Teddy was never meant to have a name. He was born a number, just one of tens of thousands of dogs—mostly beagles like him, chosen for their trusting, docile nature and compact size—bred in the United States for use in experiments each year. Teddy was meant to live and die in a laboratory, without...

In 1966, amid a growing clamor from the American public and Congress to do something about the shady business of family pets being stolen and sold to research facilities, U.S. President Lyndon B. Johnson signed the Laboratory Animal Welfare Act into law. Amended several times over the years, the...