A Link Between Stealth Pathogens and Malignancy?
Bartonella can hide in the cells that line blood vessel walls, and persistent infection may lead to malignant tumors, one study suggests.
STORY AT-A-GLANCE
Hemangiosarcoma (HSA) is a cancer of the blood vessels and in dogs is typically diagnosed when it is far advanced, resulting in a relatively low survival rate
Often there are no symptoms of HSA until a dog suddenly begins to hemorrhage and the cancer is diagnosed during treatment; when earlier signs do occur, they’re usually symptomatic of blood loss
Research indicates that bartonella bacteria is prevalent in tumor and nontumor tissue samples taken from dogs with hemangiosarcoma, which indicates it could be a factor in the disease
Standard treatments for hemangiosarcoma involve surgery and chemotherapy, but the prognosis is poor; integrative therapies can include specific Chinese herbal protocols, medicinal mushrooms and other nutraceuticals, and transitioning to a ketogenic diet
Dogs at high risk for HSA should undergo regular blood tests, including nucleosome screenings and abdominal palpation; an additional diagnostic to consider is regular ultrasound imaging of the spleen and heart
Of all the types of cancers that strike companion animals, hemangiosarcoma (HSA) is one of the sneakiest. More often than not, a dog suddenly develops internal hemorrhaging and HSA is diagnosed as a result of the crisis. By then, the disease has progressed to an advanced stage, resulting in a one-year survival rate of only 12 to 20%.
Hemangiosarcoma is almost exclusively a disease of dogs, though it does occasionally occur in cats. Pets of any breed, gender, and age can develop this type of cancer, but it's most commonly diagnosed in dogs between the ages of 6 and 13, and is slightly more prevalent in males. Predisposed breeds include German shepherds, labrador and golden retrievers, and Portuguese water dogs.1
Recent research into hemangiosarcoma in small breed dogs found similar survival statistics as large breed dogs; studies continue into the effect of spay/neuter on the incidence of hemangiosarcoma.
Hemangiosarcoma = Cancer of the Blood Vessels
Cancer can occur in any number of different organs in the body, for example, the intestines, liver, and bones. In hemangiosarcoma, the tumors develop in the endothelial cells that line the blood vessels of the circulatory system. Hemangio is the Greek word for blood vessel; sarcoma means a malignancy of connective tissues.
This tendency for growth in blood-rich areas is the reason these tumors are so often fatal. Hemangiosarcomas can suddenly rupture, triggering internal or external bleeding and massive blood loss, forcing owners and veterinarians to make difficult decisions within minutes of diagnosis.
Hemangiosarcomas can occur wherever there are blood vessels in the body, but most often develop in the heart and spleen due to their abundant blood supply. HSA is responsible for two-thirds of all heart and splenic tumors in dogs. This cancer is aggressive and highly metastatic, meaning it frequently spreads to other organs, including the brain, lungs, kidneys, skeletal muscle and bone.
Signs and Symptoms
Because dogs most often develop the visceral form of HSA that affects internal organs, frequently no signs of disease are present in the early stages. Even dogs with large tumors will show no symptoms early on. Once the tumors invade surrounding normal tissue and spread to other parts of the body, they can develop small ruptures that allow blood to escape into the abdomen, chest, the sac around the heart, or right below the skin (subcutaneous).
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 can include a decrease in appetite, mild anemia, and slight elevation of liver enzymes.
When the tumors metastasize, they aggressively invade the lungs, liver and/or intestines. As I touched on earlier, often dogs with HSA die abruptly when a tumor ruptures, causing severe hemorrhaging.
Signs of a life-threatening hemorrhage include weakness, a pale color to the tongue, panting, rapid heartbeat, weak pulse, a distended abdomen, and collapse. In dermal (in the skin) and hypodermal (just below the skin) hemangiosarcoma, a mass can often be felt in or under the skin. It may become ulcerated and bleed.
Bartonellosis May Play a Role in Hemangiosarcoma
Results of a 2020 study by researchers at North Carolina State University found that bartonella bacteria is extremely prevalent in the tumors and tissues of dogs with hemangiosarcoma.2 Interestingly, Bartonella was not prevalent in the dogs' blood samples, even though hemangiosarcoma is a cancer of the blood vessels.
According to an NC State news release, this work "further supports the connection between persistent infection and some types of cancer and adds to the evidence that Bartonella can remain and thrive, undetected, within tissue."3
Bartonellosis is an infectious zoonotic disease that can be transmitted from animals to humans and vice versa. In humans, the infection is also known as cat scratch disease or cat scratch fever, even though it's not always acquired through a cat's scratch or bite.
Bartonella bacteria can be transmitted to dogs via fleas, ticks, flies, biting flies, sandflies, mites and lice, however, it doesn't appear canines are a natural host for the pathogen. It is not yet known whether dogs, like cats, can transmit the infection to humans.4
Just as hemangiosarcoma is a sort of "stealth" cancer that lurks in blood vessels, hiding there until the damage is irreversible, the specific manner in which bartonella invades a dog's body seems to allow the bacteria to hide from both antibiotics and the immune system. This results in chronic infection, which in turn can create prolonged suppression of the immune system, making the dog more susceptible to other types of infections and diseases.
According to NC State study co-author Ed Breitschwerdt, a professor at the College of Veterinary Medicine, as quoted in the university news release:
"There are clear precedents for the involvement of bacterial infections in tumor development. Given the established links between chronic inflammation and cancer, we wanted to determine whether chronic infection of blood vessels due to bacteria could be a contributing cause of this cancer [hemangiosarcoma]."5
The NC State researchers evaluated samples from 110 dogs with hemangiosarcoma from across the U.S. They looked at tumor tissue, nontumor tissue and blood samples, and screened each for babesia, mycoplasma and bartonella — three types of bacteria specifically associated with blood infections.
Babesia wasn't detected in any of the dogs and mycoplasma was found in only 5. However, Bartonella was found in 80 of the dogs. Bartonella DNA was amplified and sequenced and was identified in 34% of tumor tissue and 63% of nontumor tissue, but not in any blood samples.
"Research in recent years has confirmed that persistent infection with or inflammation caused by stealth pathogens is a risk factor for developing cancer later in life," Breitschwerdt told ScienceDaily.
"With the exception of Helicobacter pylori, the emphasis on evaluating the relationship between infection and cancer has focused on viruses. But intracellular bacterial pathogens such as Bartonella may also play an important and previously uninvestigated role.
Bartonella is a stealth pathogen — it can 'hide' in the cells that line blood vessel walls, which is part of what makes it so difficult to detect. This work adds more evidence to the connection between infection and cancer risk, and demonstrates that molecular testing of whole blood samples does not rule out the tissue presence of this pathogen."6
Breitschwerdt says further studies are needed to determine if bartonellosis is in fact a cause of hemangiosarcoma in dogs. Toward that end, he and his colleagues are focused on creating more sensitive diagnostic testing.
Traditional Treatment Options for Dogs With HSA
There have been no significant advancements in the traditional treatment of canine splenic hemangiosarcoma in decades, 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 dogs with this disease — they don't provide a cure or give the animal extra years of life.
Because the disease isn't typically diagnosed until it's 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 one to three months; five to seven months is the average survival period for dogs who undergo both surgery and chemotherapy. Bottom line, 90% of dogs are lost within a year of diagnosis despite surgery and chemotherapy, and almost 100% die within two years. There has been no improvement in these survival times in nearly 30 years.7
Chemical-Free Treatment Options
Integrative veterinarians use a variety of nontoxic protocols to support patients with hemangiosarcoma, including IV vitamin C and curcumin, medicinal mushrooms, as well as Chinese herbs including Yunnan Baiyao.
Drs. Erin Bannink, Diplomate ACVIM (oncology) and Steve Marsden, DVM, ND, MSOM, Lac, created a specific Chinese herbal protocol for hemangiosarcoma that I and many other integrative vets have found beneficial for extending life. Bannink and Marsden are currently still accepting patients in a clinical trial using this customized regimen.
The University of Pennsylvania School of Veterinary Medicine has researched the use of medicinal mushrooms (focusing on Coriolus versicolor) in dogs with hemangiosarcoma, with promising results. For example, dogs with splenic hemangiosarcoma who receive no treatment live an average of 86 days, but some of the dogs given the medicinal mushroom complex as their only treatment lived over a year.
Many owners of dogs with hemangiosarcoma opt out of chemotherapy because it doesn't dramatically improve survival time, is expensive, and requires several trips back and forth to the veterinary clinic, which is stressful for both pet and owner. Many parents of sick dogs feel that overall, chemo treatments decrease their pet's quality of life.
An effective medicinal mushroom compound that is less expensive than chemo and also has no reported adverse side effects may help dog owners extend their pet's life without regular trips to the vet. Many integrative veterinarians include other nutraceuticals and herbal blends as well.
I also strongly recommend addressing nutrition immediately when a pet is diagnosed with cancer. Eliminating all dry food (kibble) is important because of the amount of starch included in these formulas. There is only one human-grade, fresh dog food for dogs fighting cancer on the market today. Feeding a high fat, low to moderate protein, ultralow carb diet is critical for providing the right macronutrients for pets battling cancer.
KetoPet Sanctuary has added additional medium chain triglycerides to homemade, raw meat based diets to also effectively address cancer with a change in macronutrients. Ketogenic diets help starve tumors and slow the rate of metastasis.
A ketogenic diet combats cancer because cancer cells use glucose as a source of energy. The primary source of glucose is carbohydrates. Malignant cancer cells have very limited ability to use fat as an energy source, and they use protein for energy only after it has been processed by the liver to form glucose.
Starch (which rapidly turns into sugar) is abundant in pet foods, including "grain-free" kibble. Hidden sources of starch in your pet's diet include potatoes, tapioca, lentils, chickpeas and pea products.
It's impossible to produce dry food without a starch component, so I recommend stopping all dry foods when your pet is fighting cancer (and if you want to prevent cancer, I also recommend eliminating dry food and the carcinogenic byproducts that occur during manufacturing).
KetoPet Sanctuary successfully utilized a ketogenic diet to slow, stop and even reverse different types of cancer in rescue dogs. Their protocol included a stringent 120-day plan that involved calorie restriction and a homemade, high-fat, carb-free, raw food diet. We investigated using the ketogenic diet for hemangiosarcoma and other aggressive cancers in a six-hour documentary called the Dog Cancer Series.
Another benefit of a maintenance ketogenic diet is it's calorie-dense, which can be very helpful for pets who have lost a lot of weight due to their illness. I also recommend checking vitamin D levels in dogs that have been diagnosed with any type of cancer and optimizing their levels through appropriate supplementation, if necessary.
If Your Dog Is a High-Risk Breed
I recommend yearly blood tests for at-risk breeds under age 10, and a complete blood count (CBC) every 6 months for older dogs at high risk. In my experience, mild anemia has been the most consistent clue there could be an underlying issue requiring further diagnostics. In addition, annual screening for circulating nucleosomes, which are blood markers of cancer, is now available through the Nu.Q test, which can detect up to 82% of hemangiosarcomas.
At these appointments, I also perform a careful palpation of the abdomen to check for any abnormalities or changes, but even then, it can be difficult to feel tumors hiding deep in a dog's abdomen.
In addition to regular bloodwork and abdominal palpation, a third option is ultrasound imaging. The spleen can be easily visualized during an ultrasound exam, as can any large, irregular masses within it. With early detection, it's possible to remove the spleen before the tumor ruptures or metastasizes.
If your dog is a high-risk breed, you might want to consider regular ultrasounds of the spleen and heart starting at age 5 to 7, repeated yearly. Ultrasound imaging is noninvasive, has no side effects, and is well-tolerated by most pets.
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 or there is metastasis to the lungs, 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, the prognosis is poor.
I don't recommend removing a cancerous spleen as the only form of treatment. The surgery may eliminate the symptoms of the current immune system meltdown, but it doesn't address why it occurred. If the only form of treatment recommended is a splenectomy without a lifestyle change, I wouldn't do it if it were my dog because statistically, you don't gain much.
However, if you aggressively address the immune crisis with an integrative veterinarian and are willing to supply a number of immune modulating supplements several times a day, a splenectomy in conjunction with a supplement protocol can extend your dog's quality of life in many cases.
Something else I never recommend is prophylactic splenectomy (removing a healthy spleen to prevent splenic hemangiosarcoma), since it is unlikely to provide a benefit in inhibiting the cancer. In addition, the spleen has an important role to play in the body.
Dogs can function without one, but it will have an impact on their health. The spleen is an important part of the lymphatic system, removing old blood cells and contaminants from the blood and circulatory system. It works with the immune system to defend the body from disease, and is the only resource for red blood cells other than bone marrow.
Final Thoughts
Because cancer of the lymphatic system is the number one type of cancer plaguing dogs and cats today, and because more and more dogs are being diagnosed with malignant spleen tumors (also associated with the lymphatic system and immune-regulation), I strongly encourage proactive owners to evaluate their pet's environmental chemical load before the detoxification and lymphatic pathways become overburdened.
Eliminate lawn chemical exposure (fertilizers, herbicides), indoor chemical use (including pest control, nonorganic cleaning supplies and floor cleaners, and air-scenting products), and pet beds sprayed with PBDE's (that means virtually all pet beds not labeled organic).
Also remove the chlorine and fluoride from your pet's water, feed a minimally processed, real food diet, and eliminate any mold issues (or other airborne toxins, including cigarette smoke) in your pet's living space.
Ask your veterinarian to titer in place of annual vaccines, re-evaluate the amount of monthly pesticides placed directly on your pet (all conventional flea and tick medications) as well as the chemicals you feed your pet (heartworm pills). Institute an intermittent detox program that includes manually rinsing chemicals off your pet, if needed.
Healthypets Disclaimer: This information is for educational purposes only and is not intended to replace the advice of your own veterinarian or doctor. Dr. Karen Becker cannot answer specific questions about your pet's medical issues or make medical recommendations for your pet without first establishing a veterinarian-client-patient relationship. Your pet's medical protocol should be given by your holistic veterinarian.