Dogs smell tumors: but how do they do it?

Dogs feel tumors: the extraordinary nature of our four legs.

Dogs are not only the best friends of men, but also valuable and irreplaceable contributors to many crime and research activities.

Thanks to their very fine sense of smell, they are able to detect the presence of drugs and other illegal substances, to detect the molecular traces of missing persons, to recover the victims of avalanches or earthquakes, buried under meters of snow or piles of rubble.

But not only! It is now scientifically established that dogs sense tumors and their presence, identifying them even before the advanced diagnostic methods proposed by science.

The first evidence of this incredible olfactory capacity of dogs (the smell of canine odor is up to 100,000 times stronger than ours) dates back to 1989, when the news of a British doctor was published. After seeing his dalmatian sniffing a mole on his wife’s leg after doing the necessary clinical checks, he learned that it was a malignant tumor.

Since then, several scientific studies have been launched within the international medical community to verify the veracity of this intuition. All confirmed, in about thirty years, that the dogs still felt the tumors at the initial stage, so the most sophisticated laboratory tests always manage to identify them.

Among the latest articles on the subject, in early April at the 2019 Experimental Biology Meeting, four Beagles learned to recognize positive blood samples for lung cancer. The results were very accurate, as indicated by the researchers involved in the study: the accuracy of diagnoses was nearly 97%.

Needless to say, this discovery is of paramount importance for early diagnosis and, as a result, opens new perspectives for the possibility of intervening when the disease has just occurred and the chances of recovery and success are greater.

And as if that were not enough, it seems that the reliability of the canine truffle is, in most cases, greater than 90%, sometimes reaching perfection.

Dogs feel tumors: that’s how

How does the dog’s nose detect the presence of cancer cells? Firstly, it should be emphasized that dogs specialized in cancer research are the result of constant and judicious training: it is therefore necessary that the innate predisposition of these animals be encouraged and treated correctly by expert educators, so that they can fully develop their own capabilities. potential.

You only have to see these dogs at work to realize the precise work that awaits them: in the diagnosis of prostate cancer, for example, the urine samples are felt by the dog, treated in such a way as to be able to release volatile and better odorous corpuscles of the dog.

If the animal does not detect any suspicious trace, he remains standing, staring at his trainer; when he detects the presence of the disease, the dog sits or lies on the ground.

With the same method, in addition to prostate cancer, other types of cancer can also be identified: by feeling the breath of a person, the dog is able to feel the presence of breast cancer, the skin, gut and lung, manage not to be misled by other ongoing pathologies against the organ being analyzed, such as COPD (chronic obstructive pulmonary disease) in the case of lung cancer.

Dogs feel tumors: and how is the research going in Italy?

In addition, in our country, sector research has been launched for years, in particular at the Military Veterinary Center in Grosseto, under the direction of Dr. Gianluigi Taverna – Head of the Department of Urology at Humanitas Mater Domini in Castellanza (Varese) – who used the collaboration of two German shepherds, LiĆ¹ and Zoe, previously anti-mine dogs, trained in the less bloody search for prostate cancer cells.

Here are his statements: “Despite the efforts made, we do not know until now what is the specific pool of molecules that constitutes the smell of the tumor, the only thing known is that it is specific to cancer, that is to say that each type of tumor has its characteristic odor.However, we are still in the research phase and the dog can not currently be used in clinical routine.


In addition to confirming the dogs’ incredible ability, the importance of these studies, the team’s director pointed out, is that they have clearly shown researchers that tumor molecules have a distinctive odor that distinguishes them. thanks to what The smell of the dog can feel the presence of the disease.

The cells that make up cancer have a specific metabolism that generates a set of components of nitrogen and hydrocarbons, so as to produce characteristic emanations that only the nose of the dog can feel.

Although there were many more studies and meta-analyzes confirming the ability and accuracy of dogs to diagnose tumors, it would still be difficult for these animals to represent the future of the diagnosis. Even if they can have a bad day, they are not machines. However, research on their work could help develop tools that replicate their capabilities, such as the electronic nose, a biomimetic system that seeks to replicate the olfactory tract.

The new challenge of science is now to identify the cancer molecules that the dog feels, in order to create a new diagnostic tool able to recognize their smell, a kind of “electronic truffle”.