When I was a kid, I hated mushrooms. HATED them! My mother, determined to get me to partake, would chop them up into bits and mix them in with ground beef stirred into spaghetti sauce. When she went to put the dinner plates away, she’d find a tiny pile of minced up mushrooms on the edge of my plate. Yes, I was stubborn. But Mom had the right idea ... mushrooms are potent little powerhouses of nutrition.
In terms of how humans use mushrooms, they can be broadly divided into three categories: those we eat, those that might kill you, and those with medicinal properties. It's this last category that we're most interested in today. Civilizations going back thousands of years recognized the power of mushrooms in certain disease processes, and veterinarians are also looking for ways these compounds can help our canine companions suffering from cancer.
Hemangiosarcoma is an aggressive cancer found almost exclusively in dogs, and one we see far too often in the clinic. One of the most insidious cancers due to its rapid growth, this sarcoma (connective tissue tumors) is found in the lining of blood vessels. While surgery and chemotherapy may delay the spread of the disease, it very rarely cures the cancer. Even with proactive treatment, fewer than 10% of dogs with this cancer are alive one year after the initial diagnosis. These therapies are invasive, expensive, and cause significant discomfort in and of themselves, so many pet parents do not pursue them.
A group of researchers at the University of Pennsylvania School of Veterinary Medicine investigated the effects of Coriolus versicolor, often referred to as turkey tail. It’s a mushroom commonly used in Chinese medicine, where it's regarded to have anti-tumor properties. Rather than using the whole mushroom, they used an extract of the bioactive agent and administered it to dogs with hemangiosarcoma ... and the effects surprised everyone.
In this study, 15 dogs with naturally occurring hemangiosarcoma were given standardized extracts of the turkey tail mushroom rather than the traditional US medical treatment (surgery plus chemotherapy). To the amazement and delight of the researchers, all 15 dogs showed significant improvement: it took longer for the cancer to spread, and overall survival time was increased. Dogs treated with surgery have a median survival of 19-86 days. However, in this study, dogs receiving the highest dose of mushroom extract had a median survival of 199 days! No, it wasn’t a cure, but more than doubling the time you have left without the need for surgery or chemotherapy, that is definitely worth celebrating!
While researchers have a general idea of how mushroom extracts work, the exact mechanisms have yet to be identified. The active agent in turkey tail, PSP, boosts the body’s own cancer-fighting abilities by improving the function of the immune system. Compare this to a traditional chemotherapy treatment, where a toxic agent kills both cancer cells and normal cells. As you might imagine, treatment with the mushroom extract is much better tolerated in patients than chemotherapy. In fact, in the Pennsylvania study, researchers found no evidence of adverse side effects!
In Japan, turkey tail has been used extensively as a treatment for many types of cancers, including gastric, breast, lung and colorectal cancer. And it’s not just this mushroom! Over 100 species of mushroom are used as adjunct cancer treatments in Japan and China.
There’s a reason you haven’t heard of it as much in the States. Here, mushroom extracts are classified as a supplement and not a drug, thus they are not regulated or approved by the FDA. It is, however, still available and the research is popping up all over the place. It’s on the radar of established treatment institutes such as Memorial Sloan Kettering. Keep in mind that all of this is a brand new avenue of research with much left to learn about why mushrooms might have a positive effect. Bottom line, don't rush out to buy something you don't understand, but rather have a conversation with your doctor before trying anything new.
While the veterinary studies are few and far between, mushroom extracts are promising enough that many veterinary oncologists are already starting to incorporate them into their treatment regimens. Although they are considered fairly safe, it’s always best to consult with your veterinarian before starting any new supplement. In addition to making sure it won’t interact with other treatments your dog is receiving, your veterinarian will be able to recommend a brand she trusts to provide a reliable, active dose of the extract. Not all supplements are produced with the same quality control standards.
The bottom line is that this is definitely an avenue that warrants further investigation. In fact, the study was so successful, the manufacturer of the PSP supplement plans to study its effects on human cancers, too!
Dr. Jessica Vogelsang, DVM