This retrospective study of 30 dogs explores whether doxorubicin can serve as a rescue therapy for dogs presenting with acute hemorrhage from suspected hemangiosarcoma when surgery isn’t feasible, and the results suggest it can.
All 30 dogs presented with active intracavitary or pulmonary bleeding and lesions consistent with hemangiosarcoma, though only one case was histopathologically confirmed. Most had multiple sites of disease, with the liver and spleen most commonly involved. Cardiac hemangiosarcoma was excluded by study design, as were isolated splenic or hepatic masses without metastasis. Every patient received doxorubicin as primary therapy rather than surgery.
Overall median survival was 82 days, a meaningful margin compared to the 12-day MST previously reported for untreated presumptive cardiac hemangiosarcoma. Two factors stood out as significant: weight and whether a second agent was added. Dogs over 15 kg survived a median of 126 days versus 54 days for smaller dogs, a difference likely influenced by dosing conventions: doxorubicin is calculated differently above and below 15 kg, and smaller patients may be underdosed as a result. Dogs who received an additional agent (most commonly rapamycin) reached a median of 156 days, compared to 73 days with doxorubicin alone.
Beyond survival, 16 of 20 reassessed patients showed at least some reduction in effusion following treatment, and time to re-effusion was substantially longer in larger dogs (85 days vs. 0.1 days). One patient received radiation therapy between doxorubicin doses and survived 145 days; one received an autologous tumor vaccine. Rapamycin, an mTOR inhibitor, appeared in five of the eight patients who received a second agent. There is no prior hemangiosarcoma-specific data on rapamycin, but its anti-proliferative properties in other cancers are documented.
The limitations are worth noting: it’s a small retrospective cohort, staging was inconsistent, and the majority of diagnoses were presumptive. But the central finding that doxorubicin can offer meaningful time beyond the surgery-or-euthanasia binary is clinically relevant and worth further study.
