Alastair Graham was looking after Bruno, a Staffordshire Bull Terrier cross, for a friend when he snapped after the animal bit his finger.
He tied the animal to a tree in Kirkcaldy's Dunniker Woods and initially attempted to slit its throat and stab it to death. But when he failed Graham went to a nearby petrol station and filled up a jerry can before pouring it over the terrified dog.
He then set the dog alight, causing horrific burns to the animal. A sheriff told Graham the attack was a "grotesque act of savagery".
But the Animal Health and Welfare Act that he was prosecuted under means Graham can only be jailed for a maximum of a year.
However, he will face "years" in jail after he also admitted an attempted knife robbery.
Fiscal depute Susan Dickson told Kirkcaldy Sheriff Court that a post-mortem on Bruno revealed he had still been alive when Graham had set him alight.
Graham, 23, a prisoner at HMP Perth, pleaded guilty on indictment to causing Bruno unnecessary suffering by causing his death in the fire on April 24 or 25.
He further admitted an attempted knife robbery committed alongside Steven Gourdie, committed on May 2 at High Street, Leven.
Larry Flynn, defending, said: "He has a vague recollection of doing this but was abusing alcohol."