I have observed dogs "caretaking" small children (way too small to be by themselves!) playing in the ocean on more than one occasion. Better parents than their parents.... Totally taken for granted. Kinda heart breaking.
Like Amanda, I have seen a handful of dogs that are too aggressive / vicious to be allowed to roam around freely and chase golf carts and bikes. Some of them pit bull mixes. It is just remarkable that more children have not been hurt. I always carry rocks in my golf cart / empty beer bottles just in case.... and had to use them yesterday in fact.