Just emulate what officials in Weymouth, Dorset did to a family's companion dog.
Step 1: Wait for burglars to break in and enter, leaving the door open and allowing the super-vicious-did-not-bite-the burglars-dog to wander out.
Step 2: Wait for frantic calls from the public claiming a large dog is running around and maybe panting or baring teeth or just, you know, taking a jog.
Step 3: Rush to the scene and use a noose pole to capture the dog who is so vicious, he needs to be dragged along the pavement to a van.
Step 4: Kill the dog two hours after capture.
Step 5: Blame the dog and the guardians after the fact by presenting evidence that the dog had to sometimes be muzzled at the vet and CLEARLY, after killing him, this made killing him okay!
Step 6: Claim that a confined dog poses a threat to the public after sort of apologizing but not really (because that would require admitting you're a stupid asshat): " 'We wish to express our regret for the undoubted hurt felt by the family, but in this case we had a wider duty to protect the public.'
Does Dorset not have an animal shelter? Is the public deeply threatened by a dog safely confined at a veterinary office? Oh wait, sorry, I'm trying to act like killing the family dog is okay. Sorry, Dorset officials, carry on!