Or lock them in a small cell with a Great Dane named Bubba.
I hate to tell you this, but the great dane would not live. The toughest dogs in the world in a pit fight are smallish pit bulls...40 to 50 lbs. Nothing beats them.
I'm afraid those two pits would be picking their teeth with the Dane's bones when you checked on them the next morning.
Here's the cell-mate you want for the pits. He's bigger, faster and stronger in every way. He would just about swallow them whole.
Or a giant, mean Clydesdale name “Big Bud.”
I have an Akita that would make short work of a pit bull.