Canine Splenic Hemangiosarcoma: Biological Behavior, Clinical Challenges and Therapeutic Limitations

Canine splenic hemangiosarcoma is a highly malignant vascular neoplasm and is among the most frequent and clinically relevant splenic tumors in dogs. Its biological behavior is characterized by rapid growth, marked invasiveness, and early metastatic dissemination, contributing to the poor prognosis commonly observed in affected animals. Clinically, splenic hemangiosarcoma often remains subclinical until acute presentation due to splenic rupture and hemoperitoneum, thereby substantially limiting opportunities for early diagnosis and timely therapeutic intervention. Despite advances in diagnostic imaging, surgical techniques, and the use of adjuvant chemotherapy, the impact of current therapeutic approaches on long-term survival remains limited. Splenectomy is primarily palliative for hemorrhage control, and adjuvant doxorubicin-based chemotherapy yields only modest improvements in median survival; alternative approaches (metronomic chemotherapy, immunotherapy, and targeted therapies) have not demonstrated consistent clinical benefit. This review summarizes the biological and pathophysiological features of canine splenic hemangiosarcoma, discusses the main clinical challenges associated with its diagnosis and staging, and critically reviews current therapeutic approaches and their limitations. By integrating biological behavior with clinical and therapeutic evidence, this article highlights the reasons why prognosis remains poor and underscores the need for more effective strategies to improve clinical outcomes in dogs with splenic hemangiosarcoma.