Why Do Dogs Open Their Mouths When Playing

It’s a beautiful day at the dog park, and Rocky makes a friend of similar size. After they thoroughly sniff each other, they begin playing. They chase each other, dance in circles, jump on each other, and you notice almost the whole time they’re playing, their mouths are open. It looks like they’re biting each other. Both of you and the other dog owner are scared because you think the pups are about to rumble. But as you stand there, anxiously trying to decide when to step in, you realize that there is no harmful biting, bloodshed, or vicious attack. It’s the dogs playing. But why must they keep their mouths open to play fight and make you incredibly nervous?

When your dog plays with his mouth open, it’s called mouthing or jaw sparring. This is a healthy way for a dog to play with other dogs. Mouthing mimics an actual fight, but without the serious biting. This soft biting allows dogs to practice fighting without causing harm to each other. They will mouth at each other’s face and neck when fighting, sometimes while standing or on the ground. Mouthing is soft bites, but adult dogs have strong jaws, and these soft bites still apply some pressure. All dogs know this behavior and it’s normal for a dog to play fight with other dogs. Learning how to fight is an important part of survival for a dog and when puppies are young, they begin mouthing. The importance of dogs mouthing is that it does not escalate to aggressive biting and fighting. While all dogs mouth, there are some dog breeds that are more aggressive and of course larger than others, which could create a problem for a play fight. Have you ever punched your older brother lightly, but then he punched back so hard you became upset? And then you thought, “It is on!” This can happen with dogs. Your smaller or less aggressive dog can hold his own, but you don’t want either dog thinking this is a full-on brawl. That would only lead to damaging bites, bloodshed, and expensive trips to the vet. Some dogs that are more aggressive than others include American Bandooge, Bull Terrier, Dogo Argentino, Basenji, American Bulldog, Boxer, Doberman Pinschers, and Huskies. You’ll notice that these dogs are mostly larger dogs with lean muscle and traditionally were used to hunt or protect. They are still trainable and will want to please their masters, so don’t discount them as potential pets or buddies to another dog, but consider their size and temperament before bringing them home. Some dogs that get along well with other dogs include Bassett Hound, Goldendoodle, English Foxhound, Maltipoo, Vizsla, Pug, Bolognese, and Cocker Spaniel. These are dogs better in a multiple dog household. But like that fight with your older brother, a dog who is 15 pounds starting a playfight with a dog pushing 100 pounds could become problematic. Mouthing is natural for both dogs, but the pressure from a large dog with a bigger jaw might be too much for a little dog. 

Mouthing when playing is a normal, natural behavior and part of how a dog behaves. When the dog is a puppy, he learns how to fight by mimicking biting so he will be protected as he grows older. A dog who plays is getting out energy, socializing, and having fun, which are all things you want your dog to do. Signs that your dog is playing include play bows, where they stick their bums in the air and front paws on the ground and looks like they’re going to pounce. They are bouncy when they run, which indicates they’re happy. And sometimes they even look like they’re grinning as they fight. Other playful signs are when a dog lays down to fight. He is intentionally making himself less aggressive and giving the other dog the advantage. They will also switch roles, so the dog laying down will then become the playful “attacker.” The time to be concerned is when the playing escalates to fighting. Play mouthing is bites that are less painful than serious ones, but there are indicators that the dogs are upping their game. Signs that your dog is no longer playing and means business are if his body stiffens and becomes tense. He could wrinkle his muzzle, curl his lip back, and show his teeth. Aggressive bites are usually done faster and harder than a play bite. A dog who is serious will not bounce as they run, but rather sprint and chase with urgency. With dogs who know each other, this can happen when one dog does not read the signals from the other dog that he doesn’t want to play or should back down.

Watching your dog play fight and mouth can be nerve-wracking. You want your dog to have fun, but you don’t want him to become hurt. Stopping any dog fight, playful or not, is dangerous for humans, so a trip to a trainer is key. A trainer can tell you the signs to look out for, your dog’s behavior when a playful fight begins to escalate, and how you should intervene with the dogs if it ever becomes necessary. If you want to introduce a new dog into your household, ask your trainer about tips to make sure they get along. If you have a St. Bernard who loves to play and want to get him a friend to play with, a small dog like a miniature Yorkie would not be a good fit. A St. Bernard’s mouthing while playing might be too harsh for the Yorkie and could end up seriously hurting him. 

Watching your dog play and have fun can be fun for you too. Talk to your trainer so you can identify when your dog demonstrates any aggressive behavior and the play becomes a little ruff. Knowing the difference between playful mouthing or ruff aggressive will keep your dog safe and keep you relaxed as you watch.