PRELIMINARY INVESTIGATIONS IN FORENSIC PATHOLOGY OF EASTERN GRAY SQUIRREL'S (Sciurus carolinensis) SKIN LESIONS

Forensic pathology is a discipline that focuses on determining the cause of death by examining a corpse. One of the most challenging tasks of forensic pathology is to determine the post-mortem interval (PMI), i.e. the time that passes from the death of the animal to the finding of the corpse. Various methods have been proposed to establish the PMI, including liver temperature, gastric emptying time, rigor mortis, etc. However, none of these methods is applicable to each scenario. To date only few studies, especially in veterinary medicine, relate to the post-mortem changes in the skin. In a previous study performed at the Department of Veterinary Sciences of the University of Turin, numerous fungal elements were observed in the skin of healthy Eastern gray squirrels (Sciurus carolinensis). Aims of this study were to: • evaluate post-mortem skin changes in Eastern gray squirrels, with particular attention to fungal growth, bacterial colonization and cell conservation status; • determine if in the previous study the fungal skin colonization started intra-vitam or postmortem; • clarify if (and how) a post-mortem growth of fungi is possible. The gross and histopathological alterations of the skin of 5 Eastern gray squirrels (3 males and 2 females), obtained from a regional containment program, were evaluated. The corpses were storage at constant temperature (26°C) and humidity (80%) and skin was sampled at 5, 51 and 111 hours after death in six different body areas (underarms base of the nape, base of the tail). For each sample, hematoxylin-eosin, PAS and Grocott histological stainings were performed, and possible alterations were evaluated by two independent double blind operators, using a semi-quantitative scale from 0 to 3 for the following parameters: presence of crusts, inflammatory infiltration, presence of hyphae, fungal elements and bacteria, and cell conservation status. The cells appeared to be preserved, apart from some slight alterations, up to 51 hours, while at 111 hours cell degeneration and absence of nuclei were detected. Histological examination showed the growth of hyphae and fungal elements at 111 hours after death as well as an increase of bacterial colonies, as already reported in literature [1]. The hyphae may belong to soil keratinophilic fungi, which are commensal organisms in healthy individuals and are not normally able to cause disease in living organism [2]. Then, according to our results, we can state that the fungi (already found in our previous study) colonized the animal’s skin intravitam; this finding raises interesting clinical considerations, as for the first time fungal elements were found in the stratum corneum of the skin in asymptomatic animals. The detection of skin changes, including an effective fungal growth, after 111 hours from the death can be considered an important finding in forensic pathology, and may have practical implications in determining the PMI. [1] Janaway et al. 2009. In Microbiology and Aging. Springer Science, 2008. [2] Deshmukh SK, Verekar SA. Incidence of keratinophilic fungi from the soils of Vedanthangal Water Bird Sanctuary (India), Mycoses, 54:487-90, 2011.