HE THREATENED TO DROWN MY DOG! I'M A RETIRED K9 OFFICER. HE PICKED THE WRONG FIGHT! The terrier's frantic barks echoed across the desolate park, each yelp a desperate plea against the biting wind whipping off the river. I was fifty feet away, enjoying an early morning walk with Gunner, my German Shepherd, when I saw it. The man. The dog. The threat. My blood ran cold. A bulky figure, face contorted with rage, had the small dog dangling by the scruff of its neck. "Shut your yap, mutt!" he roared,