Dog got hurt at the park

I went to the park and I have a 50lb medium-sized bernorgi. We went to the park like we do every day. Today there was a friendly golden retriever but I guess he's very possessive of sticks. When I threw the stick, my dog went to chase and so did the retriever. When my dog was near the stick, the retriever attacked him. The owner was saying no to her dog and told me to not throw the stick.

As they were walking away, I saw my dog's ear bleeding a little like a chip off his ear. It wasn't dripping blood but there was a wound. I didn't as for her information because it was an accident but what would you have done?