From Bulbapedia:
"Fujiwara himself designed Eevee as a "blank slate" for its varied Evolutions; as such, while Eevee has traits of foxes, dogs, and cats, it is not based on any specific animal. Fujiwara also envisioned Eevee as a creature that could exist "in people's memories"; namely, vague memories of seeing a cat or dog-like creature that players might have experienced in their childhood."

:neocat_sad: