Do dogs smell cancer?

Do Dogs Smell Cancer?

We know they have senses which we don’t, but can dogs smell cancer?

There has been much speculation recently about whether dogs can sense when humans have cancer. The Internet is awash from owners who have gone to their doctors simply because their dog was constantly sniffing or licking a particular area, only to find they are in the early stages of lung, or breast cancer.

It may sound a little crazy, but studies have shown this may well be true.

On an interesting side note, a colleague trained her Border Collie as an assistance dog to help protect her when she has seizures, namely by lying on top of her to prevent her being injured. Her dog can now warn her when she’s about to have a seizure, so before the event, and before she knows it will occur.

How amazing is that?

Back to the question of do dogs smell cancer. Let’s take a look at the research…

Firstly, does cancer smell?

It is suggested that cancer, regardless of where it starts in the body, produces gas with a distinctive odour.

This gas is passed through the body and eventually expelled through the breath. The scientific term for this is volatile organic compounds, or VOCs.

In one study, researchers used specially-trained dogs to detect the smell of prostate cancer in urine samples, with seemingly impressive accuracy. Another study showed some evidence a human nose can be trained to detect the smell of certain types of lung and breast cancers in exhaled breath.

A very interesting study instigated in 2022 at Michigan State University uses locust brains to detect odours from various types human cancer.

“Cancer changes [cellular] metabolism and those changes are reflected in exhaled breath”

Debajit Saha, Assistant Professor of Biomedical Engineering at Michigan State University

This recent study has shown promising results to reinforce our knowledge on cancers having specific odours (or VOCs).

Michigan State University plan to expand on their research into the more complex area of breath samples from human cancer patients, which have far more complex scent signatures than those from the cultured cells of previous experimentation.

Research into whether a dog can smell cancer

A dog’s sense of smell is truly extraordinary.

This is why dogs are used to sniff out drugs (such as in airport security) and find bodies in areas of disaster. So would detecting cancer simply by a sense of smell really be a step too far?

Researchers in the field believe this is not as crazy as it sounds.

In research to determine if dogs can smell cancer, an experiment was carried out using 220 vials filled with the breath from patients with lung cancer and people without. A Labrador, 2 German Shepherds, and an Australian Shepherd were encouraged to sniff each vial.

The dogs correctly identified 71 out of 100 patients with lung cancer and correctly identified 93% of those without the disease.

Although research is rarely conclusive, that study strongly suggests our dogs, can in fact, smell cancer.

An interesting account with a breast cancer patient

Although this account is speculative, I wanted to share it with you as it is one of many personal reports which suggest a dog can smell cancer.

A dog owner noticed how her dog developed a habit of burying his face in her armpit whenever she brushed him. She initially found the behaviour odd and unusual, initially believing her dog had developed a fear of the brush, but over the coming weeks her dog more persistently tried to bury his head in her armpit.

Four months after this bizarre behaviour manifested itself, the owner was diagnosed with breast cancer.

After rigorous treatment she was given the all clear. At this very time her dog completely stopped the unusual behaviour, and the owner feels certain her dog was able to smell the cancer and was trying to warn her.

Now imagine, if we notice our own dogs developing such unusual behaviour, it may be worth considering. Perhaps our dogs can help us detect cancer in the very early stages, making diagnosis and subsequent treatment far more successful?

Can dogs be used to detect illnesses other than cancer with their sense of smell?

Although we’re still in early stages of research, it may not only be cancer which the highly sensitive canine sense of smell can be used to detect.

Some investigation has been conducted to determine if dogs can detect Type 1 Diabetes using sense of smell. The most encouraging part of this research so far, is diseases such as diabetes and cancer can be treated far more successfully in the early stages.

Unfortunately most of the time, as we go about our daily lives, we have a tendency to ignore small yet repetitive symptoms. Perhaps we’re just tired, or perhaps that tweak of persistent discomfort is a pulled muscle or something not worth worrying about.

Although research continues, for many this development between man and dog is merely the next stage in a relationship that has been evolving for hundreds of years.

From the first time man used dogs in order to sniff out vermin or food, to the brave dogs used in the aftermath of 9/11 to search for bodies and survivors, surely the concept of using dogs to smell cancer is just a matter of time?

What are your thoughts? Do dogs smell cancer?


Gina & Maisy

Research papers

Further reading on whether dogs can smell cancer:



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Gina & David

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