Doxorubicin–Cyclophosphamide Protocol in Dogs with Splenic Haemangiosarcoma and Haemoabdomen: A Retrospective Case Series

Abstract

Simple Summary Many dogs develop a fast-growing cancer of the spleen that can rupture and cause internal bleeding in the abdomen. This emergency often requires the spleen to be removed, but it is unclear which follow-up treatments help dogs to live longer. We reviewed the medical records of 21 dogs that underwent splenectomy for this cancer and received a planned course of two commonly used chemotherapy drugs (doxorubicin and cyclophosphamide). We investigated how long the dogs survived, how well they tolerated the treatment and whether completing more of the planned cycles made a difference. The median survival time after surgery was approximately three months (92 days). Dogs that completed three or more cycles survived for around 200 days, whereas those that received fewer cycles survived for around 55 days. Side effects were generally mild and serious problems were rare. Some dogs also received continuous, very-low-dose daily chemotherapy later on, and they lived longer. However, the numbers were too small to draw firm conclusions. No single test result at diagnosis predicted outcome. These findings suggest that a structured, well-tolerated chemotherapy plan following surgery could help some dogs with this emergency cancer to live longer. Further research is needed to confirm the most effective approach. Abstract This retrospective case series describes 21 dogs with stage II splenic haemangiosarcoma (HSA) and spontaneous haemoabdomen treated with splenectomy followed by a doxorubicin–cyclophosphamide protocol. Median overall survival was 92 days, with longer survival observed in dogs completing three or more chemotherapy cycles. The regimen was well tolerated, with low haematological and gastrointestinal toxicity. Maintenance metronomic chemotherapy was administered in a small subset, and it was associated with prolonged survival. While the sample size is modest, the homogeneous and clinically specific cohort provides hypothesis-generating observations on feasibility, tolerability, and time-aware associations that warrant cautious interpretation and prospective confirmation. No clinical or laboratory variable at diagnosis was independently associated with outcome. While limited by retrospective design and small sample size, this study provides focused data on a specific clinical presentation and supports the feasibility of structured adjuvant treatment in dogs with splenic HSA and haemoabdomen