The following information is simply informational. Its intent is not to replace the advice of a veterinarian nor to assist you in making a diagnosis of your pet. Please consult with your own veterinary physician for confirmation of any diagnosis. Your pet’s life may depend on it.


Hemangiosarcoma is a very aggressive, high-grade soft tissue sarcoma with the most common areas affected being the spleen and heart. A highly malignant cancer which preys on blood vessels, it can spread rapidly, causing tumors almost anywhere in the body. Hemangiosarcoma is insidious, as it attempts to build it’s own blood vessel network, making blood blister like formations which disrupts normal organ function. It is commonly in the advanced stage before detection, making it virtually a silent killer.

A common form of cancer, hemangiosarcoma affects mostly older, large breed dogs though all dogs, including young, can be affected. Males tend to have a higher rate of diagnosis than females, with German Shepards and Golden Retrievers more affected than other breeds.


There are three basics forms of Hemangiosarcoma:
dermal (skin), hypodermal (under the skin), and visceral (splenic or cardiac).

While the visceral form is most common, dermal and hypodermal have been recently studied in detail. Hemangiosarcoma is highly metastatic, and most forms of the disease are associated with a poor prognosis. The dermal form can potentially be cured with surgery alone, and many dogs may have a fair to excellent long-term prognosis. Dermal and Hypodermal Hemangiosarcoma account for 14% of all reported Hemangiosarcoma cases.


Dermal Hemangiosarcoma often appears as a dark to purple skin lesion, which may be raised and appear on non-haired areas like the abdomen. 30% of all dogs with dermal Hemangiosarcoma develop metastatic disease.


Hypodermal Hemangiosarcoma can occur anywhere on the body and may appear as a soft mass or be a firm invasive mass with ulceration. 60% of dogs with hypodermal Hemangiosarcoma develop metastatic disease.


Visceral Hemangiosarcoma accounts for 2% of all reported malignancies and up to 5% of all noncutaneous tumors in dogs. Although these numbers seem small, they have a significant impact on dogs, since this form of cancer kills. The spleen and the right atrium of the heart are the most common sites of occurrence of visceral Hemangiosarcoma. Dogs may have nonspecific signs such as lethargy, loss of appetite, weight loss or more specific signs such as difficulty breathing, pallor, or abdominal fluid. Regardless of the site of origin, visceral Hemangiosarcoma is locally invasive and highly metastatic. Up to 25% of dogs with splenic Hemangiosarcoma have cardiac Hemangiosarcoma and up to 63% of dogs with atrial Hemangiosarcoma have metastatic disease. Metastases commonly affect the lower mesentery, lungs, and brain.


Because these tumors arise in internal organs there is often little warning that they are present prior to time they cause severe clinical signs of disease. A common estimate of the average time from discovery of the tumor until death occurs in affected dogs is six to eight weeks but death occurs more rapidly than this in a number of cases.

Visible bleeding, usually in the form of nosebleeds, and signs associated with blood loss, such as tiring easily, episodes of unexplained weakness, pale color to the mucous membranes of the mouth and eyes, increased respiratory rates, abdominal swelling and depression are the most common presenting signs for patients with hemangiosarcoma. A few dogs just suddenly die with no clinical signs having been noted by their families prior to death. Bleeding disorders associated with hemangiosarcoma are sometimes confused with immune mediated hemolytic anemia (IMHA) because the type of anemia caused by the two conditions is very similar and early clinical signs are often very similar, as well. Hemangiosarcomas can cause very large tumors, sometimes as large as ten or more pounds, when they affect the spleen.

In most instances tumors of this size in this location are found on physical exam. In other cases the tumor affects the heart and is hard to find on a physical exam and even easy to miss or X-rays. Sometimes there are hundreds of small tumors spread throughout the body and surgical exploration or an autopsy are the only ways to identify the problem.

The blood disorder that most commonly accompanies the presence of hemangiosarcoma tumors is disseminated intravascular coagulation (DIC). This is blood clotting that is occurring inappropriately inside the blood vessels. It uses up all of the blood clotting elements rapidly and dogs with this condition usually have platelet deficiencies, increased blood clotting times, decrease in fibrin content in the blood and an increase in fibrin degradation products (FDPs). This is probably the cause of death in most dogs affected with hemangiosarcoma.

Diagnosis of hemangiosarcoma can be accomplished in a number of ways. Identification of a tumor in the spleen or heart raises a high degree of suspicion for this tumor. Abdominal swelling is also highly suggestive in an older large breed dog. If fluid is aspirated from the abdomen and it looks like blood it is even more suggestive of hemangiosarcoma. If blood is drawn and will not clot when left in the syringe it is another sign that a dog may have this tumor. In some cases careful evaluation of the type of bleeding disorder present is necessary to raise the suspicion of hemangiosarcoma.


Treatment and prognosis for Hemangiosarcoma vary by location. Cutaneous Hemangiosarcoma is often curable with surgery alone, provided the lesion is small and confined to the dermis. Cutaneous Hemangiosarcoma often occur in areas of glabrous skin on lightly pigmented dogs and arise as a result of sunlight exposure.Lesions that are larger or deeper may be either primary or metastatic lesions and warrant more aggressive treatment. Treatment of splenic, atrial, or subcutaneous Hemangiosarcoma consists of surgical excision of the primary tumor and adjuvant chemotherapy. Recommended chemotherapy for Hemangiosarcoma is single-agent doxorubicin, intravenously given every 3 weeks. Use of an indwelling catheter is important because of the catastrophic tissue slough that occurs after doxorubicin extravasation. Owners should be warned of the potential of cardiotoxicity. A total of 4-6 doses of doxorubicin are recommended. Median survival time after surgery alone is reported to be 2-3 months, with the addition of chemotherapy increasing the median survival time to 4-6 months. The VAC protocol may be useful; however it has a higher morbidity rate with no increase in survival time. Dogs with splenic Hemangiosarcoma that have ruptured may have a poorer prognosis than those not ruptured. Currently several drugs are being investigated for their antiangiogenic properties, and may be useful for treatment of Hemangiosarcoma in the future. Follow-up for Hemangiosarcoma should include monthly thoracic radiographs and physical examinations.


If you are aware of an ongoing clinical trial for hemangiosarcoma please send information to info@caninecancerawareness.org


TRIAL RESULT: J Vet Intern Med. 2000 Sep-Oct;14(5):479-85.

Treatment of canine hemangiosarcoma: 2000 and beyond

Clifford CA, Mackin AJ, Henry CJ.University of Pennsylvania, Veterinary Teaching Hospital, School of Veterinary Medicine, Philadelphia, PA, USA.Canine hemangiosarcoma (HSA) is an aggressive and malignant neoplasia with a grave prognosis. Surgery and chemotherapy have limited success in prolonging survival times and increasing quality of life in dogs with HSA. Advances in medical oncology are resulting in increased survival rates and a better quality of life for veterinary cancer patients. An understanding of mechanisms of metastasis has led to the development of new treatments designed to delay or inhibit tumor spread. Promising new treatment options include novel delivery systems (inhalation or intracavitary chemotherapy); use of immunomodulators such as liposome-encapsulated muramyl tripeptide-phosphatidylethanolamine; antimetastatic agents such as inhibitors of angiogenesis (interferons, thalidomide), matrix metalloproteinase inhibitors, and minocycline; dietary modifications; and gene therapy. Inhibitors of angiogenesis seem to be safe and, unlike conventional chemotherapy, do not induce drug resistance. Although many of the newer approaches are still under development and review, the use of multimodality therapy incorporating innovative treatment modalities may offer the best therapeutic option for dogs affected with HSA.

Publication Types:

  • Review
  • Review, Tutorial

PMID: 11012108 [PubMed – indexed for MEDLINE]

TRIAL RESULT: J Vet Intern Med. 2000 May-Jun;14(3):271-6

Evaluation of ifosfamide for treatment of various canine neoplasms.

Rassnick KM, Frimberger AE, Wood CA, Williams LE, Cotter SM, Moore AS.
Harrington Oncology Program, School of Veterinary Medicine, Tufts University, North Grafton, MA 01536, USA.

lfosfamide (3-[2-chloroethyl]-2[(2 chloroethyl)amino]tetrahydro-2H-1,3,2-oxazaphosphorine 2-oxide) is an alkylating agent with a broad spectrum of antitumor activity. The efficacy and toxicity of ifosfamide were evaluated in 72 dogs with spontaneously occurring tumors. Forty dogs (56%) had lymphoma, 31 (43%) had sarcomas, and 1 had a metastatic carcinoma. Five dogs received ifosfamide at dosages <350 mg/m2 IV. Neither toxicity nor response were observed, and the remaining dogs received ifosfamide at 350 mg/m2 (n = 18) and 375 mg/m2 body surface area IV (n = 49). Saline diuresis and the thiol compound mesna were used to prevent urothelial toxicity. Fifty-two dogs had measurable tumors and could be evaluated for response. Complete responses were seen in 1 dog with metastatic leiomyosarcoma of the urinary bladder and in 1 dog with metastatic cutaneous hemangiosarcoma. One dog with lymphoma had a partial response for 112 days. Six dogs with splenic hemangiosarcoma received ifosfamide postsplenectomy and their median survival time was 147 days. The acute dose limiting toxicity was neutropenia 7 days after administration of ifosfamide. The median and mean neutrophil counts 7 days after ifosfamide at 350 mg/m2 were 2,035 cells/microL and 4,773 cells/microL, respectively (n = 12). The median and mean neutrophil counts 7 days after ifosfamide at 375 mg/m2 were 2,500 cells/microL and 3,594 cells/microL, respectively (n = 37). No dog developed clinical or microscopic evidence of hemorrhagic cystitis. Ifosfamide appears safe to use in tumor-bearing dogs, and the evaluation of combination chemotherapy protocols that include ifosfamide should be considered.

PMID: 10830540 [PubMed – indexed for MEDLINE]


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Clifford CA, Mackin AJ, Henry CJ. — University of Pennsylvania, Veterinary Teaching Hospital, School of Veterinary Medicine, Philadelphia, PA, USA

PubMed, Published for MEDLINE, National Library of Medicine

Karen Leshkivich, DVM
Encyclopedia of Canine Veterinary Medical Information – Dr. Michael Richards,DVM
Commonly Treated Malignancies of the Dog – Michael D. Lucroy, DVM, MS, DACVIM(Oncology); Associate Professor of Oncology; Kerr Foundation Chair for Biomedical Laser and Biophotonics Research, Department of Veterinary Clinical Sciences; College of Veterinary Medicine; Oklahoma State University

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