Techniques We Use
For a sample that is taken from a sealed and documented can or package of pet food, total DNA is extracted from the contents, and a fragment of the mitochondrial Cytochrome B gene is amplified via the Polymerase Chain Reaction (PCR) using several sets of forward and reverse primers, one set specific for dog DNA, the other for cat.
Each PCR primer set is validated for high level of specificity. In addition, a set of PCR primers that amplify a portion of a universally conserved Histone 4 sequence is used as a positive control to validate the quality of total DNA extracted from each pet food sample.
Detection of a PCR product on an agarose gel with a primer set specific to a particular organism indicates that this organism’s DNA is present in the pet food sample. Absence of detectable PCR product indicates that a particular organism’s DNA is not present in that sample above the detection limit of the assay (at least one part per 1000).