Dog the Bounty Hunter squared off with an old opponent in Las Vegas and when fists started flying cops had to get involved.
Dog was at Luxor in Vegas Wednesday for a bail bonds conference when he ran into an insurance broker named Ronnie Frank, who's had beef with Dog in the past.
A rep for Dog says Frank got in a threatening stance and said, "I'm gonna kill you, you long-haired mother f*****." Dog's security guard tried to break it up by putting a hand on Ronnie's chest.
We're told Ronnie slapped his hand away, and that's when Dog's guard punched Ronnie in the face. Hotel security called Vegas cops, who cited Dog's guy for battery.
On a positive note for Dog -- Beth was voted President of the Bail Bonds Association later that day.