Playground bullies
Although dogs are social animals and regularly engage in various forms of play, the artificial setup of a dog park can be challenging. Many people bring their dogs to the park to burn off excess energy, but these dogs often display over-aroused and rude behavior that can trigger issues between dogs. Dr. Heather B. Loenser, senior veterinary officer of the American Animal Hospital Association cautioned that “unfortunately, just because an owner thinks their dog plays well with others, doesn’t mean they always do.”

Having your dog in a dog park requires trusting that everyone in the park is monitoring their dog, and is a good judge about whether their dog should be in the park in the first place. That’s a lot of trust to put in a stranger.

Unlike doggy day cares or play groups, most dog parks are public spaces that are not screened or supervised by canine professionals.

This can be an issue with fights between dogs that can lead to dogs learning inappropriate behaviors from other dogs. “Bad experiences can also ripple outward and cause our dogs to have issues or concerns outside of the dog park as well,” Mr. Hof said, adding that dogs at dog parks might pick up bad habits such as being pushy when greeting or engaging in play with other dogs. On other hand, dogs that are overwhelmed by the boisterousness of others may become withdrawn, skittish and nervous when meeting other dogs in and out of the dog park.

Injuries
One of the biggest dangers of dog parks is that they often don’t have separate play enclosures for large and small dogs, or when they do, owners can choose to disregard those spaces. Even without meaning to, a large dog can easily cause serious injury or even kill a smaller dog.

From minor scuffles to serious incidents, injuries are common at dog parks. Bite wounds are common, even from rough play. Even if the wound seems small, “seek veterinary care immediately,” Dr. Loenser advised.

Bites that occur in fights or during play often involve tearing under the skin, which can be complicated to heal, and may carry a greater risk of infection. Muscle strains and sprains from lunging and rough play are also common. “Anytime dogs quickly pivot on their back legs, they are also at risk for tearing the ligaments, specifically the cranial cruciate ligament in their knees,” Dr. Loenser said. These types of knee-and-ligament injuries often require expensive surgery and extensive healing and rehabilitation.

Diseases
Even clean and well maintained dog parks can pose health risks, in particular the spread of easily communicable diseases. One challenge of dog parks being unregulated public spaces is that while most post signs saying dogs should be vaccinated, no proof of vaccinations is actually required.

The American Animal Hospital Association advises owners who bring their pets to the park to have them vaccinated with the Bordetella vaccine, which prevents “kennel cough,” as well as distemper. You’ll also want to have your dog vaccinated against leptospirosis, as communal water bowls, puddles and other water features in dog parks can carry leptospira bacteria. All dogs should be vaccinated against rabies, and dogs that visit dog parks should be on flea and tick prevention as well as year-round heartworm prevention. Dogs that visit dog parks should also be vaccinated against canine influenza (dog flu) that can be transmitted through the air.

Dr. Loenser cautioned that although “currently, the influenza vaccines available cover for the strains that are most commonly seen, if new strains are introduced or mutate, these vaccines might not provide cross-protection.” If that were to occur, dogs that visited dog parks and had contact with a large number of dogs that might or might not be fully vaccinated would be at risk of getting sick.

Body language
Most dog owners aren’t skilled at reading their dog’s body language beyond a wagging tail, so warning signs that your dog is uncomfortable, unhappy or angry are often ignored. This leads to minor and major dog fights. Understanding canine body language is key to supporting your dog’s comfort and safety, and assessing if a playgroup at the dog park is going to be a good match.

“The dog park is not a place for you to let your dog run unsupervised while you socialize with other people,” Mr. Hof said. “Keep an eye on your dog and make sure that they are both being good and having a good time.” This means watching the actions and behaviors of your dog and the other dogs in the park. If things are getting too intense, that’s a good time to leave.

But what exactly should you be watching for? Dr. Loenser says that subtle signs of fear or aggression include “lip licking, yawning or panting when not hot.” Other signs of discomfort or a brewing issue include stiff bodies and erect tails. Keeping an eye out for these signs can give you the edge to intervene on your dog’s behalf before an interaction with another dog escalates.

Even dogs that appear to be playing well together may be at risk. “Healthy play between dogs should include small breaks or pauses,” Mr. Hof said. “If you are uncertain about if all dogs are happy, I recommend stopping the dog who may be too over-the-top and seeing what the other dog does. If the other dog tries to re-engage, it’s a good indicator that everything was okay. If the other dog runs off though, a break was a good idea.”

Any kind of behavior that involve one dog pinning another dog is also one to avoid. Barking, growling and other vocalization occasionally during play is normal, but frenzied barking is generally too much.