It has now been satisfactorily proven that the dog was named after the planet, rather than the other way around. So, one is vindicated.
Englishwoman Venetia Phair • Who, as an 11-year-old girl, named the planet Pluto in 1930. She named the planet for the Roman god of the underworld and suggested it to her grandfather, who talked to some people, and then they talked to more people, and eventually, the name stuck. Phair died April 30 at 90. • source