Canine Olfactory Detection: for medical and forensic purposes

Evita Apalaki

Apart from their great company, the extra sensitive olfactory ability of dogs has been an important help for civilian and military purposes for centuries now. Dogs have 40 times greater smell capacity than an average human does. Up to 300 million olfactory receptors located in their noses are activated by external odors. The signal is finally transmitted to the part of the brain responsible for the analysis and identification of smells, which is 40 times stronger compared to humans. The inhaled air is being separated into two different airpaths, one for respiration and one for olfaction. This enhances the capacity of the canines to be able to smell and identify a vast number of chemical compounds, even discerning the difference between molecules with small structural differences. 

This extraordinary ability of dogs was not left unexploited by humans. The Canis familiaris has been trained to identify specific odors amongst a vast majority of others and provide important information in military and forensic research. For centuries, dogs have helped with the recognition of gangrene gas on the battlefield and diabetic ketoacidosis in emergency rooms. Nowadays they are trained to be involved in the detection of more than 30 different test groups for medical and military purposes. From plants to bacteria and insects, they also aid investigations that involve narcotics and explosives. Furthermore, dogs can also smell with high efficiency the signs of decomposition. The commonly known “Cadaver dogs”can locate dead bodies, biological tissues, bones and burial sites with 95% of accuracy, even if the remains are 8-10 meters underground.

The most impressive part is that there are signs that this canine ability can distinguish healthy from sick people. Dogs can “sniff” different kinds of diseases, like cancers, diabetes and inflammations. There are reports dating back to 1989 supporting the idea that dogs can help with the medical detection of diseases, but there was not extensive research done at that time. Even if it is still under investigation, contemporary knowledge indicates that those animals can successfully identify signs of virus, bacteria and other health irregularities that human bodies carry. The phenomenon can be explained by medical facts. In cancer or other health diseases and infections, the function of the metabolism changes. The cells in the affected tissues produce altered compounds, depending on the nature and the seriousness of the condition. Most of these products are Volatile Compounds (VC) that are present in biological material and secretions, like blood, sweat, saliva, urine, feces and breath.  After special training, dogs can learn how to distinguish such compounds from a pool of many others, thus leading to the detection of sick people. 

The early diagnosis of serious diseases is a very important process in contemporary medical science. Especially health irregularities that cannot be fully cured yet, such as several cancer cases, which need to be detected at an early stage in order to find a more effective treatment. Ongoing experiments indicate that dogs can contribute to the earlier diagnosis of malignancies through identification of specific odors coming from bodies that suffer from diseases. It is said that each medical condition can create a specific odor, which results from the combination of volatile compounds, like benzene and alkanes. Those odors reflect the medical condition of a person, known as the “odor fingerprint.” Scientists have tried to mimic dogs’ charisma to sniff and identify a disease by making an electronic device that functions in the same manner. With the “electronic nose” the user can identify the composition of the exhaled air or other samples from a human body and, if possible, relate it to a disease. 

The sensitive olfactory ability of dogs has proven to be very helpful in the forensic and medical sciences so far. There is great potential for diagnosing a disease in an early stage through a quick, painless and non-invasive process. However, there are some points of major importance that need to be taken into consideration. The accuracy of the detection of the odors doesn’t depend only on the canine’s olfactory capability, but also on the ability of the trainer to recognize and identify the signs from the dog. The sniffing duration and the level of nervousness of the dog during the process are key points that need to be observed. False negative interpretations of behaviors can be eliminated through better bonding between the dog and the handler. The olfactory ability of the canines seems to be a very promising diagnostic method for the detection of biomarkers and odor fingerprints. Dogs express in a variety of ways how loyal and what good friends they can be for humans.   

Sources: Medical News Today