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On this week’s “TechKnow,” contributor Cara Santa Maria looks at the science behind a common claim that dogs are able to detect cancer in humans — often discovered only after a dog’s persistent sniffing or pawing at one body part prompts the owner to seek medical attention. Federally funded studies appear to back this up, finding that trained canines are able to correctly choose which samples (blood, tissue or breath-based) were drawn from people with cancer.
At the University of Pennsylvania’s School of Veterinary Medicine, Dr. Cynthia Otto and the Working Dog Center have been training dogs in scent detection since first treating search-and-rescue K-9 units after 9/11. “I think dogs have always saved our lives,” Otto says, “and I think we're just now recognizing the many ways that they can do that.”
Here are some health conditions that dogs have helped diagnose or treat:
In one study reported by National Geographic, dogs were able to detect breast and lung cancer between 88 and 97 percent of the time.
As reported by “TechKnow,” some dogs such as bloodhounds have as many as 300 million scent receptors, where humans have only five. While humans use the same airway to smell and breathe, when air enters a dog’s nose, it splits into two paths — one for olfaction and one for respiration. Breathing and smelling become two separate functions, so dogs can actually filter scents to a degree that humans can’t begin to comprehend.
Dog cognition researcher Alexandra Horowitz explains it like this in her book “Inside of a Dog”: “While humans may be able to detect a teaspoon of sugar in a cup of coffee, dogs can smell that same teaspoon of sugar in two Olympic size swimming pools.”
In West Hills, Calif., at the InSitu Foundation, dogs are trained — and tested extensively — using breath samples from people with cancer. One challenge is to find and train dogs who are willing to perform the repetitive task of sniffing at hundreds, even thousands, of samples, often as many as 10 times per sample.
One specific type of service dog is a “seizure dog,” which can be trained to bark loudly for attention or activate some other kind of alarm when its owner is having an epileptic seizure. They may also be able to lie down next to a person who is having a seizure in order to help prevent injury.
The science on epilepsy-assisting dogs is still not fully understood. According to the website of Canine Assistants, a nonprofit that trains service dogs for people with physical disabilities or other conditions:
Anecdotal research shows that the dogs are likely responding to an olfactory cue or a certain type of smell. Canine Assistants cannot train our dogs to alert to oncoming seizures. Yet, once a recipient and their dog develop a strong bond, many Canine Assistants seizure response dogs (about 87%) do go on to PREDICT or react in ADVANCE of a seizure, usually with an unusual behavior, such as whining, pawing, pacing, jumping, barking, etc. This may happen a few to several minutes before a seizure, which can be quite helpful for individuals who do not experience an aura or feeling that the seizure is coming on.
Service dogs may be trained or have an innate ability to help detect when a person’s glucose level changes, which can be key for monitoring diabetes.
In December, the Gautreauxs got Shadow, now a 7-month-old Labrador retriever, and nights have become calmer.
"He's doing a great job of alerting me in the middle of the night," she said. "It's really pretty cute. He smacks me in the face and then it's lick, lick, lick. He's very persistent."
One night in mid-March, Shadow kept waking up Gautreaux, but she was confused because Lucien's glucose levels were fine. Soon, though, Lucien began vomiting and Gautreaux took him to the hospital with what turned out to be the flu. Although not trained for it, Shadow had smelled that Lucien's ketone levels were critically high. Ketones in the urine are a sign that your body is using fat for energy instead of using glucose.
A number of researchers and organizations are working with war veterans to study how dogs can help reduce symptoms of PTSD and other combat-related anxiety.
The animals draw out even the most isolated personality, and having to praise the animals helps traumatized veterans overcome emotional numbness. Teaching the dogs service commands develops a patient’s ability to communicate, to be assertive but not aggressive, a distinction some struggle with. The dogs can also assuage the hypervigilance common in vets with PTSD. Some participants report they finally got some sleep knowing that a naturally alert soul was standing watch.
Researchers are accumulating evidence that bonding with dogs has biological effects, such as elevated levels of the hormone oxytocin. “Oxytocin improves trust, the ability to interpret facial expressions, the overcoming of paranoia and other pro-social effects — the opposite of PTSD symptoms,” says Meg Daley Olmert of Baltimore, who works for a program called Warrior Canine Connection.
The new report reviewed dozens of studies, and over all it seemed clear that pet owners, especially those with dogs, the focus of most of the studies, were in better health than people without pets.
“Several studies showed that dogs decreased the body’s reaction to stress, with a decrease in heart rate, blood pressure and adrenaline-like hormone release when a pet is present as opposed to when a pet is not present,” Dr. Levine said.
Pet owners also tended to report greater amounts of physical activity, and modestly lower cholesterol and triglyceride levels. Some research showed that people who had pets of any kind were also more likely to survive heart attacks.
Another study found that “recent research on human-dog interactions showed that talking to and petting a dog are accompanied by lower blood pressure (BP) in the person than human conversation.”