In addition, one in eight Golden Retrievers will be diagnosed with another malignant cancer called lymphosarcoma.
According to Amy Haase, DVM, writing for Suite101.com:
"Current theories about Golden Retrievers are increasing suspicion that this breed may lack a genetic ability to repair damaged DNA over a lifetime, thus explaining the increased tendency for lymphoma and hemangiosarcoma."
Splenic cancer is silent – evidence that a dog has the disease does not appear on routine blood tests taken to screen for other illnesses like liver or kidney disease. However, an ultrasound can help vets visualize problems with the spleen.
Per Dr. Haase:
The spleen is easily visualized by ultrasound, and normally appears as a very bright organ with a smooth, bright white and thick capsule that defines it well from other organs in the abdomen. Tumors will appear in various forms, but the most common and alarming appearance is a large irregular mass with multiple black cavities of blood divided by thin walls of tissue. These are the tumors that are at high risk for rupture and fatal bleeding.
Dr. Haase recommends that in breeds at high risk for splenic hemangiosarcoma, regular ultrasounds of the spleen should start at around age five and be repeated at least yearly. Ultrasounds are non-invasive, without side effects, and are well-tolerated by most pets
In addition to regular ultrasounds, it is also recommended that high risk dogs be seen by a vet every six months for a careful palpation of the abdomen to check for any abnormalities or changes.
Hemangiosarcoma is cancer of the endothelial cells - the cells that line blood vessels. Unlike other cancers, it is almost exclusively a disease of dogs.
Dogs of any breed and age can develop hemangiosarcoma, but it is most commonly seen in dogs over the age of six, and in the following breeds:
- Golden Retrievers
- German Shepherd Dogs
- Portuguese Water Dogs
- Bernese Mountain Dogs
- Flat Coated Retrievers
- Skye Terriers
Hemangiosarcoma generally develops slowly and no signs of disease are present in the early stages. Even dogs with large tumors will show no symptoms early on. Unfortunately, by the time a dog is symptomatic he is usually in an advanced stage of this life-threatening disease.
Fewer than half the dogs treated with surgery and chemotherapy survive more than six months after diagnosis. And many dogs die from uncontrolled internal bleeding before or during treatment.
Hemangiosarcoma Sites and Symptoms
The usual organs involved in hemangiosarcoma in dogs are the spleen, the right atrium of the heart and the tissue beneath the skin, called the subcutis.
The tumors invade surrounding normal tissue and also metastasize (spread to other parts of the body).
Over time, small ruptures in the tumors can develop which allow blood to escape into the abdomen, chest, the sac around the heart, or subcutaneously (right below the skin).
This blood loss causes some dogs to show intermittent symptoms of lethargy and weakness, but usually the signs are so subtle they go unnoticed or are attributed to another less serious cause.
Other subtle signs might include:
- Decrease in appetite
- Mild anemia
- Slight elevation of liver enzymes
When the tumors metastasize they aggressively invade the lungs, liver and/or intestines. Often dogs with hemangiosarcoma die abruptly from a ruptured tumor which causes severe hemorrhaging.
Signs of life-threatening hemorrhage might include:
- Pale color to the tongue
- Rapid heart rate and a weak pulse
- Distended, fluid-filled abdomen
Detection and Standard Treatments
There have been no significant advancements in the traditional treatment of canine splenic hemangiosarcoma in 20 or 30 years, probably because it's not a type of cancer humans get, so research funds are limited.
Unfortunately, available standard treatments can only moderately extend the life of a dog with this disease - they do not provide a cure or give the animal extra years of life.
As for early detection, there are currently no specific testing methods that detect the disease. An experienced pathologist might be able to pick up subtle abnormalities in bloodwork, but even at that, a definitive diagnosis can't be made from a blood sample.
I do recommend having annual bloodwork done on all high-risk breeds, and a CBC (complete blood count) done on high-risk breeds over 10 years of age every 6 months. At my practice, mild anemia has been the most consistent clue there could be an underlying issue requiring further diagnostics.
Because the disease isn't diagnosed until it is advanced, standard treatment is surgery to remove the spleen, followed by aggressive chemotherapy. Sometimes surgery isn't possible or practical, for example in cases of extensive spread to other organs.
Average survival time for dogs treated with surgery alone is about 90 days; 180 days is the average survival period for dogs that undergo both surgery and chemotherapy.
Routine Ultrasounds for High-Risk Breeds
The spleen can be seen easily with ultrasound imaging. High risk tumors will appear as large, irregular masses with numerous blood-filled cavities separated by thin walls of tissue. View video of a splenic tumor ultrasound diagnosis.
About half of all canine splenic tumors are malignant, and with early detection it's possible to remove the spleen before the cancer metastasizes to other abdominal organs or the heart.
Since there is a chance the heart may be affected as well, if a tumor is found on the spleen, the heart should also be visualized with ultrasound. If the heart is involved, surgery is probably not a good option due to the risks of anesthesia, as well as the fact that once the splenic tumor has metastasized to the heart, prognosis is poor.
If a splenic tumor is benign, surgery to remove the spleen can prevent an abdominal hemorrhage in the future.
Prophylactic splenectomy (removing a healthy spleen to prevent development of splenic hemangiosarcoma) is unlikely to provide a benefit because this particular type of cancer cell originates in the bone marrow. It is assumed if a target organ is removed that the transformed cells will simply find another organ to invade.
In addition, the spleen has an important role to play, and while dogs can function without one, it will have an impact on their health. The spleen removes old blood cells and contaminants from the blood and circulatory system. It works with the immune system to defend the body from disease. It is the only resource for red blood cells other than bone marrow.
Drawbacks to Yearly Ultrasounds
Ultrasound equipment is expensive, so not every veterinary office is able to offer the procedure. Because the equipment is expensive, the cost to pet owners can be significant.
The cost will also depend on who does the procedure.
If you take your pet to a specialist in internal medicine, it will probably cost more than if your vet is able to do it himself. There are also traveling ultrasound specialists who go from clinic to clinic as appointments are set for them. A general range for the procedure is from $300 to $600.
Another potential drawback is the skill of the person performing the ultrasound. It's to your benefit to insure the vet or other professional who performs the procedure is competent and experienced.
Another Cancer Detection Tool to Consider
A blood test is now available that detects the presence of a universal marker for malignant cell growth for 85 percent of common canine cancers, and with 95 percent specificity.
The test is highly accurate in detecting the presence of malignancy, but it cannot specify the type of cancer, what stage it is at, or if it has spread.
Vet offices are able to send blood samples away for processing, with results returned in about a week. Estimated cost to pet owners should be $90 to $120, plus shipping.
What You Can to Keep Your Dog as Healthy as Possible
The causes of cancer in dogs are not well understood, but there are a number of things you can do to give your beloved pup the best possible chance at avoiding disease, or fighting it off.
- Feed a nutritionally balanced species-appropriate diet which includes the right amounts of essential fatty acids.
- Insure regular and adequate exercise.
- Brush your pup's teeth every day.
- Keep your dog's immune system strong and resilient.
- Eliminate exposure to chemical toxins, including tobacco smoke.
- Reduce the number of unnecessary vaccines.
- Supply a whole food antioxidant.