If you’ve ever returned home to be greeted by your dog with licks and a wagging tail after being gone for a long time, it’s possible that your dog feels the same way about you.
According to the findings of a limited study that were published on Monday in the journal Current Biology, researchers found that dogs shed more tears when they were reunited with their owners than when they were with other humans. If what you say is accurate, this would be the first piece of evidence to suggest that dogs aren’t the only non-human creatures capable of shedding tears as a result of emotional experiences. Researchers who weren’t involved in the research are sceptical that the findings support the conclusion that was drawn.
The fact that people assessed photos of dogs with fake tears in their eyes more highly than pictures of dogs without tears was another conclusion of the research, although sceptics were less worried by this discovery.
The authors of the research did not propose that dogs experience emotional crying in the same way that humans do. Takefumi Kikusui, a specialist in animal behaviour and veterinary medicine at Azabu University in Japan who was also one of the authors of the research, stated that when dogs display “watery, glistening eyes,” it “facilitates human caregiving.” This was one of the findings of the study.
Previous research has demonstrated that dogs have a strong knowledge of the emotions that humans are feeling. According to Dr. Daniel Mills, a veterinary behavioural medicine specialist at the University of Lincoln in England who was not involved in this study, scientists have also established that dogs have emotional categories such as “You are somebody I care about, therefore, I’m pleased to see you,” and “You are somebody I don’t care about, so I can ignore you most of the time.” These are just two examples of the emotional categories that dogs have been shown to have.
In the recent research, scientists evaluated the amount of tears shed by dogs at their baseline, and then compared those results to the amount of tears shed by the dogs after they were reunited with their owners after being apart for many hours. They also assessed the amount of the dogs’ tears after the canines had interacted with a member of the day care staff. The comparative experiment was carried out using twenty dogs as participants.
Dr. Mills explained that veterinarians measured the canine waterworks using a Schirmer’s test, which is a diagnostic tool for determining whether or not a dog has dry eye syndrome. During this procedure, a sheet of filter paper is held in place for one minute between the lower eyelid and the cornea of a dog. The volume of the tears increases in proportion to the distance they travel on the paper.
Dr. Wynne has doubts about the ability of this procedure to establish a connection between emotional state and tear production. When a dog is overjoyed to see its owner again, it may wiggle about more than usual, which may cause the paper to brush against its eye more, which in turn may cause the dog to shed more tears. His response was, “So, I don’t buy it.”
Dr. Kikusui, on the other hand, said that the diverse experimental circumstances did not affect the quantity of paper rubbing that the dogs’ eyes were subjected to.
Researchers have also explored how the hormone oxytocin plays a part in the attachment that develops between humans and dogs. In the study that Dr. Kikusui and his colleagues conducted and had published in Science in 2015, they demonstrated that an increase in oxytocin would occur in a dog when it was reunited with its owner. In point of fact, the researchers discovered that the levels of oxytocin increased in both the dogs and their human owners as they gazed at each other.
The lacrimal gland, which is responsible for tear production, was stimulated to produce more tears by the researchers by giving the dogs an injection of oxytocin. After that, the volume of the dogs’ tears was assessed, and the results showed that dogs administered oxytocin had more tears in their eyes than dogs given a control drug. According to what the authors of the research noted, this suggests that oxytocin has a role in the phenomena of moist eyes.
To throw a wrench into the works, or maybe a bone, Lauren M. Bylsma, a clinical psychologist at the University of Pittsburgh, noted that administering oxytocin or the control solution directly to the eye might have caused irritation to the dogs’ eyes.
Dr. Bylsma is one of the co-authors of a study published in 2018 titled “Why Only Humans Shed Emotional Tears,” and she maintains her stance on the topic. Dr. Wynne does, too.
Despite the fact that Dr. Mills has questions about the authors’ techniques, she agrees with the authors’ overarching conclusion that tears may play a part in the bonding process between humans and dogs.