Abstract
Background:
Canine hemangiosarcoma (HSA), which originates from endothelial cells, is one of the most common malignant neoplasms that frequently develop metastatic lesions. Although anthracycline-based HSA treatment strategies have been widely investigated, reliable therapy for dogs with clinically advanced-stage HSA (stage 3 HSA) has not been established yet. Recently, several studies have demonstrated that propranolol, a beta-adrenergic receptor antagonist, exhibits anti-tumor effects against tumors originating from vascular endothelial cells, indicating the possibility that propranolol is a candidate adjunctive agent for anthracycline-based therapy in dogs with stage 3 HSA. This study aimed to evaluate the clinically efficacy and adverse events of anthracycline and propranolol combination in stage 3 HSA-affected dogs.
Case Description:
We retrospectively investigated 5 dogs diagnosed with stage 3 HSA which were administered with both anthracycline and propranolol during the same period between January 2020 and August 2021. Clinical benefit was observed in 4 of 5 HSA dogs (1 of complete response [CR], 1 of partial response [PR] and 2 of stable disease [SD]) with gross metastatic lesions by anthracycline and propranolol combination. Notably, some or all of the metastatic lesions were reduced in 2 cases. In all 5 dogs administered with anthracycline and propranolol combination, no serious and irreversible adverse effects were observed.
Conclusion:
Our findings demonstrate the efficacy and safety of anthracycline and propranolol combination in stage 3 HSA-affected dogs. Further studies are needed to establish treatment protocols based on anthracycline and propranolol combination for dogs with advanced HSA.

Key words: Hemangiosarcoma, Stage 3, Dog, Anthracycline, Propranolol