Clinical and pathological characterization and prognostic implications of brain metastases in dogs

Canine cancer pathology exhibits striking parallels with human malignancies regarding tissue structure, biological characteristics, genetic modifications, and therapeutic responses, establishing dogs as valuable subjects for comparative cancer research. Brain metastases (BMs) represent an unmet medical need in human medicine, and they are poorly documented in dogs. This thesis aims to provide an integrated overview of the understanding and management of brain metastases in human and veterinary neuro-oncology, with the goal of inspiring future progress in diagnostic and therapeutic approaches for dogs. Two parts composed this thesis. Part I provides an in-depth examination of the fundamental aspects of brain tumors in both human and canine species. It begins with a comprehensive classification framework, distinguishing between primary and metastatic neoplasms of the central nervous system. Subsequently, it delineates the current understanding of the pathogenetic mechanisms, clinical features, state-of-the-art diagnostic imaging modalities, therapeutic strategies, and prognostic factors associated with metastatic brain tumors in both human and veterinary medicine. Part II described a retrospective study with the primary aim to report the clinical characteristics, primary solid cancer histology, advanced imaging findings, treatment modalities, and potential prognostic factors in dogs with presumed BMs that occurred either at the time of initial diagnosis or during follow-up. specimens obtained during necropsy. Regarding the second part, a total of 58 client-owned dogs with histologically proven solid cancer and BM were included. Haemangiosarcoma (53.4%) and carcinoma (27.6%) were the most common primary tumour histotypes. The prosencephalon was most commonly affected, with 79% of dogs showing neurologic deficits. The median survival post-BM was 3 days (range, 1-255) and the 3- and 6-month survival rates were 8.6% and 1.7%, respectively. Dogs with haemangiosarcoma and those with distant metastases at presentation had an increased likelihood of developing synchronous BM. The prognosis was poor, regardless of the primary cancer type.