I was involved in an incident at our local dog park last year, and while my own dogs were not involved, I ended up with broken skin on my wrist and hand, as I reached in to stop a mastiff puppy from killing a poodle puppy (yes, I know, I should not have jumped in the middle, but… it’s hard not to intervene and help out in a scary situation like that!) The poodle owner’s dad kept angrily insisting that the mastiff owner pay for the pup’s surgery, and (to try to defuse the situation) I called my trainer for her opinion. She has a lot of experience with this kind of thing, and she said: “Dog owners enter a dog park at their own risk. If their dog is injured, they are legally obligated to care for their injured dog. If the other party (the owner of the dog that inflicted damage) offers to pay, that’s great! But there is no legal obligation.”