* Most in the world: There are likely many people who own a large number of dogs, but there isn't an official record of who has the most.
* Most famous: People like the Queen of England, Martha Stewart, and Oprah Winfrey are known for their love of dogs, but again, it's hard to say who has the most.
* Most in a specific category: There are many dog breeders who have a large number of dogs, especially those who breed certain breeds known for their large litters.
If you have a specific kind of "most" in mind, please let me know and I'll try to find more information!