Population genetics for 18 short tandem repeat loci (Canine GenotypesTM Panel 2.1 Kit) of 150 unrelated dogs from three pure-bred groups in Japan

Similar to that in Europe and the United States, the need for forensic DNA identification in dogs is increasing in Japan. As few studies have used commercial genotyping kits, the effectiveness of the Canine GenotypesTM Panel 2.1 Kit for individual DNA identification in dogs bred in Japan was examined. We genotyped 150 unrelated dogs (50 Golden Retrievers, 50 Miniature Dachshunds, and 50 Shiba Inu) at 18 canine short tandem repeat loci by the Kit. The allele frequency, expected heterozygosity, observed heterozygosity, p-value, power of the discriminant, and of exclusion, polymorphic information content, and random matching probability were calculated for each marker. The random matching probability was subsequently estimated to be 4.394×10-22 in the 150 dogs of the three pure-bred groups based on 18 STR loci; 3.257 × 10-16 in the Golden Retriever, 3.933 × 10-18 in the Miniature Dachshund, and 2.107 × 10-18 in the Shiba Inu breeds. In addition, principal component analysis based on genotype data revealed the Golden Retrievers, Miniature Dachshunds, and Shiba Inus separated into three clusters. The results of the genotype analysis showed that the Canine GenotypesTM Panel 2.1 Kit could be useful for identity testing and tool of population study of canines in Japan.

Ribosomal DNA as target for the assessment of DNA degradation of human and canine DNA

The assessment of DNA amount and DNA integrity can support forensic DNA analysis, in particular of problematic traces such as single telogen hairs where STR typing success is often hampered by low amounts and strong degradation of nuclear DNA. Common strategies consist of quantitative polymerase chain reaction (qPCR)-based analysis of the abundance of a short versus a long nuclear amplicon, the latter prone to DNA degradation. To increase sensitivity, commercial qPCR solutions rest on amplification of multi-copy DNA sequences. Here we show that ribosomal DNA (rDNA) sequences are well suited for the same purpose. Because rDNA sequences are present in high copy number in most eukaryotic species, qPCR strategies can easily be adapted to non-human species. In this paper, we establish qPCR-based assays for human or dog DNA, respectively, which allow for sensitive analysis of DNA amounts and DNA degradation. We show that the human system can be applied to DNA of single telogen hairs, where STR typing success correlates with measured amounts and integrity of the DNA. By adapting the system to dog rDNA sequences we found that single telogen dog hairs often displayed less DNA degradation than human telogen hairs, in most cases allowing for successful STR typing. Thus, qPCR-based analysis of rDNA represents a cost-effective, highly sensitive strategy to assess DNA amount and integrity that can be adapted to hairs or other traces from various animal species.

Dog-bite-related attacks: A new forensic approach

Dog attacks today represent a health hazard considering that prevention strategies have not always been successful. The identification of the dog that attacked the victim is necessary, considering the civil or criminal consequences for the animal's owner. An accurate scene analysis must be performed collecting a series of important information. Forensic investigations in dog attacks involve different methods, such as the evaluating of the canine Short Tandem Repeat (STR) typing in saliva traces on wounds or bite mark analysis, however, these techniques cannot always be applied. The effort to find new methods to identify the dog that attacked the victim represents a very interesting field for the forensic community. This study aims to propose an innovative approach, based on the identification of the victim's profile in the dog's mouth, using a buccal swab on the suspected aggressor dog, to find the victim's genetic profile. In addition, a further goal of this study is to determine the persistence time of hexogen DNA in the dog's mouth to define a timeframe for performing this particular technique. For this purpose, ten different dogs were used to aggressively bite a bovine sample (reference sample) to simulate the victim. For each dog two buccal swabs were taken at different time intervals: 30', 45', 60', 90', 120', 150', 180' and 240'. The typing of the swabs provided an interpretable profile after 45' while traces of bovine profile were found until 150' after the dog attack simulation. These results could be improved using the human identification kit, which is more sensitive. In the light of this experimental study, the forensic community should consider using this approach in real casework studies with the aim of collecting new data, validating this technique for forensic use.