Mayo Clinic, undertook efforts to lessen tensions between animal protection organizations and the scientific community, and to seek to identify areas of common agreement. Companion animals and shelters Service to local animal shelters, with a special focus on solving problems and challenges of importance to every one of the nation's humane societies, was an early priority for HSUS. Its first brochure, "They Preach Cruelty", focused on the tragedy of animal overpopulation. HSUS and its state branches operated animal shelters in Waterford, Virginia, Salt Lake City Utah, and Boulder, Colorado, and elsewhere, during the 1960s, and part of the 1970s. From the early 1960s onward, HSUS worked to promote the most humane methods possible for euthanasia of animals in shelters, using its Waterford, Virginia animal shelter as a model for best practices in this area. HSUS does not currently operate any Animal Shelters. Under Phyllis Wright, HSUS was a driving force behind the shift to use of sodium pentobarbital for animal euthanasia, in opposition to the use of gas chambers and decompression, the standard shelter killing methods until the early 1980s. In 1984, a General Accounting Office report confirmed HSUS allegations of major problems with puppy mills in the United States, setting the stage for proposed legislation to regulate mills in the 1990s. Exposure of cruelty in the dog trade In 1961, HSUS investigator Frank McMahon launched a probe of dog dealers around the country to generate support for a federal law to prevent cruelty to animals destined for use in laboratories. The five-year investigation into the multilayered trade in dogs paid off in February 1966 when Life published a photo-essay of a raid conducted on a Maryland dog dealer's premises by McMahon and the state police. The Life spread sparked outrage, and tens of thousands of Americans wrote to their congressional representatives, demanding action to protect animals and prevent pet theft. That summer the U.S. Congress approved the Laboratory Animal Welfare Act (later renamed the "Animal Welfare Act of 1966"), only the second major federal humane law passed since World War II. Goals and expansion Other broad goals during this time included a reduction in the U.S.'s homeless dog and cat population, the reform of inhumane euthanasia practices, and to regulate pet shops and to end the commercial pet breeding trade. HSUS and its state branches operated animal shelters in Waterford, Virginia, Salt Lake City Utah, and Boulder, Colorado, and