While McMahon was best known for his investigations of dog dealers, research laboratories, and the transportation of animals, he also inspected hundreds of rodeos, slaughterhouses, stockyards, cockfights, dogfights, horse shows, and animal auctions. In the late 1960s, McMahon extended his work to include wildlife protection, providing relief to wild horse populations in the western United States and launching an investigation of the Pribilof Island seal clubbing.
Unti, Bernard, "Frank McMahon: The Investigator Who Took a Bite Out of Animal Lab Suppliers" (2013). Animal Abuse, Animal Welfare, and Animal Protection. Paper 22.