Human DNA Retrieved From Dogs Might Provide Evidence
by Douglas Ankney
Researchers from Flinders University in Australia published the results of a study involving the work of the Victoria Police Forensic Services Department and Deakin University regarding the collection of human DNA from 20 dogs from separate households. Wearing clean gloves, researchers swabbed samples from the dogs’ chests, tops of their heads, backs, left and right sides, and stomachs. Swabs applied to the left sides were placed below the fur and in contact with the dogs’ skin. All other samples were collected from the surface of the fur.
“[O]f the 120 samples analyzed, the minimum number of contributors could not be determined in 33% of the profiles generated—16 provided no profile and 23 yielded limited profiling information. The majority of these samples with low DNA quantities came from the left side of the dog (14), followed by the chest and stomach (9 samples each) … higher quantities of DNA were recovered from the back, head, and right side of the dogs.” These results led the study’s authors to “theorize that DNA collected by dogs is retained on the surface of the fur rather than being embedded under it.”
Fifteen percent of the samples revealed a single contributor, with the “main human” as “the most common contributor (9 DNA profiles).” In six profiles, an unknown source was the contributor and in three profiles the contributor was another person in the household. Many of the remaining profiles (49) consisted of a two-person mixture; three-person mixtures accounted for seven (7), as did complex mixtures with five or more DNA profiles.
A second part of the study involved a researcher patting and scratching the neck of each participating dog. Twenty DNA profiles were generated, but only 10 contained the DNA of the individual patting the dog. The researchers stated it was reasonable to conclude “that the last person to touch the dog will not always be reflected in the profile.”
Source: forensicmag.com
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