This is not legal in most places but theres talks of other animals fighting so why not ask.
I know it is popular with Bitcoin and gamblings.
In my country it is legal to bet on animals fighting but I don't think people really do bet on a dog fight here. I have watched competitions on dog fights but it is not something I really will like to bet on as I see it as animal cruelty! Some people may see it otherwise but I do pity animals especially when human beings are taking advantage of them.
Cruelty while watching how the two fighting dogs will try to save once lives not sure if how that can be an entertaining things to watch, might be just because of money that can be gamble so there's still people who manage to bets and enjoy the winning that they've got after the fights, its between the owners and those who wanted to gamble their money and pets.