Comparative habitat-associated patterns of pathomorphological changes in the internal organs of the European brown...

The European brown hare (Lepus europaeus Pall.) is an ecologically significant game species widely used as a bioindicator of environmental conditions because of its sensitivity to habitat changes and human activities. Pathomorphological changes in internal organs offer valuable insights into the health of wildlife populations and may indicate exposure to various environmental stressors. However, research that evaluates multiple organ systems simultaneously in relation to habitat type within the same spatiotemporal context remains limited. Therefore, this study aimed to compare the frequency and distribution of pathomorphological changes in the liver, lungs, spleen, and kidneys of European brown hares from agricultural and periurban or industrial hunting areas in central Serbia during the same hunting season. The study also sought to identify potential habitat-related patterns in organ alterations.

The study was carried out during the 2017/2018 hunting season on 74 European brown hares collected from four hunting grounds in central Serbia, classified as agricultural or periurban/industrial based on land use. Macroscopic and histopathological examinations included the liver (n = 74), lungs (n = 73), spleen (n = 61), and kidneys (n = 65). Tissue samples were fixed in 10% neutral buffered formalin, processed with routine paraffin techniques, sectioned at 3-5 µm, and stained with hematoxylin and eosin. The frequency of pathological changes was analyzed using Pearson's chi-square test and Fisher's exact test, with statistical significance set at p < 0.05. Odds ratios with 95% confidence intervals were calculated to evaluate the association between lesion presence and hunting ground type.

Significant habitat-related differences were observed in several organs. Dystrophic liver changes were more common in hares from agricultural hunting grounds (OR = 0.33; p = 0.026). In the lungs, bronchiolitis (OR = 0.32; p = 0.025) and emphysema (OR = 0.10; p = 0.010) occurred more frequently in hares from periurban or industrial areas. In the spleen, lymphoid hyperplasia (OR = 0.22; p = 0.008) and splenomegaly (OR = 0.06; p = 0.0001) were significantly more prevalent in agricultural habitats. No statistically significant link between hunting ground type and kidney lesions was found.

Distinct habitat-related patterns of pathomorphological changes were observed in the European brown hare, with liver and spleen abnormalities mainly in agricultural areas and lung lesions in periurban or industrial regions. These findings suggest that organ-based pathology can be a useful additional tool for wildlife health monitoring and may offer early signs of adverse environmental conditions without establishing direct cause-and-effect relationships.