Mantle), and various Irish-American athletic contexts. Owners who reach for Mickey for those reasons are usually picking it for sturdy mid-sized dogs rather than for the small mouse-coded breeds.
The breed spread is wide
Mickey lands across small companions, terriers, and mid-sized mixed breeds at roughly comparable rates, which is a broader distribution than most names in this rank tier. The wide spread suggests the name is functioning as a default rather than as a breed-specific aesthetic. Compare with Jack, which occupies a similar default-male slot in the rankings.
The human Mickey is usually short for Michael, which has been a top-20 SSA baby name for decades. The Michael baby name page shows the formal version.