Calling All Curs (1939)

The stooges run a pet hospital and get an important patient, Garcon, a rich ladies poodle. When dognappers posing as reporters steal the poodle, the boys are in a tough spot. First they try to fool their client by disguising a mutt as the poodle. When that doesn't work, they use the mutt as a bloodhound to track down the crooks. When they discover the bad guys hideout, Curly defeats them in a fight and they find Garcon, only to discover that "he" has had a litter of puppies.