In his first appearance in "Simpsons Roasting on an Open Fire", Homer was relying on a Christmas bonus to buy presents, but didn't get it. He was relying on this bonus because the jar of Christmas money that Marge accumulates for the family's Christmas treats was disposed of to pay for the removal of a tattoo that Bart got on his arm. Homer took the small amount of Christmas money he made working as a Santa at the Springfield Mall and bet it at the dog track. He had inside information on what dog was going to win, but instead bet on the "long shot," Santa's Little Helper, believing his name to be a sign. Santa's Little Helper finished last, and his frustrated owner abandoned him. Homer and Bart brought him home, and everyone was so happy with him that it was a merry Christmas after all.
In various episodes, Santa's Little Helper can be seen chewing on the newspaper and other objects in the Simpsons' household, tearing up the furniture, digging holes in the backyard and eating food from the living room table. During the second-season episode "Bart's Dog Gets an F", Homer and Marge are fed up with the dog's rambunctious ways and threaten to give away Santa's Little Helper unless he graduates from an obedience school. Santa's Little Helper's life with the Simpsons was not always easy: he nearly died of gastric torsion (referred to in the show as a "twisting of the stomach") during the third season because Homer initially couldn't afford $750 for the required operation, and he also broke two legs when Bart's tree house was demolished by Mr. Burns' oil well ("Who Shot Mr. Burns? (Part One)").
In the episode "The Canine Mutiny" during the 8th season, Santa's Little Helper was shortly abandoned by Bart for Laddie, a purebred and very well-trained dog he bought from a mail-order catalog together with various other expensive gifts and gadgets. To do that, Bart used a credit card he applied for under the name of his dog, yet the credit card company misread the form and issued a card to Mr. "Santos L. Halper". Laddie learned many tricks that Santa's Little Helper was completely unable to perform—most notably a back flip, CPR and using a toilet (however, in "The Seven-Beer Snitch", Santa's Little Helper demonstrates the ability to fly a plane). The Simpson family nearly forgot about their old pet, and Bart eventually gave him away instead of Laddie when repo men take back everything he fraudulently purchased. Feeling guilty about this disloyalty and bored with his too perfect new dog, Bart tried to get Santa's Little Helper back. When he finally found him, Santa's Little Helper was serving as a seeing-eye dog for a blind man named Mr. Mitchell, but eventually decided to return to his former owner, Bart.
In the episode "Stop, Or My Dog Will Shoot!", he becomes a great hero after he saves Homer in a cornfield maze, and then becomes enrolled as a police dog, teamed up with Officer Lou. Both Lou and Santa's Little Helper make a good team, foiling crimes together. After biting Bart's left leg (because he got angry when the court stated that he violated one of the police codes while catching Snake Jailbird), Santa's Little Helper is sent off by the Simpson family to live with Lou. Later on, once Springfield Elementary is in danger and Bart isn't able to escape, Santa's Little Helper comes in to save him, and goes back to living with the Simpsons.