A dog is a wild mammalian quadruped that is usually domesticated by humans to keep as pets. Dogs can range from being very friendly to vicious, depending on the type of dog, its upbringing, and owner(s).
In mainstream Smurfs media, Puppy is the dog that the Smurfs keep as a pet, which was given unto them by his former master Homnibus, starting in Season 5.
In "The Sorcery of Maltrochu" comic and cartoon adaptation, a young knight named Sir Thierry is turned into a small hound dog to prevent him from marrying Lady Genevieve. While helping him return to normal, Peewit is turned into a bull dog by the same magic powder used by Baron Maltrochu, but both are made human again by the time of the wedding ceremony.
In the season 1 episode "Sideshow Smurfs", there is a dog called Bluster, whose master is Bombast. He was once the highlight of Bombast's show. After Bombast captured Smurfette and Clumsy to be the new performers, Bluster is lured into helping Clumsy and Smurfette escape from their cage in Bombast's wagon, but they don't get far in their escape when they wound up in Bombast's nail sack and were returned only to be captured again. Later, after Gargamel spot the Smurfs and wants to get them, he stopped Gargamel from stealing the Smurfs. Finally, as Gargamel ruined Bombast's show, both he and Bombast chased Gargamel and Azrael to punish them.
In the live-action The Smurfs film series, the Winslow family owned a basset hound named Elway that originally saw the Smurfs as a threat when they entered the apartment to search for Clumsy in New York City.