Hemangiosarcoma, classed as one of the soft-tissue sarcomas, hemangiosarcoma is a malignant tumor of the lining of the blood vessels. It can occur at any site in the body but 50% of these tumors are found in the spleen. (German shepherds and Northern breeds statistically are at higher risk for this cancer.) Hemangiosarcomas have been found in the heart, lung, liver, spleen, and skin. 

Typically, there are few symptoms until the cancer has progressed; a few dogs die of “unknown causes,” without exhibiting symptoms. So you see, the importance of necropsies and biopsies cannot be overstated.  This is a cancer where surgery and/or chemotherapy may offer more time, as opposed to malignant histiocytosis where there are no treatment options.

Common clinical signs are episodic weakness, often to the point of collapse, increased respiration, heart irregularities, and abdominal swelling. When the tumor is in the spleen it can grow very large and is usually felt during a physical examination. Hemangiosarcoma is often accompanied by a blood disorder that causes inappropriate clotting inside the blood vessels. X-rays and fluid aspiration can aid in diagnosis of this aggressive cancer. Treatment includes surgery and chemotherapy but the prognosis is very poor with this malignancy.

In cases of cardiac hemangiosarcoma, the tumor is located in the heart, resulting in fluid around the heart, which is often the only sign of the cancer. These cases are usually inoperable. Cutaneous hemangiosarcoma occurs when the tumor invades the skin. With early diagnosis and surgical removal, there is a good possibility for a complete cure. 

Cancers of this type occurring in humans have been linked to radiation and chemicals. Animal studies have demonstrated links to these cancers from biocides, some gasoline additives, and chemicals used in the manufacture of plastics.  The most important known carcinogens for malignant hemangiosarcoma are:

Arsenicals like those found in pesticides, especially Chromated Copper Arsenate (CCA) which is a chemical mixture consisting of ions of three elements (arsenic, chromium and copper). CCA is injected into wood by a high pressure  process saturates wood products with the chemical. CCA protects wood from dry rot, fungi, molds, termites, and other pests, and CCA-treated wood is most commonly used for decks, walkways, fences, gazebos, boat docks, and playground equipment. Other common uses of CCA-treated wood include highway noise barriers, sign posts, utility posts, and retaining walls. Effective, December 31, 2003, the EPA no longer allows the affected CCA products to be used to treat wood intended for most residential settings. Of course, those homes with CCA treated wood remain a source of contamination. Arsenic is readily absorbed through ingestion and inhalation.

Thorium dioxide used in high temperature ceramics, gas mantles, nuclear fuel, flame spraying, crucibles, medicines, nonsilica optical glass, in thoriated tungsten filaments, and as a catalyst.

Methyl nitrosamine
which is present in cigarettes, chewing tobacco, and snuff.

Vinyl chloride a colorless organic gas with a sweet odor, used in the manufacture of numerous products in building and construction, automotive industry, electrical wire insulation and cables, piping, industrial and household equipment, medical supplies.  Vinyl chloride is depended upon heavily by the rubber, paper, and glass industries.

Ionized radiation has also been linked to soft-tissue sarcomas. In the early 1900s, when scientists were just discovering the potential uses of radiation to treat disease, little was known about safe dosage levels and precise methods of delivery. At that time, radiation was used to treat a variety of medical problems. Later, researchers found that high doses of radiation caused soft tissue sarcomas in some patients. Because of this risk, radiation treatment for cancer is now planned to ensure that the maximum dosage of radiation is delivered to diseased tissue while surrounding healthy tissue is protected as much as possible.

© 2001 by
Barbara Bouyet: Excerpted from “Akita-Treasure of Japan-Volume II” by Barbara Bouyet, Magnum Publishing.

If you lost your Leo to any form of cancer, please participate in the Cause of Death Registry.  The information is being gathered by the Leonberger Club of America solely to give us all a better understanding of what diseases need more funding, more research and perhaps, more prevention.  Please work with us in memory of your wonderful Leonberger:  Cause of Death Registry

Please also visit the Canine Cancer Research Underway page.


Last updated 08/01/2017 .

© 2004  All Rights Reserved.


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Posted with permission and support from his breeder, Keri Campbell


Hause v. Lowen Imperial Moose (“Moose”)
Sire: Haue v. Lowen’s Gabriel
Dam: CH Zeldas Mazurka
Breeder: Kerilyn Campbell and Melanie Brown
Kennel:  Hause v. Lowen
DOB: May 24, 1997
Owner:  Tom and Karin Gutman
DOD: July 19, 2004
Cause of death: Hemangiosarcoma
Adult weight: 135 lbs 

Moose was the only puppy that survived birth out of eight.  During birth he was pulled out by his hind legs which caused permanent injury throughout his life, being weak in the back legs.  His mother was very sick, thus he did not suckle as a puppy.  We provided him with blankets and at times he took our cloths to suckle.  He and Linus were much alike in this regard.  He had an interesting personality.  When he did something “bad,” when scolded, he would turn his head away with indignation.  When we talked to him, he cocked his head at least 45 degrees.  He was very verbal and talked to us when there was a need.  His eating habits were voracious and consumed everything.  He particularly liked vegetables.  He was very close to his half-sister Bergie.  They often slept in the yard head on one another’s back.  Due to his leg injury, Moose went from point “A” to point “B” in a walk.  He only ran if the prospect was food.   He was a gentle soul with a big heart!  As a Therapy Dog, he brought forth extra smiles from those he visited, young and old.  In a nutshell, Moose exemplified the lyrics of a song in Lady and the Tramp, “What a Dog.”