Oh, behave!

(From "Dog Parks and Basic Bark Park Etiquette" at about.dogs.com)
Off-leash dog parks are a wonderful recreational outlet for dogs and people. The opportunity to run and play with other dogs in a securely fenced environment is a valuable tool in a pet's social development. Unfortunately, not every dog park is filled with responsible owners, and not all dogs are socialized enough to handle the excitement of a dog park. Help make your local dog park venue more successful and less stressful by following this basic etiquette for bark parks.

Immunized Dogs Only: Don't bring your unvaccinated dog or puppy in a park full of other dogs. It's just asking for the rapid spread of disease, some that could be fatal, especially to young puppies. Most parks will prohibit the entry of puppies younger than four months, the common age when the full range of puppy vaccines have been given.

Bring a Healthy Dog: Just like with people, sick dogs should stay home until they're well.  It's just common sense. Why would you want to expose other pets to suffering from kennel cough, fleas, mange, or other health problems?

Be Responsible For Your Dog's Behavior: The best way to be a responsible owner is simply pay attention to what your dog is doing. If your dog digs a hole, fill it back in, and so forth. Be aware of other people's reaction to interactions with your dog - not everyone can handle being tackled by your lovable ball of energy. And if your dog can not play nicely with other dogs on that day, then take him/her home. Be familiar with dog body language so you can recognize the difference between play and aggression in your own and other dogs. Please note: some dogs may be unpredictable or aggressive to the point that they are not ready to be at an off-leash dog park. If this is the case for your pet, you should find another outlet for their exercise to avoid dangerous situations.

Clean Up After Your Dog: To further prevent the unintentional spreading of disease and intestinal parasites, pick up after your dog. Besides, leaving piles for other dog owners to clean up is simply lazy and rude, and could result in you being fined or you and your dog being banned from the park. Persistent problems can also lead to the dog park itself being shut-down.

Human Children at Off-Leash Dog Parks = Danger? There are many good reasons to keep children out of off-leash dog parks. The possibilities for accidents are staggering - not all dogs are predictable around little humans, and vice versa. 

Keep Female Dogs in Heat at Home: Taking a female dog in heat out in public is irresponsible, especially out somewhere where there are dozens of dogs running loose (with possibly unneutered males). You're just asking to pay for vet bills for your and other dogs.

Don't Bring Too Many Dogs: Many parks will have a posted limit on the amount of dogs one person can bring into a dog park. It's really best not to bring more than you can handle, even if that number is less than allowable limit.

Only Bring Dogs: For the safety of all concerned (dogs, the other animal, and the people in the park) do not bring animals other than dogs to a dog park.
 
Follow The Posted Rules: Following each park's individually posted rules and regulations will help keep dog parks open and available to all dogs. Failure to obey the rules can result in your local park being shut down, or worse, cause a serious accident that could have been prevented.