We’re Not Crying, You’re Crying!

Do you know why dogs get teary-eyed?

A new study by Professor Takefumi Kikusui from Azabu University and colleagues demonstrates that our furry friends may be more like us than we think. According to the researchers, dogs may have gained human-like social-cognitive skills through the years they have accompanied us. It turns out that they excel at communicating with their eyes!

The researchers note that tears convey important non-verbal messages among humans. However, there have not been any studies investigating emotional tears in animals until now. To create an emotionally stimulating condition for dogs, Kikusui and the research team designed a “reunification experiment with dog owners.”

In the first experiment, the experimenters measured dogs’ tear volumes using a test called Schirmer Tear Test before and after reunions with owners and familiar non-owners. The dogs’ tear volumes were measured at reunion with their owner after about 5 – 7 hours of separation. Compared with a baseline measure of tear volumes, the dogs teared up significantly more when they reunited with their owners. However, repeating the experiment with a non-owner did not lead to more tears in dogs.

Then, oxytocin and a control peptide solution were applied to the dogs’ eyes to assess the role of oxytocin in animal tear production. The results pointed to an increase in tear production in dogs that received the oxytocin but not the peptide solution. Also known as the “love hormone,” oxytocin plays an important role in trust, romantic attachment and parent-infant bonding. 

Finally, the researchers presented people with photos of dogs that either had artificial tears in them or not. People actually rated photos with teary-eyed dogs as more positive. What this finding suggests is that tears may encourage people to be more caring toward dogs. 

Overall, the study highlights key information regarding how dogs have learned to communicate with their human friends through their eyes. And we think it is working, don’t you agree?