Sniffing Out Disease: How Dogs Detect Illness Through Chemistry

Long before laboratories and diagnostic machines existed, detection could begin with something as simple as a sniff. What if the human body, in the earliest stages of disease, quietly releases invisible chemicals that are so subtle that no instrument could detect them, yet unmistakable to one extraordinary friend? A dog.

image source- The Spruce Pets

Dogs are often called a man's best friend and it couldn't be truer. They provide comfort, love and form bonds that are quite impossible to hamper. But, they are so much more than just a good companion- they are extremely amazing smelling machines- possessing a sense of smell so powerful that  they can identify diseases hidden deep within the body before you and I could. But how do they do that? And the answer is quite simple- Chemistry.

Before we dive into the chemistry of disease-smelling, let's learn a little about how their olfactory system works-

Dogs have an incredibly powerful sense of smell- up to 10 million times more sensitive than humans in some specialized breeds. Humans have around 5 million scent receptors, while dogs have between 125 million and 300 million, with breeds like bloodhounds at the higher end. These receptors also cover a much larger area in a dog’s nose (about the size of a pocket handkerchief), compared to a much smaller area in humans (roughly the size of a postage stamp).

Another fascinating difference in humans and dogs’ anatomy are the presence of bony structures called turbinates that are far more intricate than those in humans, allowing them to detect odors up to 100,000 times more accurately.

image source- MDPI

So how do dogs actually detect diseases in humans?

Every human body is constantly carrying out thousands of biochemical reactions. Under normal conditions, these reactions produce a set of chemical byproducts that are released by sweat, urine and our breath. These are known as VOC’s or volatile organic compounds. These are tiny molecules that evaporate into the air.

When the body is affected by a disease like Cancer or diabetes, these biochemical pathways are affected. As a result, the concentration and type of VOCs are also affected and thus changed. In simpler terms, disease conditions create a distinct chemical signature.

image source- LinkedIn ( Ardeshir Bayat MD phD)

Detecting diseases before we can-

Research and real-life world cases have shown that dogs can be trained to detect a variety of diseases, including cancer, hypoglycemia in diabetic patients and even infections. Social service dogs are trained to alert their companions before a dangerous drop in blood glucose levels. This happens due to changes in specific VOC’s that the dog is able to detect. Similarly, cancer cells produce altered metabolic products, which again lead to changes in the VOC’s, hence allowing dogs to analyse and notice them.

What makes this even more intriguing is the fact that dogs can often detect these changes before symptoms become noticeable, making them potential partners in early diagnosis, which could save a life.

image source- Fitzpatrick Referrals

More than an instinct-

It is very easy to assume that dogs have this sense of smell purely through years of evolution or simply instinctual. But it is deeply rooted in chemistry and biology. Dogs are not ‘guessing’ or relying on emotions- they are actually responding to real, measurable chemical changes in the human body.

Their responses are so consistent and accurate, that scientists are coming up with a concept of ‘e-noses’, an intelligent artificial detection system made to mimic their abilities, inspired by our furry friends.

image source- Nature

From one human to another-

There is something very profound about the connection between a human and their dog. A creature that cannot speak our language can still sense when something within us is not right. Perhaps man's best friend is not just a phrase of affection but is a reflection of something deeper- an unspoken partnership where science and companionship meet.

So next time you pet a furry friend, maybe ask them how it feels to be one of nature’s most accurate and consistent machines :)

-By Saanika Kukde (S.Y BPHARM)

-Inspired by my furry friends