Page 1402 - Clinical Small Animal Internal Medicine

1340 Section 11 Oncologic Disease

Metastasis larger, middle‐aged to geriatric dogs such as golden
VetBooks.ir static malignancy. The multistep process involved in retrievers, Labrador retrievers, and German shepherds.
With few exceptions, hemangiosarcoma is a highly meta­
Dermal hemangiosarcoma is most common in older
metastasis is shared by all solid tumors and includes the
thin‐coated, lightly pigmented breeds. Hypodermal HSA
creation of new blood vessels (angiogenesis), mobility dogs, median age 9 years. Dogs predisposed include
and invasion into surrounding tissue, embolism into appears in 9–10‐year‐old dogs, with no sex or breed pre­
circulation, evasion of host immune defenses, lodging dilection. Primary renal and retroperitoneal hemangio­
into capillary beds, and extravasation into a new envi­ sarcoma are extremely rare. The median age for both
ronment. A detailed description of this cascade is beyond forms is 10 years, with larger nonspecific breeds most
the scope of this chapter. commonly affected. With the renal form, there appears
Due to its intimate relationship with blood vessels, to be a predilection for males. Other primary sites
HSA is readily able to mobilize and metastasize. The most such as the tongue have no specific sex, breed or age
common route is via the vascular system but spread can predilection.
occur by tumor seeding onto the local organ parenchyma
and within body cavities after rupture.
Although the metastatic rate of hemangiosarcoma is Cat
regarded as high, the rate can vary depending on site of The mean age for cats with HSA is 10 years. There is
origin. The visceral and myocardial forms of HSA no sex or breed predilection in this species.
are characterized by an extremely high metastatic rate
(80–90%) to local (liver, omentum, other intraabdominal
organs) as well as distant locations (lungs, CNS). Other History and Clinical Signs
less common primary sites such as renal, retroperito­
neal, and lingual demonstrate metastatic rates of 75%, Dog
88%, and 45% respectively. Primary integumentary forms
have a metastatic rate of 30% for dermal, 35–50% for Visceral Nonmyocardial
subcutaneous, and 75–90% for intramuscular locations. Dogs with the visceral form of hemangiosarcoma can
present with a variety of symptoms, ranging from leth­
argy to acute death from hemorrhagic shock. The most
Epidemiology common presenting complaints are weakness, lethargy,
collapse, and gastrointestinal changes such as anorexia,
vomiting, and diarrhea.
Hemangiosarcoma accounts for 2–5% of cancers in the
dog, and between 0.5% and 2% in the cat. It is more com­ Patients often present with pale mucous membranes,
mon in the dog than in any other species, and has an delayed capillary refill time, tachycardia and/or arrhyth­
extremely high mortality. The dermal forms represents mias, poor pulse quality, and a palpable fluid wave in
<1% of all skin tumors in dogs and cats. Breeds such as the abdomen. If no rupture has occurred, findings
whippets, Italian greyhounds, greyhounds, English may be limited to a large cranial abdominal mass or
pointers, Dalmations, and Staffordshire terriers are at organomegaly.
higher risk due to their thin coat and light complexion.
Lightly pigmented cats do not carry the same risk for Myocardial
dermal HSA as dogs. However, they are prone to other Dogs with primary myocardial hemangiosarcoma
solar‐induced neoplasms such as squamous cell carci­ present with symptoms of pericardial effusion such as
noma. For dermal forms, there are no other known risk exercise intolerance, collapse, arrhythmias, and dyspnea.
factors in the dog and cat. The strong breed association They are at a higher risk for acute death due to the added
with the visceral and myocardial forms suggests an danger of tamponade. Physical exam findings may
inherited predisposition for dogs. There is no known include extreme weakness, tachycardia, muffled heart
predisposition for cats. sounds, and pulsus paradoxus.
Integument
Signalment Dogs with dermal HSA are often asymptomatic.
Symptoms of the hypodermal and intramuscular forms
vary greatly. Most patients present for lameness,
Dog
pain, bruising, swelling or a palpable mass that can
Hemangiosarcoma can arise in any breed at any age. range from firm to soft and fluctuant. All forms of integ­
The visceral and myocardial forms predominantly affect ument hemangiosarcoma can demonstrate ulceration.