Can dogs smile? Here's what your pet is trying to tell you with that sweet smirk.

Coming home to my dog after a long day can sometimes make all the difference. Waiting for us all day, she wags her tail in excitement and showers us with puppy "kisses" as a sign of affection.

The cutest of all? When we offer up a big, goofy grin, she matches us with a smile of her own.

But are our dogs really "smiling" the way humans do? We asked a veterinarian about what our canine friends are trying to communicate.

Do dogs smile?

Yes! While any dog can smile, some breeds are genetically predisposed to do it more than others, according to veterinary behavior specialist Dr. Lore Haug. These breeds include Doberman Pinschers, terriers and cattle dogs, to name a few.

“It is essentially an appeasement greeting behavior that seems to be directed only at people,” Haug says. “Dogs don’t do this true smiling behavior to other dogs.”

Dogs smile by pulling one or both lips back and may show all or some teeth. The "smiling" is often accompanied by other greeting behaviors, like approaching, wagging or even whining.

Smiling is a form of “active submission,” Haug says, while other submissive signs include behavior like curling their body down or rolling on their side.

Why do dogs smile when they’re in trouble?

Dogs may also smile when they’re feeling guilty, or when you’re trying to get them to do something they don’t want to do, like take a bath.

If they give you a submissive grin when they’ve done something wrong, it’s because they want to avoid getting in trouble with their owners, Haug says.

Is it normal for dogs to smile with teeth?

Yes, it’s normal for dogs to bare their teeth when they smile. The bigger problem is that people often misinterpret a toothy smile as aggression and become scared, Haug says.

“They may respond in kind and actually show kind of confrontational behavior back to the dog or punish the dog thinking the dog’s growling at them,” Haug says. “If they do that, they may very well end up actually creating a defensive aggressive response in those dogs.”

It’s important to know the difference between a toothy grin and a dog on edge. Smiley dogs usually wag their tales in a wide sweeping or circular motion and will approach you or curl their body as they walk toward you. They usually won’t growl, though Haug says on rare occasions she’s met dogs that accompany their smile with a “wheezy kind of grumbling noise."

“If the dog’s threatening you, their body might be stiff and they might be moving really slowly and look tense,” Haug says. “Whereas a smiling dog isn't going to look like that, they're going to be loosey-goosey and wiggly.”

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This article originally appeared on USA TODAY: Do dogs smile? Here's why your pup is baring their teeth.