DOG BITE-RELATED ACCIDENTS: A NEW FORENSIC APPROACH

The alarming statistics reported around the world have shown that dog attacks today represent a health hazard where prevention strategies have not always been successful 1,2. Most of the dogs involved in these events are known to the victim or belong to him. From our study we found 19 dog bite-related fatalities in Italy from 2009 to 2016 (2,37 cases for year) 3; these data are sharply increased in relationship with previous study that describes 32 dog bite-related fatalities between 1984 to 20094 with a frequency of 1,28 cases for year. A scientific inclusion/exclusion of the involved dog is possible and also recommended because of the possible consequences for the animal’s owner that could have civil consequences or criminal consequences in the most serious cases. Since dog bite mark analysis should involve different forensic professionals such as pathologists, odontologists, veterinarians, biologists, and also police investigators, a review focused on this type of evidence from a multidisciplinary point of view is presented. To the best of our knowledge, there are different approaches for identification of offending dog when a human attack occurs. Forensic investigations in dog attacks usually involve the examination of bite marks and toothprints, the dog’s stomach and pathological methods. For the identification of the offending dog the best approach is to evaluate the canine STR typing into saliva traces on dog bite marks. Generally, it is possible to obtain a canine-specific STR profile from the dog’s saliva left on the wound area, even when high background of human DNA was present (blood). This approach is often a problem because the surface of the wounds may have been treated, for example by first aid workers, removing the canine cells. This approach causes less success in obtaining useful STR results, before that the medico-legal techniques are applied. Furthermore, the dogs appear more frequently in human social life, so it is no rare that the canine DNA is present on hands, arms, legs or foot of the people. A new forensic approach was described for offending dog identification starting from dog's buccal swabs: the target is the identification of human profile starting from this sample. The further goal of this paper was to determine the latency time of this biological trace in the dog's mouth. In this work, 10 different races of dogs were used that bite a beef meat sample, previously typed (internal control profile). At different times (30’, 45’, 60’, 90’, 120’, 150’, 180’, 240’), 2 dog buccal swabs were done (a swab for each dental arch). 160 samples were collected. Subsequently DNA was extract and bovine genotyping kit was used. We found in all samples a complete profile of our internal control until 45 minutes and a partial profile until 150 minutes. These data are very important to confirm the possibility of approaching with buccal swabs to reach the identification of offending dog. The human STRs typing kits are much more specific and sensitive compared with cattle kit, so we can supposed that a complete human STR profile could be obtained from the dog buccal swab, after aggression, at least to 150 minutes. This time is usually enough for the medico-legal team arrive. This study may offer a model that could be always applied for identification of offending dogs; furthermore, dog-bite related accidents can provide concrete cases even fatal, making it possible to develop, refine or validate medico-legal techniques.