Breaking off cows

Have him very well started on hogs before you break him off cattle. Any dog that's straight catch on cattle will be the same on hogs. It has been my experience that a hard dog like you describe needs a slow change to hogs. Get him started on hogs and then just show him some cattle from the truck, don't turn him lose, and use as little shock as you need to send the message. They take him directly to some hogs and let him work. Repeat his many times until he has lost his drive for cattle.

A hard dog like this can be ruined very easily. Your focus is very important when breaking him. Focus intently on the hogs when working, Do NOT focus on the cattle when breaking. A stock bred dog will engage what the handler focuses on. He will read you like a lead dog. Use that to your advantage.

There should be emotion and no ego in the breaking process. And you might not get it done, if not send him to a cow catcher who would value the dog just as he is.