Hemangiosarcoma associated with a Pasteurella multocida infection in a near threatened cinereous vulture (Aegypius monachus): insights into avian pathology and implications for conservation

Background: Cinereous vultures (Aegypius monachus) are Near Threatened (NT) scavenger species vital to ecosystem health, yet little is known about neoplastic diseases affecting them. Hemangiosarcoma (HSA), a malignant tumor of vascular endothelial origin, is rarely reported in avian species, and its interaction with opportunistic infections remains unexplored. Case presentation: We report the first case of pulmonary hemangiosarcoma concurrent with Pasteurella multocida infection in a cinereous vulture. The adult female bird presented with severe neurological and systemic symptoms, including opisthotonos and emaciation. Diagnostic evaluation involved imaging (CT and MRI), serum chemistry, histopathology, immunohistochemistry, and bacterial culture. Gross pathology revealed a large pulmonary tumor, confirmed as HSA via CD31 immunoreactivity. Concurrent infection with P. multocida subsp. septica was identified by culture and 16 S rRNA sequencing, with virulence genes (pfhA, hgbB) detected via multiplex PCR. Neurological signs were attributed to septic encephalopathy. Conclusions: This case illustrates the complex interplay between neoplasia and bacterial infection in avian species and underscores the importance of multidisciplinary diagnostics in wildlife disease surveillance. Based on the clinical course and pathological findings, the most likely cause of death was acute septicemia with septic encephalopathy secondary to pulmonary hemangiosarcoma and concurrent Pasteurella multocida infection. Enhanced awareness of neoplastic conditions in Near Threatened scavenger birds is essential for effective conservation and rehabilitation strategies.