A new study confirms what most dog owners have long suspected: dogs can act jealous, and especially when their human showers another dog with attention.

The study, published in PLoS ONE, suggests that jealousy may be more common among social animals than previously thought. Cat owners, for example, often think that felines suffer from jealousy too.

10 Surprising Facts About Animal Intelligence

The good news is that jealousy indicates the other party really cares.

“Our study suggests not only that dogs do engage in what appear to be jealous behaviors but also that they were seeking to break up the connection between the owner and a seeming rival,” co-author Christine Harris, a UC San Diego psychology professor, said in a press release.

She continued, “We can’t really speak to the dogs’ subjective experiences, of course, but it looks as though they were motivated to protect an important social relationship.”

Harris and former student Caroline Prouvost adapted a test used with 6-month-old human infants. They worked with 36 dogs in their own homes and videotaped the owners ignoring them in favor of a stuffed, animated dog or a jack-o-lantern pail. In both of these conditions, the owners were instructed to treat the objects as though they were real dogs, such as by petting them and talking to them sweetly.

Video: Dogs Have Feelings Too

In the third experiment, the owners were asked to read aloud a pop-up book that played melodies. Two independent raters then coded the videos for a variety of aggressive, disruptive and attention-seeking behaviors.

Dogs were about twice as likely to push or touch the owner when the owner was interacting with the faux dog (78 percent) as when the owner was attending to the pail (42 percent). Even fewer (22 percent) did this in the book condition. About 30 percent of the dogs also tried to get between their owner and the stuffed animal. While 25 percent snapped at the “other dog,” only one did so at the pail and book.

Harris said, “Many people have assumed that jealousy is a social construction of human beings — or that it’s an emotion specifically tied to sexual and romantic relationships. Our results challenge these ideas, showing that animals besides ourselves display strong distress whenever a rival usurps a loved one’s affection.”

Why Dogs Really Do Feel Your Pain

The researchers aren’t certain, but they suspect that social animals, such as dogs and humans, could be hard-wired to feel jealous when another threatens a valued relationship. Some individuals also seem more prone to jealousy.

Usually the jealous party just grumbles (or growls) and mopes, but it is an emotion with far-reaching psychological and social consequences. For example, it often emerges as the third leading cause of non-accidental homicide. Even dogs have been known to attack babies who unknowingly steal away their coveted attention.

The researchers hope future studies will better unravel the causes and internal drivers of jealousy.

Photo: Three Collies. Credit: Steve Harris