The Promising Science of Canine Medical Scent Detection

By Taylor Ham

Meet Stewie.

Stewie is a seven-year-old Australian Shepherd with a passion for Frisbee, tennis balls, and the ability to detect early stage lung, ovarian, and breast cancer. To see her work is to feel an extraordinary sense of hope. She is confident and eager as she enters the lab room and moves among the samples laid out before her, sniffing each in turn before decisively sitting down in front of one, her tail twitching eagerly at the tennis ball reward she knows will come. This incredible girl is part of a team of dogs—many of whom have been rescued—who go to work every day to help researchers advance the science of medical scent detection that will one day save lives.

Cancer accounts for nearly 1 of every 4 deaths in the United States. It is a disease that has touched so many of our lives, and yet one that we know tragically little about at its earliest stages. Despite technological advances, there are still no accurate screening methods to detect the beginnings of many potentially treatable cancers. The screening methods that are used today are not only costly, but also carry the risk of false negative or false positive results, both of which can be devastating to a patient and his or her family. As the medical community continues to search for solutions, a growing number are turning their attention to a surprising source of hope—man’s best friend.

The Numbers and The Nose
Can dogs really detect cancer? According to Dina Zaphiris, who has now trained more than 50 dogs to do it, the answer is an emphatic yes. “People who have read the research agree that there is no denying that dogs can do it,” she says. Dina is Stewie’s human partner; a professional dog trainer who gave up a successful career as a behavioral expert and trainer to the stars in Los Angeles to dedicate her life to advancing the science of medical detection using the amazing olfactory sense of dogs.

For Dina, this mission is personal. Shortly after her own mother was diagnosed with stage 3 breast cancer, she was contacted by Dr. Michael McCulloch to collaborate with the Pine Street Foundation on a study that involved training dogs to detect early and late stage lung and breast cancer through sniffing breath samples of patients. In this double blind study, five dogs were trained to detect cancer by ignoring healthy control samples and sitting or lying down next to the one originating from a patient diagnosed with cancer. The results were astounding. In a matter of months, five ordinary household pets with only basic obedience training were detecting lung cancer with 99% accuracy and breast cancer with 88% accuracy, with almost no false positives in either case. Even more promising is that the dog’s ability to detect cancer was consistent across all four stages of the disease with no change in accuracy levels.

The results of this first study were published in 2006 in the peer reviewed Journal of Integrative Cancer Therapies, and were a springboard for more than 500 replication and validation studies conducted throughout the world. The significance of this early research is in proving that volatile organic compounds in cancer cells actually have a smell, and that dogs can be trained to recognize it by sniffing human samples. Currently, doctors use sight, sound and touch to diagnose cancer in patients, often at more advanced stages of the disease. The results of this research have the potential to change the way we go about diagnosing disease by adding a fourth sense—smell—to help us detect cancer even in its earliest stages. This could mean finding ways to integrate working dogs directly, or learning from their extraordinary scenting abilities to develop new screening tools that function as “electronic noses” to sniff out chemical compounds that signal the presence of cancer.

Dina ended up losing her mom to cancer during this time; an emotional event that changed the course of her life. She moved from Los Angeles to Chico, California, to be closer to UC Davis, where she began collaborating in earnest on creating a center for bio-detection. “I would give up anything to do this and see it done,” she says.

An Uphill Climb
Despite its promise, the road to realizing the practical benefits of this research can seem painfully slow. Barriers to advancing the science of canine medical detection include persistent misinformation, a general lack of awareness, and funding constraints preventing the undertaking of more large-scale studies. Limited funding and little collaboration between the key players also allow for a continued level of skepticism. “The problem with the science is that dog trainers are not doctors and doctors are not dog trainers,” Dina says. “All of us—olfactory scientists, dog trainers, PhDs, and medical professionals need to help each other move this forward in a meaningful way.”

In an attempt to address these issues, Dina founded the In Situ Foundation, a 501(c)(3) non-profit organization that collaborates with medical centers and universities to conduct research in canine medical detection. The Foundation has created the first medical protocol for the selection, training, and handling of a medical scent detection dog, and now offers certification for dog trainers interested in learning the techniques.

Envisioning The Future
When referring to cancer, “in situ” means cancer cells that have not metastasized, or spread. Dina’s vision is that one day dogs will be able to provide an effective, low-cost, and non-invasive screening method for early stage cancer that will give patients an opportunity to be treated early and go on to live their lives cancer free.

The next big step for In Situ is to bring the science to life in a practical way, a prospect fraught with legal barriers. “It is really frustrating to see your dogs do something amazing everyday and not be able to use it to help people,” Dina says. She believes that eventually our society will have to take the risk in screening people. In Chico, that leap will happen soon, as In Situ teams up with local fire departments to screen breath samples from firefighters—a population that has three times the likelihood of developing cancer than the general public.

“When I was little,” Dina remembers, “my mom made a rule in the house that I wasn’t allowed to say ‘what if.’ But only the people who say ‘what if’ have found cures, treatments, and screenings. Someone has to take the risk. I say, ‘What if this is possible?’” ND

Taylor Ham is a writer and dog lover who spends her free time exploring new places and smells with her rescue hound, Daisy.



Put Your Paw In
Inspired by the heroic feats of medical scent detection dogs? You can support these amazing pups and the people who work with them by donating to research centers like the In Situ Foundation ( and the Penn Vet Working Dog Center ( Or consider supporting a local service dog organization that trains and places medical alert dogs with families who need them. Check out and



Beyond Cancer
While canine cancer detection is contained largely to the lab at this point, many dogs are already putting their noses to work to helping their humans manage a range of other medical conditions in amazing ways:

Diabetes: Specially trained service dogs placed with diabetic individuals can detect the high and low blood sugar well before an electronic monitor, simply by sniffing the sweat of their human handlers.

UTI Infections: Research has shown that dogs can be trained to detect the presence of E. Coli in urine samples—bacteria that can cause significant medical problems, particularly for individuals with neurological issues and the elderly.

• Allergens: Individuals with peanut or other life-threatening allergies may gain freedom and peace of mind from a service dog trained to alert to the presence of invisible allergens in the air.

• Addison’s Disease: Dogs have been trained to detect minute hormone-related odor changes to alert sufferers of Addison’s of a potential oncoming crisis, or the need for medication.