Dogs have long been renowned for their incredibly receptive noses, but we are only just beginning to grasp how extraordinary the canine sense of smell really is. “Man’s best friend” might be able to save countless lives—just by sniffing.
In recent years, the medical community has begun to explore the potential for dogs to detect subtle changes associated with various disease and conditions such as diabetes, epilepsy, allergies and certain types of cancers. These medical detection dogs, as they are called, offer a promising new frontier in the world of healthcare.
“In our work [with diabetics], dogs are not taught to react to symptoms but to scent,” says Ralph Hendrix, Executive Director of Dogs4Diabetics in Concord, California, an organization that trains Medical Assistance Diabetic Alert Dogs and places them with insulin-dependent diabetics to assist them in managing their insulin therapy.
Because of chemical changes that occur within the body, many diseases have a unique scent that can be detected on the breath or in sweat. Dogs can smell between 1000 to 100,000 times better than humans, says Hendrix. By harnessing the ultra-sensitive canine sense of smell, researchers can train dogs to detect the presence of certain diseases or alert humans prior to the onset of medical events, such as hypoglycemia.
The diseases they smell
AtDogs4Diabetics, dogs are taught to smell scents associated with changes in blood sugar, or glucose. High blood sugar, or hyperglycemia, causes breath to smell fruity (think Juicy Fruit gum), a change even humans can detect. Although low blood sugar, or hypoglycemia, also creates a distinctive scent, humans can’t smell it, but dogs can if they are trained to recognize the scent collected from diabetic breath or sweat.
“The dogs can smell the onset of a hypoglycemic event about 15 to 30 minutes before it is measurable by a glucose meter,” says Hendrix.
Dogs are also being trained to sniff out various forms of cancer. For example, in a 2011 study at Medical Detection Dogs, a charity in England, researchers found that dogs could identify volatile organic compounds (VOCs) on people’s breath, which change during the early stages of bladder cancer.
The dogs’ cancer work was influential in the 2013 creation of a device, The Odoreader, which uses a sensor to detect chemicals related to bladder cancer in gas created from urine. In a study, the Odoreader accurately sorted 24 cancer samples from 98 non-cancerous ones.
In 2011, researchers at Schillerhoehe Hospital in Germany found that dogs could detect lung cancer, again through the presence of VOCs on the breath. Out of 220 volunteers, some with lung cancer, the dogs correctly identified 71 lung cancer samples out of a possible 100.
Yet another device, Na-Nose, created by Technion-Israel Institute of Technology and manufacturer Alphaszenszor, was also inspired by the dogs’ example. Patients breathe into a tube, and the device analyses its gases, detecting cancer-related VOCs.
“Dogs are also taught to help people with allergies such as peanut or latex allergies avoid [accidental] contact with those items,” says Hendrix. And medical detection dogs can be trained to alert a person of a coming seizure, such as an epileptic seizure.
How the dogs do it
Teaching a dog to discern a specific scent takes months of training. The dogs that work with diabetics, for instance, must first learn to detect the scent of low blood sugar on a diabetic’s breath or sweat. “Then he has to be taught through games and training exercises to discriminate the hypoglycemic scent from other distracting scents,” says Hendrix. “The dogs receive positive rewards for identifying the correct scent.”
But that’s just the start. The dogs then have to learn to spot the “live” scent of low blood sugar apart from the “dead” scent that lingers throughout a diabetic’s home. “The dog has to learn to detect the scent in different environments such as home, work, or in public,” says Hendrix.
The dog also has to be taught to alert the diabetic. He does this by placing a device called a bringsel that hangs from his collar into his mouth whenever he smells the live scent of low blood sugar. The diabetic then checks her blood sugar, and if the dog was accurate, praises him to reinforce his training.
How to get a medical detection dog
Hendrix suggests that people begin by getting in touch with Assistance Dogs International (ADI), an accreditation agency for assistance dog organizations. ADI offers access to accredited trainers who can help find a dog. The ADI site also offers information about what to look for in a trainer and dog. Dogs4Diabetics also offers information about standards for selecting a medical-detection dog provider.
Many medical assistance programs are non-profits that give the dogs to those who need them most for a minimal fee. Dogs4Diabetics, for instance, charges $50 to apply and $100 for training materials. The costs–around $25,000—of training the dogs are met through donations to the program.
“Our clients receive over 130 hours of classroom and field training prior to placement,” says Hendrix. “And we require clients to return to the center to re-certify the dogs annually.”
The organization receives more than 10 times the applications for dogs than it can provide. It has a minimum two-year waiting period, not unusual for such organizations.
Although people can buy dogs outright, which sell for $20,000 or more, Hendrix doesn’t advise it. “No one should pay this type of money for a dog without long-term support and follow-up services to ensure that the dog will work properly. Do your research and consult with a reputable third-party trainer before buying a dog.”