Here’s some more information. I was going to exhibit some information about a common house plant that can be used to silence animals but will pass on that and present the following.
Dog Silencer Pro™
http://www.ultimatebarkcontrol.com/ds_pro.htm
The point is that if any of us escalate fear and violence illegally in our locales, things can get more complicated all around us. Imagine guard dogs no longer barking and a criminal approaching with a crossbow and/or other quiet weapon. There are many legal and honorable ways to defend or properly apprehend and no long-term benefit to becoming a bad boy (or girl). Barking dogs will deter creeps as well as a dangerous animal will.
Police dogs are best used for finding explosives, evidence, etc.
For citizens more interested in defending their own properties, there’s no sense in keeping liability weapons that are as dangerous to yourselves as to neighbors or visitors who need help (victims of transportation breakdowns, crimes, accidents, etc.). Imagine someone coming to your door late at night, after their transportation breaks down. The best way to deal with an assault (home invasion) is to be able to see visitors coming (barking, non-lethal dog, cameras, etc.) and to deal with any threats yourself.
You can discern between friendlies and foes better than a dangerous animal, and there are many ways to defend yourself. It is even better to avoid criminal invasions altogether by having your place built to deter criminals and to direct visitors through particular routes. There are even more ways to do that. A home can look very inviting to good visitors while looking like (and being) a nightmare to would-be burglars and home invaders.
As a reliable method of dealing with out of control police dogs, I suggest an Irish Wolfhound.
A wolfhound was at a county fair, laying on the grass with the child of the family when some German Shepherd K-9 dogs were walked past by their officer handlers.
One of the K-9 dogs snarled at the wolfie. Wolfie then assumed their existence was a threat to the child and went from warm, furry, ambulatory rug to “Kill the Bad Wolves” mode. Before anyone could react, three dogs were down and dying, and the 4th had to be euthanized.
Fortunately, the officers were wise enough not to try to shoot.
Then, the wolfie went back over to the child.
Problem solved.
Turns out there was a reason such dogs were so highly valued in antiquity.