My dog is a big yawner. The very first time I picked him up when he was a puppy, he was a yawning, bundle of squirm. (You can see his photo from his those yawny puppy years below.) It's two years later, and he's still a vocal yawner. He yawns when he plays, when we're training and when he's sleepy.

brodie puppy yawningCanine behaviorists say there are several reasons our canine best friends open their jowls so wide. Yes, they could just be tired, but oftentimes there's something deeper going on.

Like us, dogs sometimes just yawn when they're drowsy. If your dog yawns when he's stretching and just getting up from a nap, or when he's curling up in his bed for the night, there's a good chance your pet is just sleepy, say trainers. If his body language is relaxed (and better yet, if he falls asleep not long after) you know that's the reason behind his wide-open gape.

Calming signals

Like licking his nose or turning away, a yawn is a calming signals that dogs give other dogs and people, says Norwegian dog trainer Turid Rugaas, an expert on canine body language. Like wolves and other species that live in packs, dogs have to be able to communicate and cooperate in order to avoid conflict and live in harmony together, she says. They use these signals on each other and on themselves.

Rugaas says dogs have 30 or more calming signals that appear to be ingrained. That explains why even young puppies use these signals — like yawning — when they're first picked up and handled.

Rugaas writes:

"The dog may yawn when someone bends over him, when you sound angry, when there´s yelling and quarreling in the family, when the dog is at the vet´s office, when someone is walking directly at the dog, when the dog is excited with happiness and anticipation — for instance by the door when you are about to go for a walk, when you ask the dog to do something he doesn't feel like doing, when your training sessions are too long and the dog gets tired, when you have said NO for doing something you disapprove of, and in many other situations."

In most of these situations, the dog is stressed or nervous. He's trying to send signals to the other members of his "pack" that he's not a threat, asking them to back down. Or he is just anxious, scared or excited and is trying to calm himself.

That explains the dog that gets so worked up when he's playing that he yawns — to calm himself down but maybe also to signal to his playmate that he's just having fun and he's not a threat. And the same idea surrounds the pet who gets so pumped up about going for a walk or a car ride that he yawns over and over as he waits for the leash to be clipped to his collar.

Training can be stressful

dog obedience class Dogs will often yawn during obedience class if they are stressed. (Photo: SpeedKingz/Shutterstock)

Want to see a lot of yawning dogs? Check out obedience classes. There, canine participants aren't yawning because they're bored; they're yawning because of stress, says Stanley Coren, Ph.D., author of several books including "How to Speak Dog," writing in Psychology Today.

Coren says dogs can get frustrated when new dog owners use harsh, threatening language when training their dogs to sit and stay.

"Such a tone of voice implicitly suggests that the dog just might die if he moves from his place. For this reason in a beginner’s class you will see a number of dogs left in a sit-stay position, yawning, while their masters stand across the room staring at them. When the owner is taught to use a more friendly tone of voice for commands, the yawning behavior usually disappears. In this sense, yawning might best be interpreted as 'I'm tense, anxious or edgy right now.'"

In addition to relaxing your tone, you should take frequent breaks and make training fun, experts advise.

What about contagious yawns?

What does it mean when your dog yawns after you yawn? It could be because he empathizes with you, says a recent study. The study, by researchers at Portugal's University of Porto, found that dogs yawned even when they just heard the sound of yawning.

"These results suggest that dogs have the capacity to empathize with humans," said lead researcher and behavioral biologist Karine Silva, who explained that the close human-animal bond that’s been developed through 15,000 years of domestication “may have fostered cross-species empathy.”

What does a noisy yawn mean?

My pup is rarely quiet when he yawns. There's almost always a little excited howly-squeak sound when he does it. Although I found quite a few message boards where people weighed in that their dogs also were noisy yawners, I could find no scientific explanation for quiet versus audible yawns.

Coren, however, does break down how to interpret your dog's noises and mentions the "howl yawn" which he describes as a breathy "Hooooooo-ah-hooooo." Coren says the howl yawn translates to, "I'm excited! Let's do it! This is great!" and shows pleasure and excitement when something the dog likes is about to happen.

So maybe my dog's noisy yawn explains the happiness of going for a walk, or a car ride or wrestling with my teenage son. (That also explains why his quiet yawn in the bathtub is a little less giddy.)

Mary Jo DiLonardo Mary Jo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.