Answer:

MUTT

Answer	Crossword Clue
MUTT	Paperless pup
MUTT	Jeff met him in 1908
MUTT	Jeff's tall pal

MUTT	Jeffs partner
MUTT	Jeff's friend
MUTT	Mangy sort
MUTT	Common canine
MUTT	Pound inmate
MUTT	Purebred's opposite
MUTT	Pound hound
MUTT	Mix at the pound

MUTT	Benji, notably
MUTT	Disney's Tramp, for one
MUTT	Jeff's partner
MUTT	Pooch without papers
MUTT	Pup without papers
MUTT	Stray dog, often
MUTT	American Kennel Club outcast
MUTT	"Heinz 57 varieties" dog

MUTT	Jeff's pal
MUTT	"Heinz 57" dog
MUTT	"Heinz 57" pooch
MUTT	Pooch without papers, perhaps
MUTT	Mangy cur
MUTT	Mixed breed
MUTT	Pound pick, probably
MUTT	Canine with a questionable lineage

MUTT	Kennel club reject
MUTT	It has no papers
MUTT	No Westminster contender
MUTT	Rescue dog, usually
MUTT	Unlikely dog show winner
MUTT	Mongrel
MUTT	Mixed-breed pooch
MUTT	Pooch sans papers

MUTT	Many a shelter resident
MUTT	Mixed-breed dog
MUTT	Dog of many breeds
MUTT	Unpedigreed pup
MUTT	Cur