Dog parks are a wonderful theory.

Who could object to a safe place to run your pup that gives him a chance to explore his inner pack hound?

Olivia and I visit the Lower Allen Township Park in Mechanicsburg almost every weekend. She plays in the size-appropriate small dog area that is fairly well-maintained and the township maintains a nice trail network along the scenic Yellow Breeches Creek for dog walkers.

But a dog park can turn into the worst, most hazardous playground in a heartbeat, a dirty place where bullies rule. One traumatic experience can lead to injury or a lifetime of fear aggression.

I have friends with big dogs who no longer go to Lower Allen because their laid back dogs were terrorized by a mean dogs, some of them unneutered. I've seen some people bring aggressive rescue dogs to the dog park to "socialize" them. I questioned one young couple about whether their ten-week-old puppy was properly vaccinated.

There is a list of rules posted prominently at the yard entrance - and a stated requirement that users register their dogs showing license and vaccination records - but it's clear not everyone obeys them.

Mother Jones News posted a very helpful piece on its website recently titled: "15 things humans do wrong at dog parks."

Number 1? Not picking up after your dog. Seems obvious (and easy when a dog park offers you free doggie doo bags), but surprisingly there are scofflaws on that front.

The article goes on to describe other dog park dangers like bringing in an unspayed or pregnant dog, not recognizing signs that precipitate a fight, bringing an unvaccinated (or partially vaccinated) puppy and burying your face in your smart phone or chatting with fellow pet owners while ignoring your dog.

So next time you head out to the dog park remember to watch your dog and mind the poo.