Dogs: they cry with joy when they see their owners again

THE dogs howl as men for the luck. An example is when they see their masters again.

We have found that howling dogs and tears are associated with positive emotions. We also found that oxytocin is the possible mechanism behind the phenomenon. We had never heard of animals howling in joyful situations, such as when they are reunited with their owners, and we all knew this would be a world first.

Takefumi Kikusui of the University of Azabu

The expert made his discovery when his dog was breastfeeding. Kikusui explains that the presence of tears in the eyes is due to theoxytocin causing the tear sac to expand. Oxytocin is better known as the love hormone. Oxytocin is released thanks to the relationship between dog and owner. Here, an experiment was conducted in which the dog and its owner interacted with careful observation of the cracks at the dog.

Then a standard test was performed to measure the volume of dogs’ tears before and after assessing the owners. The volume of the lacrimal sac increased significantly when they assessed the human known to them. With the addition of oxytocin to the dogs’ eyes, the volume of their tears also increased.

Oxytocin therefore plays a key role in tear production when humans and dogs get back together. Then, some people were asked to rate photos of dog faces with and without artificial tears. The reactions were more positive when they saw the dogs with teary eyes. The production of tears creates an even stronger bond between humans and their dogs.

It seems that dogs produce tears in situations that people consider happy. Now, further studies will focus on understanding whether dogs also produce tears because of negative emotions and whether they cry when they find their fellow humans. In short, understand the social function of tears. For now, though, it seems to only have links on the human-dog relationship.