A dog tail (Photo: iStock | Courtesy of Vetstreet )

It’s certainly not for a lack of effort on the dog's part: Recent studies have shown that our faithful companions can track human eye movements, sniff out diseases — sometimes before our doctors do — and wag their tails differently for their owners.

But since dogs haven’t mastered English yet, there’s a good deal of mind reading required when it comes to understanding canines.

“With dogs and owners, it is not so much a dialogue but a monologue,” says Anders Hallgren, a Swedish animal psychologist and the author of The ABCs of Dog Language. “Owners take over the communication and don’t listen or don’t read what the dogs are saying.”

From half-moon eyes to demand barking, there are myriad ways that our four-legged wonders try to communicate with us every day.

The Eyes Have It
“If you look at dogs’ eyes, you can see so much,” says Hallgren. “There are so many muscles around each eye that they can quickly change from attack mode to flight mode to ‘I’m starving mode' — especially if they’re near the table.”

One commonly misinterpreted eye movement is what animal psychologists call "half-moon eyes."

“You often see this when children hug a dog,” says Karen Pryor, author of Reaching the Animal Mind. “The head is lowered and turned away, and the whites of the eyes are showing, which is like us clenching our fists because we hate what’s happening to us."

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In addition to telegraphing their own needs, dogs also seem to have an ability to read our minds. According to a new study, this isn’t actually doggie ESP, but the result of some rather keen powers of observation.

Researchers recently recorded dogs tracking humans’ eye movements, as if trying to decode intent — a phenomenon akin to a baby watching his parents. “Dogs are receptive to human communication in a manner that was previously attributed only to six-month-old human infants," coauthor Jozsef Topal told Discovery News. “They can play the role of being a child substitute.”

And, just like babies, our favorite fuzz balls may even be able to read human expressions.

In a study conducted at Azabu University in Japan, dogs were shown photos of their owners either smiling or with neutral expressions on their faces. The canines were trained to only identify photos of smiling owners. When they were shown photos of non-owners, many of the dogs still flagged pictures of humans who were smiling.

This behavior isn't necessarily innate to canines — who usually equate bared teeth with aggression — but it's one that may have been learned thanks to constant contact with humans.