Santa's Little Helper's original owner was the man who had Santa's Little Helper running at the Springfield Downs Dog track. After Santa's Little Helper lost on Christmas Eve he abandoned him in the parking lot and Homer and Bart took him in.
After Santa's Little Helper became the face of Duff Beer, his old owner came back and claimed him again to get the money the dog was getting. Eventually, when a new face for Duff Beer was found, he let the Simpsons have him again due to him being worth no money any more.
