LOXAHATCHEE GROVES, Fla.—A dozen tan-black-and-white beagles romp and sniff inquisitively, tails wagging, paws padding over pristine artificial turf, noses exploring every inch of a shade-covered play yard.
Before May, these dogs and nearly 2,200 like them knew only the inside of stacked metal cages at a Wisconsin facility producing puppies for research labs.
The beagles—a breed developed for hunting and known as gentle, loyal pets—never experie…