Dogs Remember Our B.O. When We're Away

The scent of a familiar human -- even that person's stinky sweat -- lingers happily in the minds of dogs. Continue reading →

Dogs fondly remember us - even our B.O. - when we're not around, suggests a new study on how dogs respond to the scent of a familiar human.

The research, published in the latest issue of Behavioral Processes, was the first brain-imaging study of dogs as they responded to smells of other dogs and people.

Ugliest Dog Contenders: Photos

"It's one thing when you come home and your dog sees you and jumps on you and licks you and knows that good things are about to happen," project leader Gregory Berns said in a press release.

"In our experiment, however, the scent donors were not physically present. That means the canine brain responses were being triggered by something distant in space and time."

When we smell the perfume or cologne of someone we love, the reaction may be immediate and emotional and not necessarily at a conscious level, Berns, who is director of the Center for Neuropolicy at Emory University, added. "Our experiment may be showing the same process in dogs. But since dogs are so much more olfactory than humans, their responses would likely be even more powerful than the ones we might have."

If you have a dog, your unique smell could very well be the best thing that your dog has ever whiffed.

The study involved 12 dogs of various breeds. The animals had all undergone training to hold perfectly still while undergoing an fMRI scan (probably the hardest part of this study).

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As the dogs were being scanned, they were presented with five different scent samples from the following five sources: the dog itself, an unfamiliar canine, a familiar canine that lived in the dog's home, an unfamiliar person, and a person who lived in the dog's household. The latter wasn't the owner because those people had to serve as handlers throughout the experiment, and the researchers didn't want the scents to come from a dog or person that would be present in the same room as the experiment was taking place.

Here's the rather gross part. The dog scents were swabbed from the rear/genital area and the human scents were taken from armpits. This bothered the people more than the dogs, though.

"Most of the dog owners and handlers involved in the experiment were women, so most of the familiar human scent donors were their husbands," Berns says. "We requested they not bathe or use deodorant for 24 hours before taking the sample. Nobody was too happy about that."

The results showed that all five scents elicited a similar response in parts of the dogs' brains (the olfactory bulb and peduncle) involved in detecting smells. The responses, however, were significantly stronger for the scents of familiar humans, followed by that of familiar dogs. Canines that had received training as service/therapy dogs displayed the most positive reactions to the human smells, perhaps due to genetics or because the connection to people had been fostered through more training.

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Berns said that the reactions to familiar people "suggested that not only did the dogs discriminate the familiar human scent from the others, they had a positive association with it. While we might expect that dogs should be highly tuned to the smell of other dogs, it seems that the ‘reward response' is reserved for their humans. Whether this is based on food, play, innate genetic predisposition or something else remains an area for future investigation."

Some might just happy to know that dogs pay attention to us and likely think well of us, even our stinky unique scent, when we are away. The scientists, though, have further research goals in mind.

"In addition to serving as companion animals for wounded veterans, dogs play many important roles in military operations," Berns said. "By understanding how dogs' brains work, we hope to find better methods to select and train them for these roles."

Image: A dog's nose remembers you best. Credit: iStockPhoto

The World's Ugliest Dog Contest celebrates its 25th anniversary today at the Sonoma-Marin Fair in Petaluma, Calif. Twenty-five plus "beauty challenged dogs are foregoing their usual beauty regimens in preparation," according to producer Vicki DeArmon.

"They are so ugly they are cute," DeArmon told Discovery News.

This year's contenders include pedigree and mutt mixes of Chihuahua, Chinese Crested, Boxer, Terrier, Pug, Poodle and Peruvian.

Chupee and other competitors are vying for a $1500 cash prize, a trophy "and an instant launch into worldwide acclaim," DeArmon said.

"The dogs are judged on their initial horror effect on the audience," shared DeArmon, who is the author of the recently published "World's Ugliest Dogs: The Official World's Ugliest Dog Contest Book."

"They are also judged on their personality, such as how the dog struts across the stage or how its tail wags during the competition."

Human breeding efforts have, in many cases, resulted in some of the "ugly" breed characteristics and health problems of certain dogs. Many of the competing dogs, however, were adopted from shelters.

At least one former World's Ugliest Dog has an actor's guild card and has starred in horror movies, DeArmon shared. "Media interest in this contest has been phenomenal," she said. "Dogs become famous overnight."

All dogs must enter a prequalifying round to ensure that "they are truly ugly before they take the stage." DeArmon said that sometimes she and others cannot even tell if candidates in the "mutt" category are really dogs or not, so that's yet another matter that must be confirmed in advance.

Owners must provide veterinarian documentation that their dogs are healthy when registering. The fair additionally conducts on-site vet checks on the day of the contest.

Rascal is "ugly dog royalty," according to DeArmon. Both his mother and grandmother formerly held the World's Ugliest Dog title.

More than 50 percent of the contestants have never competed before. In past contests, the winner is usually a wild card from the new entries. Last year, a dog from the U.K. -- bedecked in a Union Jack -- won over the audience.

"The contest keeps getting bigger and better every year," said DeArmon. "The dogs seem to be getting uglier too."