VEGFA and hemangioma: Angiogenesis is a fundamental component of primary tumor cell proliferation and metastasis, particularly in HSA.[21,48–52] Specifically, dogs with HSA have increased amounts of plasma VEGF compared to healthy dogs,[48] VEGF and its receptors are present in tumors (when evaluated with IHC)[52] and upregulated in HSA compared to benign hemangioma[49] (and in xenograft tumors using a mouse model)[50].