Why do dog’s yawn? No, that’s not a question akin to “Why did the chicken cross the road?” It’s actually quite interesting because a definitive answer remains elusive.

Scientifically speaking, the jury is still out on why any of us yawn. The trait is widespread throughout the animal kingdom (even fish yawn) and can even be observed in fetuses still in the womb. Researchers have looked into its role in respiration, arousal, thermoregulation, and communication, but nothing definitive has yet been found. Since science hasn’t been able to answer the question, I’m going to look at the situation from a practical standpoint.

First, I think it’s obvious that all of us (dogs included) yawn when tired, even if we don’t yet know the reason why. If your dog has had a long day or just awoke, is drowsy or fatigued, and yawns, you don’t have to look much further for an explanation.

But here’s a different scenario where being tired isn’t to blame. Dogs will also yawn when they are stressed. Usually, these yawns are associated with other signs of stress like lowered ears, squinting eyes, and tense muscles. Yawning is one of the signs that I look for when dogs interact. Stress is much more common than sleepiness under these conditions, so if a dog yawns around an unfamiliar or assertive individual, it’s time to put some distance between them.

Yawning as a form of communication between individuals is also supported by the phenomenon of contagious yawning. Dogs can even “catch” human yawns, and studies have linked these incidents with empathy. One even found that dogs were more likely to yawn when exposed to the sound of a familiar person yawning (the person was not actually present) in comparison to the sound of an unfamiliar person yawning.

My guess is that yawning serves several functions. It probably started as a physiological process, perhaps to more fully expand our lungs when we are tired and taking more shallow breaths than we do when we are alert and active. Then it began to take on a role in communication, very much the way that urination and defecation are primarily physiological process for dogs but are also used as communication tools via scent marking.

I still have a question though. Why have I been yawning my fool head off as I’ve been writing this post (there goes another one). Sure, I’m not being active and am a little tired, but I wasn’t yawning nearly as much when I was writing on another topic just a few minutes ago. Yawning while reading “yawn” is a well-recognized experience, and now I can attest that writing the word has the same effect.

How many times did you yawn while reading this post? Did your dog yawn too?

Dr. Jennifer Coates

Image: Tim Lucas / via Flickr