ISSN 2398-2977      

Hemangiosarcoma: overview


Synonym(s): Angiosarcoma


  • Cause: rare tumor of vascular endothelium.
  • Signs: primary site often impossible to define due to rapid metastasis. 
  • May occur as focal cutaneous masses, masses with local infiltration, internal masses restricted to one organ or disseminated neoplasia affecting multiple organs.
  • Most commonly located in skin, conjunctiva or in muscles as primary lesion:
    • Intramuscular hemangioma/hemangiosarcoma are commonest internal form - rapid metastatic spread to lungs and other organs including gut.   
    • Cutaneous vascular lesions are often less aggressive (hemangiomas) but these may still be malignant and locally invasive.
  • Cavernous hemangioma is a rare skin tumor that is found in neonatal foals Skin: cavernous hemangioma 01 - ventrumSkin: cavernous hemangioma 02 - pastern:
    • Arabian foals over-represented but also Thoroughbred Thoroughbred and crosses. 
    • Possibly vascular endothelial anomaly rather than tumor, but some are highly invasive.
  • Occasionally affects the spleen - may be present with abdominal discomfort following competitive exercise.
  • May affect horses of any age, but usually reported in middle-aged to older horses. An age range of 3-27 years has been reported, but it is very uncommonly found in young horses. No breed or sex predisposition has been reported.
  • There may be a subpopulation of young horses <3 years old with hemangiosarcomas in which dissemination is less common. Many of these are congenital and are frequently external tumors. These appear to be slowly progressive and primarily affect the musculoskeletal system.
  • Short course with rapid deterioration usually in malignant forms.
  • Diagnosis: ultrasonography, scintigraphy, biopsy, radiography.
  • Treatment: surgery.
  • Prognosis: poor.
See Intestinal neoplasia: tumor types table.



  • Tumor (malignant or benign) of vascular endothelial cells.


  • Rapid progression.
  • Early lesions not detectable so by the time it is obvious it is usually untreatable and outlook is bleak.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Taintor J (2014) Haemangiosarcoma in the horse. Equine Vet Educ 26 (9), 499-503 WileyBlackwell
  • Hollis A R (2011) Paraneoplastic syndromes. Equine Vet Educ 23 (4), 184-185 VetMedResource.
  • Dawson D R et al (2009) Epithelial variant of haemangiosarcoma in a gelding. Equine Vet Educ 21 (10), 519-524 WileyBlackwell.
  • Burks B, Leonard J M, Orsini J A & Trombetta M (2009) Interstitial brachytherapy in the management of haemangiosarcoma of the rostrum of the horse: Case report and review of the literature. Equine Vet Educ 21 (9), 487-49 3 VetMedResource.
  • Cottle H J, Hughes K J, Philbey A W & Pollock P J (2008) Primary haemangiosarcoma in the proximal humerus of a Clydesdale gelding. Equine Vet Educ 20 (11), 575-579 VetMedResource.
  • Bischofberger A S, Konar M, Posthaus H, Pekarkova M, Grzybowski M & Brehm W (2008) Ocular angiosarcoma in a pony - MRI and histopathological appearance. Equine Vet Educ 20 (7), 340-347 VetMedResource
  • Sansom J et al (2006) Hemangiosarcoma involving the third eyelid in the horse: a case series. Equine Vet J 38 (3), 2772-82 PubMed.
  • Johns I, Stephen J O et al (2005) Hemangiosarcoma in 11 young horses. J Vet Intern Med 19 (4), 564-570 PubMed.
  • Knottenbelt D C & Clegg P D (2004) Unilateral hindlimb swelling may be a sign of serious disseminated neoplasia in horses. Equine Vet Educ 16 (1), 7-11 VetMedResource.
  • Head M J (2004) Presentation, diagnosis and post mortem evaluation of musculoskeletal neoplasia in a 14-year old Warmblood gelding. Equine Vet Educ 16 (1), 2-11 VetMedResource.
  • Kuipel M, Frank N, Stevenson G W, Siems J & Snyder P W (2000) Intrapelvic haemangiosarcoma in a horse. J Vet Diag Invest 12, 91-95 PubMed.
  • Valentine B A, Ross C E, Bump J L & Eng V M (1986) Intramuscular haemangiosarcoma with pulmonary metastasis in a horse. JAVMA 188, 628-629 PubMed.
  • Frye F L, Knight H D & Brown S I (1983) Hemangiosarcoma in a horse. JAVMA 182, 287-289 PubMed.
  • Waugh S L, Long G G, Uriah L & Grant B D (1977) Metastatic haemangiosarcoma in the equine: report of 2 cases. J Equine Med Surg 1, 311-315 AGRIS.
  • Baker J R & Leyland A (1975) Histological survey of tumours of the horse with particular reference to those of the skin. Vet Rec 96, 419-422 PubMed.

Other sources of information

  • Hollis A R (2015) Paraneoplastic Syndromes. In: Current Therapy in Equine Medicine. 7th edn.
  • Knottenbelt D C, Patterson-Kane J C & Snalune K L (2015) Clinical Equine Oncology. Elsevier, UK.

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