One year when I was elk hunting in Colorado I saw a field that contained cattle and 1 horse. The cows had "COW" painted on both sides. The horse had " HORSE", though I don't think it was your donkey.
That same year someone shot a horse that had a rider on its back during a guided elk hunt (must have been bad eyesight).
As to the Police armament I think cities across the country used their Govt. Homeland security money to re-outfit with the latest stuff.
I don't know if it will ever be turned on the average citizens but there may be hope in the opposite direction.
I read a while back that in ancient Rome during one of their many civil unrest with rioting,
the Emperor unleashed his "Pretorian Guard". This group was "The Army", the only army
allowed by law in the ciy of Rome ( 10, 000 strong)
The "Urban Cohorts" which were the police force (1,500 strong) trained and outfitted as the army was, joined the people against the Pretorians.
We can only hope that in a similar situation the Sheriffs (elected) and Police Chiefs (appointed) will uphold the Constitution.