Canine physiology and cancer detection

Updated: Sep 3, 2021

In April 1989, Dr. Hywel Williams and Dr. Andres Pembroke from King’s College Hospital, London, reported a case in The Lancet about a Collie-Doberman owner who attended their practice. The dog couldn’t stop sniffing a mole on its owner’s leg, which turned to be cancerous. The mole was removed, thus saving its owner’s life.


Some dogs can detect different types of cancer by smell. We, humans, do not have this quality. How do they do it? What makes dogs different from us?




Dogs have a much more developed olfactory system than humans. Its olfactory capacity is due to the predominance of the olfactory cortex in the brain, formed by the olfactory bulb. The olfactory cortex processes the information that reaches it from the olfactory epithelium. Another difference with humans is the size of this olfactory epithelium, located in the nasal cavity. Dogs can have up to 200-300 million olfactory receptors, while humans have only 5-6 million. This enormous difference is due to tiny variations in the DNA of dogs. These receptors send the information received to the olfactory cortex through sensory neurons. With this considerable development of the olfactory system, they can differentiate many more volatile substances than humans. ("Perros que diagnostican cáncer: ¿cómo lo hacen?", 2020)


Images from: https://www.petpooskiddoo.com/blog/how-is-a-dogs-sense-of-smell-different-from-ours-and-why/



Dogs, therefore, have a highly developed olfactory cortex and neuroepithelium that allows them to detect cancerous volatile substances. Cancer produces physiological changes, generating specific organic compounds. These volatile organic compounds excreted by body fluids will be the ones that will allow dogs to detect cancer. The characteristic substances in a given carcinogen are called biomarkers. It is crucial to know which ones they are to diagnose cancer.


As a result, much of the scientific research in oncology intent to understand different biomarkers of cancer. That would lead to an early-stage metabolites-based cancer test. The Blue Box wants to be able to perform this detection using these biomarkers from a urine sample!



If you want to read more about it, you can consult the following links:

https://pubmed.ncbi.nlm.nih.gov/14659017/

https://pubmed.ncbi.nlm.nih.gov/25264338/

https://phoenixvetcenter.com/blog/214731-how-powerful-is-a-dogs-nose

http://www.seu-roma.it/riviste/clinica_terapeutica/apps/autos.php?id=1570

https://www.medicalnewstoday.com/articles/323620#are-dogs-used-in-cancer-research-and-diagnosis

https://www.infosalus.com/asistencia/noticia-perros-diagnostican-cancer-hacen-20200621075936.html

https://academic.oup.com/jhered/article/99/5/518/2188588?login=true

http://c-doc.org/



Bibliography:


How is a Dog’s Sense of Smell Different from Ours… and Why?. (2017). Retrieved 3 September 2021, from https://www.petpooskiddoo.com/blog/how-is-a-dogs-sense-of-smell-different-from-ours-and-why/


Perros que diagnostican cáncer: ¿cómo lo hacen?. (2020). Retrieved 3 September 2021, from https://www.infosalus.com/asistencia/noticia-perros-diagnostican-cancer-hacen-20200621075936.html







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