In February 1966, LIFE published an article and a series of shocking photos that generated a huge outpouring of letters from the magazine's readers. Many of the letters were among the most passionate that the long-lived weekly ever received. The subject of the article? Not the war in Vietnam. Not an attack on Civil Rights marchers by police. Not another frightening escalation of the already-frigid Cold War.
This time, the outrage was in response to an article on dogs. Or, more accurately, an article on the inhumane — indeed, the horrifying — treatment of dogs by men and women who, as LIFE put it, were "taking advantage of the growing demand for dogs for vital medical research" and, in the process, were cashing in on a "lucrative and unsavory business" built and maintained on the misery of man's best friend.
Titled "Concentration Camps for Dogs," and featuring unforgettable pictures by LIFE's Stan Wayman, the eight-page exposé cast a cold light on a shadowy — but, at the time, legal — business in which "dealers rove the country paying a buck or two to anyone who comes forward with a dog, and no questions asked."
Family pets, trained to obedience and easy to handle, are especially prized, and the Humane Society of the U.S. estimates that 50 percent of all missing pets have been stolen by "dognappers," who in turn sell them to the dealers. Some dealers keep big inventories of dogs in unspeakably filthy compounds. . . . Many so not sell directly to labs but simply dispose of their packs at auction where the going rate is 30 cents a pound. Puppies, often drenched in their own vomit, sell for 10 cents apiece. Stirred by revelations to a House subcommittee of such outrages and prodded by the continuing raids on these camps by humane societies, Congress already has eight bills pending, any of which would outlaw these shameful conditions.
In the summer of 1966, Congress passed the Laboratory Animal Welfare Act. President Johnson signed it into law on Aug. 24 of that year.
A quarter-century later, however, when LIFE was publishing as a monthly, the magazine ran another, equally appalling feature on "puppy mills" operating in the U.S. -- this time with pictures by the Pulitzer Prize-winning photojournalist J. Ross Baughman. (Read about that story and others that Baughman shot in the course of his extraordinary career in his new memoir, Angle, published by VisionsPress.)
Humanity's ruthlessness in the pursuit of money is, evidently, something that has always been — and perhaps always will be — with us. But here, on the 60th anniversary of the Nov. 22, 1954, founding of the Humane Society of the United States (motto: "Celebrating Animals, Confronting Cruelty"), LIFE.com recalls that 1966 article — and republishes Wayman's photographs — in tribute to those who battle barbarity in all its forms.
Liz Ronk, who edited this gallery, is the Photo Editor for LIFE.com. Follow her on Twitter at @LizabethRonk.