What ya think? Should this officer have shoot the dog??

"This video is graphic"

California Police Officer Shoots Guy’s Dog Four Times in Front of Horrified Onlookers

What does everyone think about this? I'm of the belief that the officers need to defend themselves. I feel that it is the owners responsibility to secure his dog. The officers in the video just want to go home at the end of their day in one piece, which is fair. I am sure the officer would of rather not shoot the dog but in the moment I'm sure that he had a real concern for the safety of himself and the dog owner. 

The Hawthorne police department says: "It looks like the officer tried to reach down and grab the leash, and then the dog lunges in the direction of him and the other officers there," Hawthorne police Lt. Scott Swain said. "And I know it's the dog's master, and more than likely not going to attack him, (but) we've got a guy handcuffed that's kind of defenseless. We have a duty to defend him, too."