Clinical Remission of an Unresectable Presumptive Haemangiosarcoma in a Dog Treated With Toceranib, Piroxicam, and Propranolol: A Case Report.

Haemangiosarcoma (HSA) is a highly aggressive vascular tumour in dogs, characterised by rapid growth, early metastasis, and poor prognosis despite conventional treatment with surgery and doxorubicin-based chemotherapy. A 14-year-old spayed female Maltese (4.14 kg) was presented with progressive abdominal distension and anorexia. Imaging revealed a large retroperitoneal mass, and computed tomography identified a 12.1 × 8.0 × 8.5 cm heterogeneous tumour. Exploratory laparotomy confirmed the lesion was unresectable, and biopsy findings were most consistent with presumptive haemangiosarcoma (HSA) due to the small, cautery-affected specimen. Medical therapy was initiated with toceranib phosphate (10 mg every other day), followed one week later by propranolol (0.3 mg/kg twice daily) and piroxicam (0.3 mg/kg once daily). The patient was monitored every 2-4 weeks with physical examination and serial haematology and serum biochemistry. Two months after initiating therapy, the abdominal ultrasonography demonstrated tumour reduction to 4.9 × 2.7 cm, and after 7 months the mass was no longer detectable on radiographic follow-up imaging (radiography and ultrasonography). Throughout treatment, haematologic and biochemical values remained within reference intervals, no clinically significant adverse effects were observed, and the owner reported resolution of abdominal distension with improved activity. This case demonstrates that combined therapy with toceranib, propranolol, and piroxicam achieved radiographic and clinically sustained remission of unresectable canine presumptive HSA while preserving quality of life. These findings suggest that multimodal therapy targeting angiogenesis and tumour growth pathways may represent a promising alternative strategy for managing this malignancy and warrant further clinical evaluation.