Absolute and totally no, it is not standard operating procedure to shoot a dog. This is stupid and out of control.
That individual should not be a police officer. Because dogs have a far more capable sense of smell, they are more reactive to mace, pepper spray and fire extinguisher spray. There are numerous ways to stop a dog without killing it. As a fire fighter, I can guarantee you, encountering dogs in emergency situations is very common, and in twenty-three years of dog encounters, I never had to seriously harm one.
The police were also totally negligent in not closing the door to the car, as they put themselves in danger by not taking a simple precaution that would have prevented any injury to them or the dog. Any rookie knows that the best way to secure a dog is to keep it in an enclosed area. These police officers were so incompetent that they were incompetently discharging fire arms BECAUSE they incompetently didn't secure an animal when they should have. It's also not like, "Oh, I forgot." They were warned by individuals to shut the door so the dog wouldn't get out. It was stupid, and not securing the dog SHOULD be a violation of Department Standard Operating Procedures.
The "officer" didn't close the door precisely because the "perp" asked him to. It's all about their testosterone-fueled control fetish, and they're not about to do anything that would indicate any humanity or empathy whatsoever to their "collared" "perps." That's why the "officer" killed the dog the second he could draw a bead on it - not because he felt "threatened," which is a pathetic excuse. In his mind, he was just killing some scumbag perp's dog. THAT is SOP, and if they'd been able to dig a single marijuana seed out of that car (and trust me, they tried their damnedest), we'd have never heard about any of this. You are NOT innocent-until-proven-guilty in the mind of ANY cop who stops you for ANY reason. This poor dog was doomed the second its owner asked the pigs to show any semblence of humanity.