Laughter has fascinated humankind since ancient times. We usually associate it with happiness, play and social bonding. For a long time, laughter was believed to be uniquely human but modern research has shown that laughter-like vocalizations also exist in other animals. Great apes, for example, produce sounds similar to laughter during play which are thought to communicate friendly intentions. Interestingly, many of these playful vocalizations resemble panting or exaggerated breathing supporting the idea that human laughter itself may have evolved from heavy breathing during playing. Thus, primates may not be the only animals producing laughter-like vocalizations.

This brings us to dogs, animals famous for their tendency to play, especially with their owners. At the same time, animal welfare scientists are increasingly interested in understanding how animals express positive emotions. After all, how can we know when animals are truly enjoying themselves? Previous research found that dogs produce a special type of pant during playing. The so called “play-pant”, is characterized by strong exhalations and shares similarities with playful panting in primates and human laughter. However, an important question remained: is this pant linked to playful interactions, or is it simply produced during intense emotional states in general? To answer this, we invited 38 dog-owner pairs at the BARKS Lab and recorded them under several emotional contexts: a neutral exploration; playing with the owner; being briefly separated from them and a threatening approach by an intimidating human. We then analyzed and compared the acoustic structure of the pants emitted in each context.

What did we find? Interestingly, play pants sounded different from every other type of pants. They were the noisiest and had the highest pitch. Although noisy vocalizations are often linked to negative emotions, studies on humans suggest that extreme positive events can also generate loud and noisy sounds like the peak of an intense laughter. We also found that play pants had the greatest formant dispersion, an acoustic feature linked to perceived body size. In practical terms, this means that dogs might sound smaller and less threatening while playing, reducing the risk that the interaction will be interpreted as aggressive.

Overall, our study shows that play panting is not simply regular panting produced during excitement. Instead, it may function as a signal of positive and intense emotional states and may communicate that the interaction is friendly and playful. Our findings could have practical implications for animal welfare, by providing an indicator of positive emotions in dogs. More broadly, our results also remind us that features once thought to be uniquely human, such as laughter, might actually be shared among many species. So next time you play with your dog, pay closer attention; your best friend might be laughing with you.