Diagnostic dogs were first reported back in 1989 and further studies have shown that dogs can detect some cancers such as those of the skin, bladder, bowel and breast. Following the previous story - Bowel Cancer detected by sniffer dog - which described a study conducted in Japan, a similar study has now been conducted in Germany to see if sniffer dogs can detect lung cancer. The claim is that sniffer dogs can be used to reliably detect lung cancer, according to the German researchers. In the paper published in the European Respiratory Journal, the authors found that trained dogs could detect a tumour in 71% of patients. Tumours produce "volatile chemicals" in sufficient amounts for a dog to detect. The study included four dogs - two German shepherds, an Australian shepherd and a Labrador.
Will dogs replace diagnostic pathologists?
The researchers also showed that the dogs were not confused by chemicals associated with chronic obstructive pulmonary disease (COPD) or smoking, which makes them more reliable than many other, more traditional diagnostic tests. However, the smelly chemical(s) that is evidently associated with the tumour has not been identified yet by humans. So the question is; just because Fido cannot explain the precise biochemical structure of what he is detecting, does that make him a lesser diagnostician?
Dr Thorsten Walles, the report's author from Schillerhoehe Hospital, said: "In the breath of patients with lung cancer, there are likely to be different chemicals to normal breath samples and the dogs' keen sense of smell can detect this difference at an early stage of the disease. Our results confirm the presence of a stable marker for lung cancer. This is a big step forward."
In an embarrassing attempt to catch up, human researchers are working on "electronic noses" which would be able to detect the same chemical as the dog. But this chemical or combination of smells has not yet been identified, and this is a fundamental problem. Dr Laura McCallum from Cancer Research UK, admits: ""It would be extremely difficult to use dogs in the clinic, further research is being carried out to learn more about these molecules that are released from tumours and whether devices such as 'electronic noses' could help sniff them out."
