The St. Petersburg Times in Florida reports that Gus, a Chinese crested dog, had cancer. He was 9.
Gus was rescued from a bad home and went on to win the annual World's Ugliest Dog contest at the Sonoma-Marin Fair in northern California.
Gus came from humble origins. According to the fair, his adopted family in Gulfport, Fla., rescued him after learning he was being kept in a crate inside someone's garage.
He had one leg amputated because of a skin tumor and lost an eye in a cat fight.
Gus' owner had said the prize money from the contest would be put toward the dog's radiation treatment.