Ruling against thoroughbred breeders and trainers, an administrative law judge backed up a decision by Florida gambling regulators to allow Calder Race Course to keep its lucrative slot-machine license after demolishing the grandstand where bettors once watched horses compete.

The case, filed by the Florida Horsemen’s Benevolent and Protective Association against the state Division of Pari-Mutuel Wagering, highlights the growing tension between the greyhound and horse industries and racetrack operators, who have sought to do away with live racing while keeping more-profitable gambling activities such as slots and poker, a process known as “decoupling.”