Mr. Neilson had quite a shock waiting for him when he came home from work in the evening. In the back yard he found his previously healthy, 9 year old German Shepherd, "Gerta", dead with no apparent cause. When he brought her in to me for cremation he told me that he suspected his neighbor may have done something to her. Admittedly "Gerta" had been a bit of a nuisance barker and that had been a source of friction between the two households, resulting in calls to the Humane Society and citations in the past. Was it possible she was poisoned?
A brief post-mortem exam showed that Gerta had an abdomen filled with blood and a mass on her spleen about the size of a baseball. The neighbor was off the hook. Gerta had died as a result of a bleeding hemangiosarcoma, one of the more common reasons for unexpected sudden death, and much more common reason than nefarious actions by people in the neighborhood.
Hemangiosarcoma is a type of cancer that generally affects older, larger breed dogs. Hemangio means blood vessel, and sarcoma means malignant cancer. These tumors are essentially balls of abnormal, cancerous blood vessels that form primarily on the spleen, but can also appear in the liver, heart, and skin. Because the cancer cells forming these blood vessel clumps don’t stick together very well they tend to fall apart and allow profuse bleeding from the tumor. When hemagiosarcomas appear on the skin they bleed to the outside, which is hard to miss. The bleeding is difficult to stop without just surgically removing the mass, but hemangisarcomas confined to the skin tend to be less aggressive and can sometimes be cured by surgical removal. A tumor on the base of the heart pours blood into the pericardium, the sac around the heart muscle, which squeezes the heart to the point it cannot function. The most common place for hemangiosarcomas to form is on the spleen or liver where they leak blood into the abdomen. Sometimes the amount of bleeding is massive and fatal, and sometimes it is more minor, causing weakness and lethargy that gradually improves as the blood is reabsorbed back into the system over the course of a few days. Often an affected animal has been having subtle waxing and waning episodes of weakness for some time before the problem is discovered or a more serious bleeding episode becomes fatal.
The most difficult aspect of this condition is that the tumors are often too small to be easily detected by palpation or even x-ray, they do not cause pain, they do not cause obvious changes in blood chemistries, and until bleeding occurs they are generally completely silent. Ultrasound examination of the heart or abdomen is a good means of finding internal tumors, but it would require psychic powers or random scanning to catch them before problems appear.
When a tumor is discovered there are some treatment options. If the cancer is confined to the spleen, surgical removal of the spleen followed by chemotherapy may increase the survival time in some patients. Unfortunately the cancer has almost always spread at least microscopically to other parts of the body before it is detected, so surgery and chemotherapy are palliative, not curative treatments. Although I have had some patients live for a year after surgery and chemotherapy it is much more typical that dogs live no more than a few weeks after surgery, even when there was no evidence of disease beyond the spleen. Dogs with hemangiosarcoma spread throughout their liver or on their heart are generally not surgical candidates at all, and without surgery, chemotherapy does not do much in this situation.