Epidemiology of Splenic Lesions in Dogs Undergoing Splenectomy—Pathological Characterization and Risk Factors

Splenic lesions are common in dogs and can have important clinical implications due to the risk of rupture causing life-threatening hemorrhage, or, for neoplastic lesions, potential metastatic spread. This retrospective study analyzed 682 canine spleen samples submitted to the Regional Canine Cancer Registry in Umbria, Italy, between 2014 and 2023, aiming to characterize lesion types and explore associations with demographic factors and clinical outcomes. Lesions were classified as neoplastic or non-neoplastic. Non-neoplastic lesions were predominant (54.3%), mainly nodular hyperplasia, hematoma, and congestion, while neoplastic lesions accounted for 45.7%, with hemangiosarcoma (HSA) being the most frequent neoplasm (54.5%), followed by other sarcomas, lymphomas, and rare tumors. The mean age at diagnosis was 10.4 years, and medium-sized dogs living in urban areas were most affected. No significant differences in lesion type were observed between sexes or between purebred and mixed-breed dogs, although purebreds were more represented overall. HSA risk varied by size, sex, and breed, with large dogs and certain pure breeds showing elevated risk. Survival analysis revealed markedly reduced outcomes for dogs with HSA. These findings emphasize the utility of histopathologic diagnosis in guiding clinical management and provide insight into the epidemiology and prognosis of splenic lesions in dogs.