A dog may not only fill a home with joy, it fills a home with a whole lot of bacteria, new research suggests.  But that doesn't mean you have to kick your pooch out of the bed.

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This adorable puppy is loaded with bacteria, but those germs may actually be beneficial.

Research from North Carolina State University published Wednesday in the journal PLoS ONE found homes with dogs have both a greater number of bacteria and more types of bacteria than homes without dogs. 

The findings were part of a larger study that analyzed the types of microbes living in 40 homes in the Raleigh-Durham area of N.C.  Participants swabbed nine areas of their homes and informed researchers about aspects that could influence bacterial life, such as whether there were dogs or cats and how many people lived in the home. 

“The project was a first step toward making an atlas of microbes found in the entire home and how they may affect our health and well-being” said Holly Menninger, a co-author and director of public science at NC State’s Your Wild Life program.

Of the places where household bacteria were found, pillowcases and television screens had the most detectable dog-related microbes.

“Some of the microbes we know come from dogs themselves,” said Menninger. “Some of these bacteria come from the outdoor environment, such as dogs bringing bacteria from the soil and into homes.” 

The researchers were able to identify a few classes of bacteria linked to dogs, and certain microbial classes that may cause disease in humans, such as gingivitis and pneumonia.  However, genetic testing of the bacteria was not specific enough to determine whether any harmful strains were there.

All those germs tracked in on dirty paws don’t mean dog-free homes are necessarily healthier, though. While the researchers did not identify the specific species of bacteria living in each household, they were able to say that most of the organisms they found are not disease-causing – and may actually provide some benefits.

“We co-exist with bacteria and healthy, small exposures to bacteria do not pose any risk and might, on the other hand, be beneficial, as long as we keep a good hygienic environment,” said Dr. Rani Gereige, director of medical education at Miami Children's Hospital.  Gereige was not involved in the research.

A recent study found that exposure to a microorganisms from a pet during a child’s first year of life of life may help ramp up the immune system, lowering the risk of developing allergies later. 

“Research has actually shown that mothers who live with dogs while pregnant are less likely to have children with conditions like atopic dermatitis or to develop allergies,” said veterinarian Dr. Andy Roark of Greenville, S.C. 

Certain bacteria from dogs – such as salmonella and listeria -- can cause infections in humans, however, so it is important to be vigilant, he cautions.

“It is always a good idea for both adults and children to wash hands after playing with pets, especially before eating,” said Roark.

The study did not control for certain factors that could affect bacterial growth, such as household climate and cleanliness, and there were not enough homes with cats to accurately analyze the feline contribution to residential bacteria.  The researchers did not analyze whether certain dog breeds harbor more bacteria than others.

The microbes found throughout the different homes fell into three general groups: those that come from skin and live on surfaces we touch, such as door knobs and toilet seats; bacteria linked to food found in kitchens; and organisms found in places where dust gathers, such as television screens and moldings.

Menninger added that the research team is in the process of analyzing samples and other data from a total of 1,300 homes across the United States. 

“We know we have all these bacteria in our home,” said Menninger.  “Let’s learn to live with them.” 

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Maj. Geoff Legler/Oklahoma National Guard/Handout via Reuters

A rescue worker and his search dog sit outside the remains of the Plaza Towers Elementary School in Moore, Okla. Emergency workers have pulled more than 100 survivors from the rubble.

Search teams, including some with trained dogs, are scouring the rubble left behind by the monster tornado that flattened miles of homes, schools and businesses in Moore, Okla., and the nearby area Monday. More than 100 people had been found alive by rescuers as of Tuesday afternoon.

While it's uncertain exactly how many people are still missing, rescuers are up against the clock to find survivors, experts say.

The window of opportunity for someone to still be alive but out of sight under the wreckage is usually about 48 hours, says Bill Dotson, president of the Search Dog Organization of North America. 

“We have got probably until tomorrow night to be optimistic,” Dotson, who has been training search dogs since 1977, said in a telephone interview.  “There is an urgency to this. There is a time factor, but it is always possible that we are going to find somebody," added Dotson, who is not involved in the Oklahoma search and rescue effort.

Authorities said they were still searching Plaza Towers Elementary School in Moore, Oklahoma, where seven children died, but said search dogs had not found anyone else amid the shattered pieces of wood, metal and concrete. Among the searchers are dog units from Texas, Missouri and Nebraska.

Search and recovery experts know it’s possible to survive a building collapse. People have been pulled alive from impossibly small spaces after quakes, explosions and accidents. Most recently, a young mother was pulled alive from the pancaked remains of a Bangladesh clothing factory, 16 days after the disaster.

Slideshow: Tornadoes ravage Plains

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Destroyed vehicles lie in the rubble outside the Plaza Towers Elementary school in Moore, Okla., on Tuesday.

Launch slideshow

The keys to survival are that something must have protected the person from being crushed, they’ll need to be somewhat mobile, they’ll need air and, after a few days, water.

“Voids – we look for voids,”“We look at the wreckage to determine survivability,“ said Dotson, who's helped train dogs for mine rescue, rescues after disaster and to help look for people who are lost or missing.

Survivors will have to have escaped the worst of the flying debris and gotten stuck under a piece of the building’s frame, or something similarly strong and stable.

“Maybe they are buried pretty deep in a basement, a house collapsed on top of it, and nobody could get to them,” Dotson says. “We know from earthquakes that 48 hours is the optimal time to locate living persons and find them alive and get them to hospital.”

Even a minor injury can kill someone after a few days, Dotson notes. “Imagine someone has a cut to the leg. They’re fine, and it stops bleeding on their own,” he says. “Then a day goes by and they start having an infection. Then a second day goes by and the infection’s worse. The mere infection can kill a person who was alive when the tornado left.”

Being completely pinned can also cause what's known as crush syndrome, which severely damages the nerves and muscles. Releasing the victim can even precipitate a heart attack or a stroke, so rescuers must take care.

Specialized equipment can check for the carbon dioxide exhaled by survivors, but it’s usually quicker to use a trained dog.

“They are very successful and very efficient at locating people that you can’t see or hear,” Dotson says. “If someone’s five or six feet down in the rubble, it can be pretty hard to hear them.”

Rescue dogs are specially trained to detect people who are still alive. They can smell exhaled breath, for a start, says Dotson. “Imagine a picture of Pigpen from the Charlie Brown cartoons,” he said. “We all put off molecules that a dog can pick up. Their sense of smell is extremely acute.”

It takes years of training, however – people’s pets are very unlikely to help rescue anyone, even their own families. “They are absolutely, positively of no help whatsoever,” Dotson says.

If someone was trapped for longer than a few days, water would be the next immediate need, experts say. “People can last without water intake, if conditions are pretty good, for around five days or a week,” says Randall Packer, a professor of biology at George Washington University.

Some survivors have said hearing the sounds of the search have given them hope, and the will to hang on.

People can last for weeks without food, but looking at images of the devastation in Oklahoma, Dotson says he doubts any buildings have intact enough spaces for anyone to survive that long.

Fire and rescue officials said they would check every structure in Oklahoma from top to bottom.

“We are always optimistic that the next foot the dog puts down, he is going to say yes, we have got somebody here alive,” Dotson said.

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Knode family

Crystal Knode says her Chesapeake Bay Retriever, Rachel, shown with her 15-year-old daughter, Alex, pays close attention to the family and "anticipates what is going to happen."

Scientists have finally proven what every dog owner knows – our canine friends read our facial expressions like dedicated detectives.

Dogs don’t just depend on verbal commands to figure out what we want, a new study shows. Instead, they look into our eyes and try to guess what we’re up to, according to the study published in Current Biology.

Hungarian researchers showed that dogs will even follow our gaze if we make eye contact with them first.

This study “reveals that dogs are receptive to human communication in a manner that was previously only attributed only to 6-month-old human infants,” said study co-author Jozsef Topal a researcher at the Hungarian  Academy of Sciences.

Topal and his colleagues studied 29 canines. The dogs were shown a movie of a woman who sometimes would stare straight at the dog and call out to him and then turn her head to stare at an object next to her. The other times the woman would just turn her head and stare at the object.

For the most part, dogs who were addressed both through eye contact and with a verbal greeting tended to follow the gaze of the woman in the movie. When no eye contact was made, the dogs didn’t follow the gaze of the woman.

There have been similar experiments in babies, Topal said. And the dogs are behaving just as 6-month-olds do.

The new findings come as no surprise to Crystal Knode, a 51-year-old legal secretary from San Jose, Calif. Her 9-year-old Chesapeake Bay Retriever, Rachel, is always observing family members’ body language and facial expressions.

“She anticipates what is going to happen,” Knode said. “She watches and takes cues to figure out what I’m going to do and what I’m not going to do. Dogs are very attuned to body language and hand motions.”

Topal is convinced that the dogs’ behavior is something that has been bred into the species over its long partnership with humanity.

“Dogs have evolved to sharing their lives with humans,” Topal said. “And they gained new skills that support their social interaction with humans.”

Deleta Jones isn’t buying that analysis. She thinks this is just the way dogs interact – whether it’s with a human or another dog.

“When they learn verbal commands, they are learning a foreign language,” said the 48-year-old dog trainer from Hollister, Calif.  “Dogs normally speak through body language and facial expression. It’s more natural to them.

“If you’ve ever watched dogs at a dog park, you’ve seen it. Within 30 seconds of the time they enter the park a huge amount of information has passed back and forth between the new dog and the ones already in the park. They’re exchanging looks, observing eyes and body posture. In seconds they know who is dominant and who is submissive.”

That skill just transfers to relationships with their owners, Jones said. “If people are upset and crying the dog sees the upset facial expression and also smells the adrenaline,” she added. “Dogs read all of that.”

Video: 'Talking' husky: From YouTube to big screen

So ultimately, babies, until they develop language, are using a communication system that all social animals do. Later on, they’ll lean more heavily on the spoken word, while dogs, cats and horses will continue to rely on body language.

People sometimes forget that body language is the more natural mode of communication for their pets, Knode said. If you really want to have a conversation with your pet, tune in to their language, she says.

“You have to try to communicate on their level, what they understand,” Knode said. “They have their own language and you just have to try to communicate and think as they would think.”

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Tank, an English Bulldog, dressed as the Runaway Bride for the 21st Annual Tompkins Square Halloween Dog Parade in New York this month. Dressing up is fine, but keep dogs away from Halloween candy that may contain xylitol, a sugar substitute that can be dangerous or deadly to canines.

Keeping kids from overdosing on candy is every parent’s Halloween duty, but pet experts warn that the vigilance should extend to the furry members of the family as well.

That big bag of candy, gum and other treats hauled home from trick-or-treating can be dangerous -- or even deadly -- to dogs and some other pets, particularly because so many goodies now contain xylitol, a sugar substitute found in a growing number of sweets.

“Halloween is kind of the prime day for xylitol poisonings,” said Karen Leslie, executive director of The Pet Fund, a non-profit animal medical care agency. “This can be a very small exposure and a very big problem.”

The federal Food and Drug Administration earlier this year warned consumers about the dangers of xylitol poisoning in dogs and ferrets.

Just a single stick of gum could endanger a 10- to 20-pound dog, cautioned Eric Dunayer, an expert on xylitol poisoning and an associate professor of clinical sciences in the School of Veterinary Medicine at St. Matthew’s University, Grand Cayman. The amount of xylitol varies widely among foods, with those that contain less than 2 percent of the substance posing less risk.

In dogs, xylitol stimulates a massive release of insulin, causing a drop in blood sugar, which can lead to weakness, loss of coordination and seizures, Dunayer said. Xylitol also can lead to liver damage and death in rare cases. Symptoms can occur within 30 to 60 minutes of ingestion of xylitol and require immediate veterinary attention.

Reports of xylitol problems have been steadily rising for the past several years, said Tina Wismer, a veterinarian and medical director at the poison control center operated by the American Society for the Prevention of Cruelty to Animals, or ASPCA.

In 2010, the agency received more than 2,500 calls from owners frantic because their animals had ingested toxic treats. That's probably a fraction of the actual incidents, which are more likely to be reported to local vets.

“We tend to get a lot of gum calls,” Wismer said. “We can also find xylitol in other candies and mints.”

Visits to animal emergency clinics rise dramatically around Halloween and other candy-centric holidays, said Joan Dolance, a veterinarian and director of emergency care at the Animal Surgical & Emergency Center in West Los Angeles. She still recalls treating a Yorkie who ate an entire pack of gum found in his owner's purse.

"He was very sick, but he eventually recovered," she said.

Chocolate is a better-known poisoning culprit, but many pet owners still don't know about the dangers of xylitol, the experts added.

There is no antidote for xylitol poisoning, so veterinarians typically try to induce the pet to rid its system of as much of the dangerous product as possible. Activated charcoal, which is often used to treat other types of poisoning, may help, but some pets wind up hospitalized and on intravenous fluids for at least 24 hours, said Dolance.

The best treatment is prevention, of course, the experts say. Pet owners should keep xylitol-containing treats out of reach of animals. And they should check the ingredients on common foods such as pudding, Jell-O gelatin and baked goods, to make sure they're not sharing bites of xylitol-laced human food with their dogs.

With all of the chaos of parties and costumes and treats, pet owners should be especially cautious on Oct. 31, added Leslie, of the Pet Fund.

“Halloween is the one day we make sure they get nowhere near the candy," she said.

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