Do dogs cry?

In this study, researchers found that when dogs are reunited with their owners, their tear volume increases significantly. This increase in tear volume was not present when dogs were reunited with familiar non-owners. The researchers also found that applying an oxytocin solution to the dogs' eyes increased tear volume, suggesting that oxytocin may play a role in tear secretion during owner-dog reunions. Additionally, human participants rated photos of dogs with artificial tears more positively than those without. These results suggest that emotion-elicited tears may facilitate emotional connections between humans and dogs. Dogs are known to have social-cognitive skills similar to humans and their gaze is thought to stimulate oxytocin secretion in humans, which is important in bond formation. It is possible that tears in dogs' eyes during reunions with their owners may facilitate human caregiving behavior.