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 Published: 25 Jul 2025 | Last Updated: 25 Jul 2025 15:50:36

New research from the ¹ú²ú¸ßÇåavÍøÖ· VetCompass Programme has provided fresh insights into survival rates for dogs diagnosed with haemangiosarcoma, one of the most aggressive cancers in companion animals. Despite an association with extremely poor survival rates, this study reveals that outcomes can vary more widely than previously understood, particularly based on tumour location and treatment pathway.

Haemangiosarcoma, a fast-growing cancer of the blood vessels, is commonly diagnosed in older dogs. It has long been associated with extremely poor survival rates, often leading pet owners and first-opinion vets to opt for euthanasia at the point of diagnosis. The findings of this study challenge long-standing assumptions regarding this cancer and will support vets to have more nuanced and informed dialogues with owners about the most suitable next steps following diagnosis.

The cancer epidemiology research team formed by Dr Dave Brodbelt, Dr Dan O’Neill, Dr Collette Taylor, Dr Georgina Barry and Dr Sandra Guillen, analysed the records of 788 dogs diagnosed in 2019 under general practice care. Their analysis revealed that the median survival time (MST) for dogs diagnosed with hemangiosarcoma was just 9 days, with only 12% of dogs surviving beyond one year.

However, researchers found that survival times varied significantly depending on tumour location and that dogs who received surgical treatment or had skin (cutaneous) forms of the cancer lived considerably longer.

The study also found that dogs with a histopathologically confirmed diagnosis (tissue samples studied under a microscope) had an MST of 105 days, and 28% survived a year from the date of diagnosis, indicating that a proportion of dogs, especially those with early cancer stage, can benefit from surgery.

Importantly, the findings suggest that early euthanasia may be skewing perceptions of prognosis. This highlights the need for careful communication and support at diagnosis, as assumptions about prognosis could influence outcomes more than previously recognised.

Other key findings:

• While the MST across all cases was 9 days, the study found a survival range of up to nearly 5 years (1,789 days).
• Dogs with cutaneous haemangiosarcoma had an MST of 119 days, significantly longer than those with internal tumours like splenic hemangiosarcoma (4 days).
• The one-year survival rate for cutaneous haemangiosarcoma was 43.2% and 16% for splenic.
• Dogs with cardiac or hepatic haemangiosarcoma had the lowest MST at 0 days for both. The one-year survival rate for patients with tumours in these locations was 3% and 3.9%, respectively.
• Dogs with that received surgical treatment and had smaller tumours were both associated with better outcomes.

Dr Sandra Guillen, Lecturer in Veterinary Oncology at the ¹ú²ú¸ßÇåavÍøÖ·, and author of the paper, said:

“This study sheds light on the outcomes of canine haemangiosarcoma in the first opinion practice setting and challenges long-held assumptions regarding this cancer. By revealing that some dogs, particularly those with cutaneous forms or who undergo surgery, can live longer, it encourages us to move beyond a one-size-fits-all approach. It highlights the importance of open client dialogue, even in the face of a difficult diagnosis”.

Dr Collette Taylor, canine cancer epidemiologist at the ¹ú²ú¸ßÇåavÍøÖ·, and lead author of the paper said:  

“Our work here identifies a short survival time for dogs diagnosed with haemangiosarcoma in first opinion clinics in the UK. As most research for this cancer has focused on referral or specialist veterinary centre populations, these figures provide UK first opinion vets with the necessary data for contextualised care discussions when dog owners are faced with this much dreaded diagnosis. “Exploring early euthanasia and its impact on survival times is an important next step for haemangiosarcoma research.” The study was funded by the Morris Animal Foundation.

Notes to Editors

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Reference

Taylor, C., Barry, G.J., O’Neill D.G., Guillén, A. et al (2025) ‘Survival time and prognostic factors in dogs clinically diagnosed with haemangiosarcoma in UK first opinion practice’. PLOS ONE

The full paper can be accessed at:  

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About the ¹ú²ú¸ßÇåavÍøÖ·

• The ¹ú²ú¸ßÇåavÍøÖ· (¹ú²ú¸ßÇåavÍøÖ·) is the UK's largest and longest established independent veterinary school and is a Member Institution of the University of London. 
• It is one of the few veterinary schools in the world that hold accreditations from the RCVS in the UK (with associated recognition from the AVBC for Australasia, the VCI for Ireland and the SAVC for South Africa), the EAEVE in the EU, and AVMA (probationary) in the USA and Canada. 
• The ¹ú²ú¸ßÇåavÍøÖ· is ranked as the top veterinary school in the world in the QS World University Rankings by subject, 2025. 
• The ¹ú²ú¸ßÇåavÍøÖ· offers undergraduate and postgraduate programmes in veterinary medicine, veterinary nursing and biological sciences. 
• The ¹ú²ú¸ßÇåavÍøÖ· is a research-led institution, with 88% of its research rated as internationally excellent or world class in the Research Excellence Framework 2021. 
• The ¹ú²ú¸ßÇåavÍøÖ· provides animal owners and the veterinary profession with access to expert veterinary care and advice through its teaching hospitals and first opinion practices in London and Hertfordshire.