Brain Metastases From Solid Cancers in 58 Dogs

: Brain metastases (BM) represent an unmet medical need in human medicine, and they are poorly documented in dogs. The aim of this multi-centre retrospective study was to report the clinical characteristics, primary solid cancer histology, advanced imaging findings, treatment modalities and potential prognostic factors in dogs with presumed BM that occurred either at the time of initial diagnosis or during follow-up. BM diagnosis was established through either imaging studies or histologic examination of specimens obtained during necropsy. A total of 58 client-owned dogs with histologically proven solid cancer and BM were included. Clinicopathologic variables, BM characteristics based on imaging and survival post-BM (SPBM) were recorded. Haemangiosarcoma (53.4%) and carcinoma (27.6%) were the most common primary tumour histotypes, followed by melanoma (12.1%) and undifferentiated sarcoma (6.9%). Synchronous BM and solitary BM occurred in 63.8% and 51.7% of dogs, respectively. The prosencephalus was most commonly affected, with 79% of dogs showing neurologic deficits. Antitumoural or palliative treatment was attempted in a minority of dogs, with no improved outcome. The median SPBM was 3 days (range, 1-255). The 3- and 6-month survival rates were 8.6% and 1.7%, respectively. Dogs with haemangiosarcoma (OR: 7.6; 95% CI, 2.2-25.8; p = 0.001) and those with distant metastases at presentation (OR: 16; 95% CI, 4.2-60.9; p < 0.001) had an increased likelihood of developing synchronous BM. Haemangiosarcoma and carcinoma were the tumours most frequently associated with BM, which were more commonly synchronous and symptomatic, with a high incidence of forebrain localization. The prognosis was poor, regardless of the primary cancer type.