Answer:

dog

Answer	Crossword Clue
DOG	Fido, e.g.
DOG	Jack Russell, for one
DOG	Pluto or Lassie

DOG	Pug or boxer
DOG	Go after
DOG	Odie
DOG	Drug-sniffer, perhaps
DOG	Frequent "Too Cute!" animal
DOG	Pooch
DOG	Follow closely
DOG	Boxer, for one

DOG	Track relentlessly
DOG	Bother persistently
DOG	Follow relentlessly
DOG	Trail persistently
DOG	Subject of Pavlov's research?
DOG	Bone exhumer, possibly
DOG	Chinese-zodiac animal
DOG	Pursue relentlessly

DOG	Lab, e.g.
DOG	Lucky one?
DOG	Guard or show follower
DOG	Kennel denizen
DOG	Retriever, e.g.
DOG	Lab or peke
DOG	Loaf, with "it"
DOG	"Man's best friend"

DOG	Underperforming investment, slangily
DOG	Follow persistently
DOG	Hound
DOG	Lab, for one
DOG	Stay close behind
DOG	Fetch player
DOG	Boxer or pug
DOG	Cat chaser

DOG	Worthless thing, in slang
DOG	Flop
DOG	Follow
DOG	Ball game treat
DOG	Tail tirelessly