We have a boxer-rottweiler mix (tail also docked), she weighs about 70 lbs. Of course, being a boxer and a rottweiler, she has a solid woof, is very muscular, and she loves to greet people. She has been known to knock some kids over (not intentionally), and alligator-snap in their direction if they poke where she doesn't want to be poked. She is another that won't put teeth on skin.

She knows kids are units to be protected, but isn't quite sure about how to interact with them, especially the smaller ones (the same ones she can knock over). We've used kids of friends as training for her, to teach her that kids are units that she needs to respond to, not just be aware of, and to try to reduce her jealousy of the attention that kids get. She also has a herding instinct that we have to try to turn off - sometimes if we're playing a chase game (like tag) with a kid, she'll start trying to herd the kid, nipping at their heels or clothes (never skin, but I'm sure to a parent it just looks like scary rottweiler/boxer eating my precious child). It doesn't matter how much exercise she gets, something turns it on and you have to be the one to turn it off. I think with a lot more practice, we could work it out and she'd learn that children are not to be herded in that way. :P

I think some kids end up at the dog park because, well, they love dogs. But, dogs are a two way street, and it's important for kids to learn how to deal with dogs as well. Maybe teach your dog to respond to a command that you can also teach the kids, and turn it into a learning exercise (rather than something negative). That would also give you something you could use to call him off if you think it's getting ahead of what the kid can handle. Or, if you can teach him to look to you before he sets off, you can give him the "okay" to run if you're confident (or confirm) the kid can handle it.

I looked up the rules for our dog park and I think they could use a section on human responsibilities, too. There's some general stuff, like "remain in control" and "kids under 16 must have a parent present," but not really enough on "how to be a responsible dog park user."

As an aside, that (loosely) reminds me of a sign at Cat Tales, a wild cat park that says: "Don't Run, You Look Like Food." http://picasaweb.google.com/lh/photo...SEC1UXNu3mmuwA

Good on you for the long walks and staying attentive to him at the dog park, though. I do see a lot of humans doing the "hang around and chat while your dog misbehaves". My dog seems to want to smell everything and follow me more than play, so I haven't actually had to deal with a lot of dog park interaction.