by Cesare Pecarisi
They perceive glycosaminoglycans, the presence of which in blood and urine, according to researchers at Karolinska Institutet, has a 95% specificity for various types of tumors, including breast, prostate and lung
It has long been known that dogs, particularly Labradors, Newfoundlands, Dalmatians and St. Bernards, can smell diseases, particularly certain tumors (such as breast, prostate or lung tumours) before they produce clinical manifestations. But what do they smell? The answer may coincidentally come from a study published in PNAS by Swedish researchers from Karolinska Institutet led by Sinisa Bratulic on 1,260 subjects: They were looking for a non-invasive method for early detection of tumors from urine, the smell of which allows dogs to not only the presence of tumours, but also the presence of diabetes or the onset of an epileptic, migraine or narcoleptic attack a few hours in advance.
glycosaminoglycans
Swedish researchers have managed to identify 14 different types of tumors based on the concentration of glycosaminoglycans (abbreviated GAG), which are normally part of the extracellular matrix of tendons, to which together with elastin and collagen they give elastic properties that allow stretching . These polysaccharides are prematurely modified by tumors by breaking them down in the blood and urine: by looking for them in plasma as well, the Swedish researchers were able to find a test sensitivity of between 41.6 and 62.3% and a specificity of 95% for tumors in the first test phase, a diagnostic accuracy twice that of any other method available today. What smell do glycosaminoglycans have to have in order for dogs to smell them? Apparently they are odorless to us, but not to our four-legged friends, whose olfactory sense has 150-300 million cells depending on breed, while humans have only five with a brain area for detecting smells of about five square centimeters compared to a dog’s 150-size.
Another brain
Last summer, a study by researchers from the Universities of New York and San Francisco, led by Philippa Johnson, and published in the Journal of Neuroscience, discovered a network of five neural connections we lack that stretch from the dog’s olfactory bulb directly to other areas stretches the brain. : occipital lobes, cortical spinal tract, limbic system, piriformis lobes and entorhinal cortex. He explains how dogs can integrate olfactory stimuli into their cognitive functions so that smells become an open book for them.
Not just cancer
There are now many reports suggesting that dogs can smell certain diseases, such as diabetes or changes in blood sugar. On the other hand, the famous 17th-century physician Thomas Willis used taste instead of smell because when he sampled the urine of diabetics, he was the first to discover that their urine was exceptionally sweet, as if it contained sugar or honey. However, dogs can smell blood sugar changes even before the onset of diabetes and alert their owners with abnormal proximity-seeking behaviors, as if they know they need to be tended to.
sweat and breathe
The most surprising thing is that they also anticipate the attacks of diseases such as migraines, epilepsy or narcolepsy, for which there are still no clinical tests. Apparently, in this case, instead of urinating, dogs perceive the increase in stress markers triggered by the arrival of attacks in sweat and breath, as found in a recent Irish study published in PLOSone.
positive reinforcement
Their ability to smell odors imperceptible to us makes them valuable in any situation where the nose is essential, such as searching for survivors of natural disasters or anti-drug operations where the police can use their skills Help from dogs multiplies educators and veterinarians with the so-called positive reinforcement method, which rewards recognizing a specific smell.
January 17, 2023 (change January 17, 2023 | 16:54)
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