(Salem, OR)  --  Salem police say they've arrested a man who choked a K-9 into unconsciousness.  Authorities say Justin Lazo was encountered Saturday by officers who responded to a report of a man displaying unusual behavior in the area of 15th and Wilbur in Salem.  Officials say Lazo grabbed the dog, named Duke, by the collar and choked him, and officers used a Taser and pepper spray to subdue the suspect.  Police say Lazo's finger got caught in the dog's collar and later had to be amputated.  Duke was back on patrol yesterday.