Diagnosis, Prognosis, and Treatment of Canine Hemangiosarcoma: A Review Based on a Consensus Organized by the Brazilian Association of Veterinary Oncology, ABROVET

Abstract

Hemangiosarcoma is a mesenchymal neoplasm originating in the endothelial cells of blood vessels; they can be classified as non-visceral and visceral types. Non-visceral hemangiosarcomas can affect the skin, subcutaneous tissues, and muscle tissues; visceral hemangiosarcomas can affect the spleen, liver, heart, lungs, kidneys, oral cavity, bones, bladder, uterus, tongue, and retroperitoneum. Among domestic species, dogs are most affected by cutaneous HSA. Cutaneous HSA represents approximately 14% of all HSA diagnosed in this species and less than 5% of dermal tumors, according to North American studies. However, Brazilian epidemiological data demonstrate a higher prevalence, which may represent 27 to 80% of all canine HSAs and 13.9% of all skin neoplasms diagnosed in this species. Cutaneous HSA most commonly affects middle-aged to elderly dogs (between 8 and 15 years old), with no gender predisposition for either the actinic or non-actinic forms. The higher prevalence of cutaneous HSA in some canine breeds is related to lower protection from solar radiation, as low skin pigmentation and hair coverage lead to greater sun exposure. Actinic changes, such as solar dermatosis, are frequent in these patients, confirming the influence of solar radiation on the development of this neoplasm. There are multiple clinical manifestations of hemangiosarcoma in canines. The diagnostic approach and staging classification of cutaneous HSAs are similar between the different subtypes. The definitive diagnosis is obtained through histopathological analysis of incisional or excisional biopsies. Cytology can be used as a presurgical screening test; however, it has little diagnostic utility in cases of HSA because there is a high risk of blood contamination and sample hemodilution. Surgery is generally the treatment of choice for dogs with localized non-visceral HSA without evidence of metastatic disease. Recently, electrochemotherapy (ECT) has emerged as an alternative therapy for the local ablative treatment of different neoplastic types; the use of radiotherapy for the treatment of dogs with cutaneous HSA is uncommon. There is greater consensus in the literature regarding the indications for adjuvant chemotherapy in subcutaneous and muscular HSA; doxorubicin is the most frequently used antineoplastic agent for subcutaneous and muscular subtypes and can be administered alone or in combination with other drugs. Other therapies include antiangiogenic therapy, photodynamic therapy, the association of chemotherapy with the metronomic dose, targeted therapies, and natural products. The benefits of these therapies are presented and discussed. In general, the prognosis of splenic and cardiac HSA is unfavorable. As a challenging neoplasm, studies of new protocols and treatment modalities are necessary to control this aggressive disease.

Pathological Characterization and Risk Factors of Splenic Nodular Lesions in Dogs (Canis lupus familiaris)

“…No predilection by sex has been described in the literature for the different splenic lesions in dogs [ 8 ]. However, some studies have shown a higher proportion of affected males than females [ 1 , 5 , 27 , 33 ], which coincides with the results of the present study, in which males showed an increased risk of developing splenic neoplasia. In this regard, it has been described that late-castrated females have a higher risk of developing tumors such as hemangiosarcoma and mast cell tumors than reproductively intact individuals [ 35 , 36 ], which suggests a possible protective role of estradiol [ 35 ].…”

“…This result is not under what is recommended by the current literature, where it is suggested to send the complete spleen to analyze at least five different histopathological sections and thus maximize the probability of detection of splenic neoplasia, especially in the context of a diagnosis of hemangiosarcoma [ 24 ]. Hemangiosarcoma is the most common malignancy located in the spleen and has a poor prognosis due to the high risk of developing metastasis [ 5 ]. It originates from pluripotent bone marrow cells in a pre-differentiation state that migrate to highly vascularized sites, where they undergo malignant transformation.…”

“…It originates from pluripotent bone marrow cells in a pre-differentiation state that migrate to highly vascularized sites, where they undergo malignant transformation. This could explain its high incidence in the spleen [ 5 ].…”

“…The most frequent clinical signs include weakness, lethargy, anorexia, abdominal distention, and weight loss [ 1 , 3 ]. Patients may present with hemoabdomen and anemia due to ruptured nodules [ 1 ], being more frequently associated with splenic malignancies, specifically hemangiosarcoma [ 4 , 5 ]. Splenic lesions can manifest as splenomegaly, which can be diffuse or mainly nodular [ 6 , 7 ].…”

Second degree AV block in a dog with cardiac hemangiosarcoma in the interventricular septum

“…The main haematological findings associated with cardiac hemangiosarcoma are leukocytosis with a left shift, anaemia (regenerative or non-regenerative) with the presence of schistocytes and acanthocytes, microangiopathic damage, vasculitis and acute haemorrhage. 19 In the case described, there was a severe non-regenerative anaemia present. Splenic hemangiosarcoma is associated with a paraneoplastic microangiopathic haemolytic anaemia that can occur secondary to erythrocyte damage due to abnormal tumour vascularity.…”