Tbf the pitbull and owner were not at fault in this case. Since they threw a mud ball at it
Laws are set up to protect citizens over property and pets. And so, the dog does not have self defense rights.
Most places have a leash law to protect citizens. The dog was not on a leash and owner was no where to be seen. So either it escaped an enclosure, unbeknownst to the owner, and ran into the park or the owner let it roam free, and out of sight, in the park. The dog attacked a person, and nearly killed them.
This is very serious and an example of gross negligence. Typically the dog would receive an order to be muzzled in public, if not put down had it survived. The owner would receive a fine and be sued for damages. Had she died, he would have been charged with Involuntary manslaughter.