Dogs that sniff out diseases could help develop AI tools to diagnose cancer

It takes less than a second for the fox-red labrador Hetty to decide whether the urine sample comes from a patient with bowel cancer. Moving briskly down the line, he dismisses the first three after a brief sniff, but catches attention in the fourth.

Trainer Mark states his indication and Research Co-ordinator Steve confirms that this sample came from a patient at Hull NHS Trust with advanced stage four bowel cancer. As a positive reinforcement, there is a click and Hetty gets a tasty treat.

The six-year-old super sniffer is the latest class of talented pooches that Medical Detection Dogs teaches to recognize the smell of diseases. The Daily Express visited the charity’s Milton Keynes base to witness its fascinating work.

A dog’s sense of smell is up to a million times stronger than a human’s, so it can detect a teaspoon of sugar in two Olympic-sized swimming pools.

Hetty is part of a six-person team that learns to identify the smell of colon cancer. Their efforts will initially confirm whether it can be accurately detected in human urine.

READ MORE: “I ignored these symptoms and got a devastating cancer diagnosis”

If possible, the data collected during training could provide crucial insights into the compounds the dogs are sniffing – which in turn could be targeted using diagnostic technology.

Electronic noses, which seek to identify odors by analyzing their chemical profiles, have been developed since the 1980s. There is one major hurdle in using them to detect cancer.

As the charity’s chief executive Dr Claire Guest said: “Right now, a dog is the only thing on the planet that knows what cancer smells like.”

Every time Hetty goes down the sample line, the urine-holding racks collect data, including how much pressure she uses with her nose and the duration of each sniff.

A graph showing his interest when he identified a stage four colon cancer sample shows one colored spike in each of the first three spots, then a double white spike in the fourth, indicating that he stopped to smell the second one.

This information could eventually be used to teach an AI tool exactly what bowel cancer smells like.

Dr Guest said: “It’s not about hundreds of thousands of dogs sniffing samples around the world. It’s about using a learning algorithm to understand what are good examples of a smell.

“You can start to see from the dog whether he’s saying ‘this is a great example, smells exactly like cancer’ or ‘this might have come from someone with cancer, but there’s no smell of cancer’. There’s a huge amount of information being generated.”

The charity has also attracted interest from NHS clinicians who are willing to use dogs to test urine samples, particularly from patients being monitored for bowel cancer recurrence.

Dr Guest added: “The dog would never make the decision, but the dog could inform the decision maker.”

Medical Detection Dogs was launched in 2008 after Dr. Guest decided to find out how well dogs can smell diseases.

She said: “I started working for an assistance dog charity and met a woman who told me a story about a Dalmatian who had started licking and sniffing a mole on her calf constantly.

“That made him go to the doctor. The mole was removed and it was malignant melanoma. From the day of that story, I said, ‘I have to find out how this happened.’

Behavioral psychologist Dr Guest, 60, joined forces with orthopedic surgeon John Church. Their pioneering research showed that dogs can distinguish the urine of healthy people from those with bladder cancer.

His own dog, Daisy – another foxy Labrador – was trained in that study and later on prostate cancer. One day Daisy started acting strangely, poking Dr. Guest’s chest and staring.

She visited a general practitioner and was diagnosed with a deep-seated and difficult-to-diagnose form of breast cancer. Dr Guest said: “Had I not been aware of it, both my surgeon and oncologist said my prognosis could have been very different.”

Around the same time, anecdotal evidence was mounting that some dogs knew when people with diabetes were close to low blood sugar.

Thus, Medical Detection Dogs was born both to train personal assistant dogs and to explore their potential as four-legged diagnostic tools.

Dr Guest added: “Having support for the idea that dogs could actually give science information about the smell of cancer, it was much more sceptical.”

Additional studies followed on malaria, Parkinson’s disease, Pseudomonas bacteria and Covid. Fifteen years later, the charity is on the brink of its most exciting discovery yet.

Another project could turn screening into a common disease that causes tens of thousands of hospitalizations among the elderly each year.

Two-year-old black Labrador Meg is one of those who learned to recognize the smell of urinary tract infections (UTIs).

This work was inspired by the team’s Covid research, which found the best-performing dog detected the coronavirus with 94 percent sensitivity—higher than the lateral flow test.

Medical Detection Dogs were deployed directly to screen people for the first time during the pandemic, visiting the power plant twice a day to check workers for Covid for several weeks.

The work ended with the easing of testing requirements, but the information obtained is now used to fight urinary tract infections.

The charity’s vision is to create a hub network across the UK where teams take dogs into care homes and social groups to report potential UTIs early, before serious complications arise.

As a pilot project, the staff has already started visiting groups of the elderly and “health on the main street” centers.

A clinical trial to validate the method could start next year, Dr Guest said, adding: ‘We are about to give NHS ethics. [approval].”

While they may not be the magic bullet to delay NHS cancer diagnosis waits, it’s clear that biological detection dogs have a lot to teach us about the smells associated with human disease.