Hemangiosarcoma can develop in many areas of the body, but most commonly the spleen, liver, and heart. Any tumor found in these areas would be highly suspect for this type of cancer. It can also develop directly on the skin, causing a lump in or around the skin.
The prognosis is usually poor for hemangiosarcoma, but chances of survival are better if found only on the skin. One thing I don't want to do, is scare or depress my readers with too much talk about cancer. However, I do think it's important to bring up, as the chances of cancer survival are much better if found at an early stage. With a dermal hemangiosarcoma it may be succesfully treated if caught early. This would involve surgery to remove the tumor, and possibly radiation or chemotherapy. Unfortunately, hemangiosarcoma with internal organ involvement has an extremely poor prognosis. With internal organ involvement, dogs who are treated with surgery and chemotherapy, only live up to one year on average.