The “olfactory fingerprint”: can diagnostics be improved by combining canine and digital noses?

Abstract

<jats:title>Abstract</jats:title><jats:p>A sniffer (detecting) dog is conventionally defined as an animal trained to use its olfactory perceptions for detecting a vast array of substances, mostly volatile organic compounds (VOCs), including those exceptionally or exclusively generated in humans bearing specific pathologies. Such an extraordinary sniffing performance translates into the capability of detecting compounds close to the femtomolar level, with performance comparable to that of current mass spectrometry-based laboratory applications. Not only can dogs accurately detect “abnormal volatilomes” reflecting something wrong happening to their owners, but they can also perceive visual, vocal and behavioral signals, which altogether would contribute to raise their alertness. Although it seems reasonable to conclude that sniffer dogs could never be considered absolutely “diagnostic” for a given disorder, several lines of evidence attest that they may serve as efficient screening aids for many pathological conditions affecting their human companions. Favorable results have been obtained in trials on cancers, diabetes, seizures, narcolepsy and migraine, whilst interesting evidence is also emerging on the capability of early and accurately identifying patients with infectious diseases. This would lead the way to proposing an “olfactory fingerprint” loop, where evidence that dogs can identify the presence of human pathologies provides implicit proof of the existence of disease-specific volatilomes, which can be studied for developing laboratory techniques. Contextually, the evidence that specific pathologies are associated with abnormal VOC generation may serve as reliable basis for training dogs to detect these compounds, even (or especially) in patients at an asymptomatic phase.</jats:p>

Sensory Transduction in Photoreceptors and Olfactory Sensory Neurons: Common Features and Distinct Characteristics

“…A larger number of OSNs, particularly in species relying heavily on their sense of smell, may enhance further the detection of odorants. For instance, the human olfactory epithelium covers ∼3-4 cm 2 and contains approximately 5-6 million OSNs while in the case of dogs, the area of the olfactory epithelium is 18-150 cm 2 and contains 150-300 million OSNs (Lippi and Heaney, 2020).…”

Use of Detection Dogs in Forensic Investigations: The Italian Scenario

“…Dogs can be also used in pet therapy. Recent studies are focused on their ability to detect pathological conditions such as cancers, diabetes, seizures, narcolepsy and migraine [38], as well as in case of a global health emergency such as the current COVID-19 pandemic [39]. For this reason, it is important to highlight that science can offer fundamental contribution to the K-9 field, in particular in forensic odorology where scientific evidence provided by dogs, further supported by traditional investigation techniques, can contribute to the successful outcome of a criminal proceeding.…”

The role of bio-detection dogs in the prevention and diagnosis of infectious diseases: A systematic review

“…Bacterial Diseases: For the detection of bacterial diseases, dogs are expected to identify volatile metabolites, which are bacteria-specific fingerprints and produced during microbial replication (33). Two different training approaches have been conducted in the studies on the detection of bacterial infections by dogs.…”

“…Although these specific VOCs can be identified by methods such as gas chromatography-mass spectrometry (GC-MS), potential use of this method as a diagnostic tool is limited because it is time consuming, expensive and it requires qualified operators (42). It has been reported that dogs' exceptional sniffing performance is comparable to the current mass spectrometry-based laboratory applications and is capable of detecting compounds close to the femtomolar level (33,62).…”