Sometimes humans don't respect cops and they feel like trying to assault them to get away. And that seldomly works out. When it's an animal that doesn't respect a cop, that's a whole different story.
A couple of cops drove their squad car out to a field in the middle of nowhere to retrieve a cow that had escaped from it's owner, but the cow had no intentions of going back to the farm peacefully. The cop that was trying to wrangle the cow had a cattle prod in hand, but the cow had other plans as it charged at the cop, nearly running him over. The cow did crash into the squad car though, probably doing some pretty significant damage.