Searching for human remains and other body fluid is unlike any other dog detection work as the target scent is constantly evolving requiring regular research.
In the main, other scent targets such as narcotics or explosives do not change over relative short periods of time. Therefore it is important to understand these changes and to be able to train a dog to recognise the various stages of decomposition.
Over many years I have worked in partnership with various universities and professional bodies (pardon the pun!) to identify how subtle changes can affect a dog’s performance. Various studies have been undertaken in clinical conditions and these have identified not only the dog’s inherent strengths but also, and more importantly, its weaknesses.
These studies have includes : Age of Bones; Quantity of Blood and Timescales; Stages of Decomposition; Other Meat Scents; Environmental Conditions i.e. soil types.
CANCER DETECTION DOGS
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Br J Dermatol. 2016 Nov;175(5):1020-1029. doi: 10.1111/bjd.14887. Epub 2016 Sep 11.
Invasive melanoma in vivo can be distinguished from basal cell carcinoma, benign naevi and healthy skin by canine olfaction: a proof-of-principle study of differential volatile organic compound emission.
Willis CM1, Britton LE2, Swindells MA3, Jones EM4, Kemp AE2, Muirhead NL2, Gul A2, Matin RN5, Knutsson L6, Ali M2.
Volatile organic compounds (VOCs) are continuously released by the body during normal metabolic processes, but their profiles change in the presence of cancer. Robust evidence that invasive melanoma in vivo emits a characteristic VOC signature is lacking.
To conduct a canine olfactory, proof-of-principle study to investigate whether VOCs from invasive melanoma are distinguishable from those of basal cell carcinoma (BCC), benign naevi and healthy skin in vivo.
After a 13-month training period, the dog’s ability to discriminate melanoma was evaluated in 20 double-blind tests, each requiring selection of one melanoma sample from nine controls (three each of BCC, naevi and healthy skin; all samples new to the dog).
The dog correctly selected the melanoma sample on nine (45%) occasions (95% confidence interval 0·23-0·68) vs. 10% expected by chance alone. A one-sided exact binomial test gave a P-value of < 0·01, supporting the hypothesis that samples were not chosen at random but that some degree of VOC signal from the melanoma samples significantly increased the probability of their detection. Use of a discrete-choice model confirmed melanoma as the most influential of the recorded medical/personal covariates in determining the dog’s choice of sample. Accuracy rates based on familiar samples during training were not a reliable indicator of the dog’s ability to distinguish melanoma, when confronted with new, unknown samples.
Invasive melanoma in vivo releases odorous VOCs distinct from those of BCC, benign naevi and healthy skin, adding to the evidence that the volatile metabolome of melanoma contains diagnostically useful biomarkers.
© 2016 British Association of Dermatologists.
PMID: 27454583 DOI: 10.1111/bjd.14887