These Amazing Dogs Can Smell Cancer

Dogs can use their noses to sniff out bombs and drugs, lead manhunts for murderers, and rescue people from disasters. And, now, they can even diagnose diseases.

Researchers at University of Pennsylvania's Working Dog Center are training a team of retrievers and Dutch or German Shepherds to use their extremely sensitive noses to sniff out ovarian cancer.

If they are successful, the research could lead to the development of a new device that could save thousands of lives every year in the U.S. alone. Also, they are completely adorable.

As with many cancers, detecting ovarian cancer early is crucial to survival. The five-year survival rate for ovarian cancer is high (around 90%), but, as with many cancers, early detection is crucial. Though it is only the eighth most common type of cancer, it is the fifth most common cause of cancer-related death. That's because about 70% of the time doctors don't detect the cancer until it has spread.

Life-saving scents

Training dogs for scent detection works through a simple but lengthy process called imprinting. Trainers begin by taking an object familiar to the dog, say, a blanket, and covering the object with a bit of whatever substance they are trying to train the dog to detect - explosives, drugs, or even a human or animal scent.

They place the blanket with the target scent in a box and wait for the dog to find it. The trainers repeat this process over and over, each time reducing the size of the blanket and increasing the proportion of the scent. In the final step, they remove the blanket entirely, leaving only a patch of the target scent for the dog to detect.

If the dog knows to go after the scent, it is ready for field work.

The team first trained the dogs to detect an ovarian tumor. Then they trained the dog to detect the plasma taken from the tumor. The final step is a bit more complicated. While the team trains the dogs, chemists break down the cancerous ovarian plasma into its individual chemical components.

The researchers are looking for the chemical unique to ovarian cancer, so they run several trials where a dog sniffs each chemical. The one the dog is drawn to will be the one on which they base the design of their sensor.

Doggy disease detectors

Dogs have always enjoyed a reputation for the utility of their sharp sense of smell, especially in the celebrated bloodhound breed, which can follow a scent trail several days old.

Bloodhounds - the dogs most famous for their sniffing abilities - have 230 million olfactory receptor cells. That is 40 times as many as humans have. Their noses are so strong and reliable, their scent-tracking abilities are even admitted as evidence in court cases.

But researchers are now beginning to realize many other canine noses may be more powerful than we previously believed, and that different breeds are well-suited to different types of work.

"The bloodhounds are trailing dogs, man-tracking dogs," study researcher Cindy Otto, of the Penn Working Dog Center, told Business Insider. "They have really good noses. But for a lot of the other work - what we call 'air-scenting', where the dog raises his nose in the air and tries to find the source of a smell, those tend to be the retrievers, the hunting dogs."

Retrievers have been bred to be "trainable," and are often better at working off-leash than the scent-crazy bloodhounds.

Sensing cancer, infection, and seizures

Scientists have already shown dogs to be effective at detecting infections, and in 2004 a team of British scientists found dogs could detect bladder cancer just by sniffing a patient's urine. Dogs can also "predict" seizures in epileptics and potentially life-threatening "superbug" infections.

The field has exploded in the last decade. Now it seems, dogs are being used for everything.

The University of Washington's Center for Conservation Biology trains dogs to keeps tabs on wildlife populations and by sniffing out animal scat. They have even put dogs on boats and trained them to track killer whales by sniffing for their dung.

Biologists are also using them to track invasive or dangerous species, like the pythons that are slithering through Florida.

"Someone was telling me that there are over 180 applications for dog detection," Otto said. "It's so exciting to think about the opportunities."