Even though Roscoe Arbuckle is listed as star, and the lovely Minta Durfee is billed second, Al St. John shines more brightly, but even he is overshadowed by Luke the Dog as "Fido."
Al and Roscoe are both tremendously gifted acrobatic actors, especially St. John, who carried his talent into countless roles during the coming years, especially into B Westerns.
Al "Fuzzy" St. John stole movie after movie from the likes of Buster Crabbe and Al "Lash" LaRue.
He was, in fact, one of the best cowboys on the silver screen.
Roscoe, known as "Fatty," didn't do so well, but became an admired director after a fatality incident ruined his reputation.
His own athleticism really made his role in this relatively minor short quite impressive. The story was slight, but the performers gave us LOTS of action, including fights galore.
"Fatty's Faithful Fido" is a charming knockabout that I do recommend your seeing, at least once.