Role-playing game handle: Horse de combat
While the illegal sports of dogfighting and cockfighting are better known, the blood sport of horsefighting is also practiced in some parts of the Far East, despite a fair amount of outcry.
Combat by proxy is not limited to vertebrate species. There are enthusiasts of fighting crickets in China
Perhaps one could redirect this interest to virtual depictions of blood sports in the context of video games, so that actual animals would not suffer. There is already a series of Alien vs. Predator games which one could consider to be a variation on this idea, albeit one that is a little easier to market.