I have several dog parks near me, some are fenced in and some are not...some have lakes for the pooches to swim in and some are more wooded. My aussie mix, Graham has never had a major problem with any of the dogs but my pug, Cassie was attacked by a yellow lab who was very possessive of tennis balls. Cassie had facial trauma, had a couple teeth knocked out, and she had to have strict cage rest for 3 full days because of a nose bleed. I still take the dogs to the dog park but I am so careful when I go, and I only take Cassie when the crouds of dogs are smaller. As nervous as I am at the dog park, it's a good thing for the dogs (usually) as the dogs get to just let loose and be dogs.