SF Chronicle:

If Charlie can be put in a sanctuary for troubled dogs, that would be fine. But he's a dangerous dog. That's not one opinion, it is several. He viciously attacked a Park Service horse on Crissy Field on Aug. 6. He slashed the horse on the flank and latched onto a leg. When the horse threw his rider and broke free, Charlie chased him for a mile and a half and was frightened off only when a motorcycle patrolman cut him off and blasted an air horn. Taking the injuries into account and the persistence of the attacks, a Police Department review determined that Charlie was vicious and dangerous and should be put down. Gizzarelli protested, and an evaluation was held with the eminent veterinarian a month later. That evaluation seconded the diagnosis of a dangerous dog with predatory instincts.

But there's no such thing as a bad pit bull. Only bad owners badly trained police horses:

The owner of a pit bull named Charlie who is facing a state-court euthanasia order after reportedly chasing a police horse a mile and a half in a San Francisco park last year has filed suit in federal court to get a restraining order.... An independent veterinary behaviorist reportedly has found the dog to have a severe predatory behavior issue. However, many observers have rallied to support Charlie, arguing that the police horse wasn't properly trained to deal with dogs.

I propose that SF train its police horses not to run from pit bulls that have slashed their flanks and are chewing on their legs—that could trigger a pit bull's predatory instincts—but to turn and stomp to the fucking dog to death.