Hemangioscarcoma: This cancer hits pointers, Labs and golden retrievers, as well as several other breeds. Hemangiosarcoma is a type of cancer that begins in the cells that line blood vessels. Tumors usually develop in the spleen, heart, or liver, although they can also been found in the skin, bone, kidney, brain, and other locations. Hemangiosarcoma is almost always malignant, and tends to develop slowly, but spread rapidly, so that clinical signs are often not noticeable until the tumors have metastasized and/or ruptured, causing acute shock and collapse. Researchers are seeking blood samples from affected dogs, as well as blood samples from healthy dogs older than eight years of age.