Cancer Options on the Horizon for Canines
By Cheri Eagleson, CTCA Foundation Trustee
What is cancer?
Cancer is a disease in which some of the body’s cells grow uncontrollably and spread to other parts of the body. Cancer can start almost anywhere in the body, which is made up of trillions of cells. Normally, cells grow and multiply to form new cells as the body needs them. When cells grow old or become damaged, they die and new cells take their place.
Sometimes this orderly process breaks down and abnormal or damaged cells grow and multiply when they shouldn’t. These cells may form tumors that can be either cancerous or not cancerous (benign). Cancerous tumors spread into nearby tissues and can travel to distant places in the body to form new tumors (a process called metastasis). Benign tumors do not spread into other tissues. When removed, benign tumors usually don’t grow back, whereas cancerous tumors sometimes do.
Unfortunately, dog cancer is common. It is the leading natural cause of death in dogs.
Approximately 50% of all dogs will be affected by a cancer in their lifetime; one report shows that 50% of dogs over the age of 10 will die from cancer. Cancer in cats is less common than in dogs. It’s probably half the rate seen in dogs, but feline cancer tends to be more aggressive. Lymphoma is the most common cancer in cats, followed by oral squamous cell carcinoma and fibrosarcoma in the muscle, also known as injection-site sarcoma.
What causes cancer in dogs?
This is the million-dollar question. While we don't have all the answers, we do know that there are contributing factors to cancer formation. Changes in the DNA within cells will cause cells to become cancerous. Known and suspected causes of cellular damage that may lead to cancer include herbicides, insecticides, second-hand smoke, environmental pollution, vaccinations, chemical additives, and preservatives in food.
Cheryl London DVM, PhD, DACVIM, through the VETGirl website, recently discussed advances in cancer diagnostics and treatment based on genetics. One exciting development is the use of a “liquid biopsy” for picking up cancers. This technique takes a blood sample collected in special tubes and then analyzes the DNA for mutations that have been associated with certain cancers. It not only shows if cancer is present but also can monitor if a pet has gone into remission or if there is a relapse. Clearly less invasive than a traditional biopsy, this option may give faster lab results.
Currently, liquid biopsies are FDA-approved for some human cancer. Some of those same DNA mutations have been identified in canine cancers. Some of these cancer mutations can provide risk factors for the development of resistance to treatment and likelihood of metastasis as well as evidence of a cancer being present.
Dr. London also mentioned “small molecule inhibitors” as treatments for various cancers. These compounds can be used alone or in combination with chemotherapy or radiation. The medications specifically target certain cell functions, usually tied into a mutation associated with the cancer they are being used for. A veterinary example here is toceranib phosphate (Palladia), which is approved for use in treating mast cell tumors in dogs. Laverdia CA1 (Verdinexor) is another drug of this type that recently received conditional approval from the FDA for treating lymphoma in dogs. These oral treatments can be administered at home.
Dr. Kate Megquier’s research through the Massachusetts Institute of Technology and the Board Institute found similar mutations in Golden Retrievers for lymphoma and hemangiosarcoma. Knowing about a specific mutation in a dog can help veterinarians devise specific, targeted treatments.
Tanovea (rabacfosadine injection) received full FDA-approval to treat lymphoma in dogs. It had been on conditional approval since December 2016. Lymphoma accounts for 24% of canine cancers and affects dogs as young as 3 years old. Some breeds, such as Golden Retrievers, Boxers, Bullmastiffs, Basset Hounds, Saint Bernard, Scottish Terriers, Airedale Terriers and Bulldogs, may have a genetic predisposition. Pulmonary fibrosis is a side effect, so this medication is not recommended for West Highland White Terriers, a breed prone to that condition.
How is cancer diagnosed in dogs?
Screening tests can be performed for dogs by VDI Labs to determine if your pet is at risk for cancer. Cancer is a form of inflammation; tests that show evidence of chronic inflammation can be used to assess risk. VDI labs also offers cancer risk assessment testing of dogs.
Semi-annual blood tests including a complete blood count (CBC) and full chemistry panel to assess organ function and electrolyte and mineral imbalances should be performed. A urinalysis should be included in testing. It is important to know what normal values are for your pet; if test results change, comparisons can be made.
More specific tests for cancer in dogs include the Nu.Q™ test which has a high success rate for early diagnosis of lymphoma and hemangiosarcoma. This test may also indicate other cancers such as histiocytic sarcoma and mast cell cancer. After leading in the research and development of Volition’s Nu.Q™ Vet Cancer Screening Test, the Texas A&M CVMBS is now offering this easy-to-use, cost-effective cancer test through their GI Lab. The Nu.Q™ test represents a significant development in veterinary medicine, as, until the release of this test, there were no accurate, simple and affordable ELISA cancer screening tests available.
VDI labs offers a canine cancer panel that can be used to diagnose the presence of cancer and to monitor disease progression or therapy outcomes. Common use includes diagnosis of lymphoma, abdominal masses, solid tumors, mast cell tumors (stage II), and hypercalcemia found on blood work that may be associated with malignancy, chemotherapy management and metastatic disease. The test is not recommended for skin masses, stage I mast cell tumors, or brain tumors. The panel includes TK1 (Thymidine Kinase 1) and C-Reactive Protein.
Some disease problems may interfere with cancer testing. Inflammatory diseases such as immune mediated disease, systemic inflammation, sepsis and trauma can also cause elevated nucleosome and inflammation levels. Tests may not differentiate between sick patients with systemic inflammatory mediated illness and cancer. For this reason, it is not recommended to run the tests in patients that could have these types of diseases. However, the test may be run in dogs without systemic inflammation but with other illness such as hypothyroidism, renal disease, osteoarthritis, mild or moderate pyoderma or other such minor illnesses.
Antech labs offers a test called the CADET-BRAF to detect the presence of transitional cell carcinoma in the urinary tract using urine samples.
Idexx labs announced new testing will soon be available to help diagnose and manage cancer, including:
- A liquid biopsy test that utilizes next-generation DNA sequencing technology to aid in diagnosing the most common canine cancers: lymphoma, hemangiosarcoma, and osteosarcoma.
- A diagnostic panel for biopsy tissues that is used to identify genetic mutations in canines, assisting in therapy selection and personalized treatment options.
- Newly designed diagnostic profiles to support cancer therapy management and monitoring.
Any lumps or masses should be evaluated as soon as possible if they are greater than one centimeter in size or have been present for more than one month. Masses felt on or under the skin can be aspirated; cells from the aspirate can be examined under the microscope to determine if they may be cancerous.
Impression smears using a microscope slide can be obtained from masses that are open or ulcerated.
Any mass that appears to be malignant should be biopsied, with full removal including clean margins, as soon as possible. Many times, surgical removal of a malignant mass will be fully curative.
Imaging to find internal masses may include radiographs, ultrasound, CT scan, or MRI.
How is cancer treated in pets?
There are many options for cancer treatment, including chemotherapy, immunotherapy, radiation and surgery, along with holistic or alternative therapies. Conventional treatment may be instituted if the pet is likely to live longer with treatment than without; however, financial constraints and difficulty accessing specialist oncology treatment centers may limit the options available.
Side effects from radiation and chemotherapy are variable. Both chemotherapy and radiation may predispose the pet to developing secondary cancers from treatment. For instance, cyclophosphamide is a proven bladder carcinogen and is associated with a 4.5-fold increased risk of development of kidney tumors.
The goal of any therapy is a high quality of life, not necessarily a longer life where the pet's health has deteriorated into a poor condition.
Holistic options may include:
Cancer cells have different metabolic needs than that of healthy tissues. Most cancer cells have an altered metabolism that allows them to break down sugar (glucose) to make energy. Tumor cells typically rely on significant amounts of sugar (glucose) to fuel their high-demand energy needs. Glucose is the primary source of energy for many types of cancers.
- Nutritional therapy with diet is designed to slow cancer growth and spread. These may include “keto diets” which are high-fat, moderate-protein, and low-carbohydrate diets. Limiting starches that break down to sugars is paramount in starving cancer cells. Do not feed dry kibble, potatoes, peas, or corn. Foods’s high in antioxidants and cancer-fighting chemicals that can be added to the diet include blueberries, blackberries, raspberries, parsley, basil, dark leafy greens, and oregano.
- Garlic can be fed to dogs (not cats). Dogs under 20 pounds can be fed 1 small clove per day. Larger dogs can eat a large clove. Fresh garlic is far superior to garlic capsules, dried garlic, or jarred garlic. Animal studies have shown that possible cancer-preventive mechanisms include inhibiting enzymes that activate carcinogens (potentially cancer-causing compounds), boosting enzymes that deactivate carcinogens, reducing inflammation that could support cancer development, supporting DNA repair, slowing growth, stimulating self-destruction of cancer cells without disturbing normal cells, and limiting cancer’s ability to spread by decreasing a tumor’s ability to grow new blood vessels.
- Digestive enzymes will help your pet absorb and utilize the nutrients in their food.
- If they are showing signs of muscle wasting, the Chinese herb Abundant Qi can help slow muscle loss.
- Acupuncture can be used to stimulate the immune system to attack cancer cells and decrease inflammation in the body.
- Mega-nutrients including vitamin, mineral, and nutritional supplementation may help. Arginine, green tea extract, broccoli, selenium, and turmeric are commonly used. Antioxidants such as vitamin C have been used effectively for cancer therapy.
- Fish oil has anti-inflammatory effects. The dose ranges from 1,000 to 12,000 mg per day of fish oil. Minimum EPA and DHA concentration together should be 300 mg per 1,000 mg fish oil.
- Medicinal mushrooms may be extremely beneficial. These include Reishi mushrooms, known as “the mushroom of immortality” because they help modulate the immune system, supports adrenal glands to manage stress, and helps regulate the digestive system. Lion’s Mane mushrooms are known for their neuroprotective effects. Chaga mushrooms have strong antioxidant function to protect DNA from oxidative damage, support the immune system, promote muscle strength, and help regulate blood sugar. Tremella mushrooms are supportive for animals undergoing chemotherapy, are an immune system tonic, and help protect the heart. Turkey Tail mushroom has the highest beta-glucan content of any medical mushroom, making it the most-used cancer-fighting mushroom. Turkey Tail boosts the production of the cells the body relies on to kill abnormal cells that can form tumors; it helps support a healthy immune system.
- Behavior modification can be used to reduce anxiety and stress for the pet and the pet parent. This may include incorporating essences, music therapy, essential oils, CBD, homeopathy, Emotion Code, and counseling.
- Toys that provide mental stimulation for both dogs and cats can help alleviate stress. Be sure to use treats that are meat or organ-based, not high-carbohydrate treats.
- Herbal therapies including Essiac Tea, Chinese herbs, Western herbs and Ayurveda. Yunnan BaiYao is used in most cases of hemangiosarcoma and other bleeding tumors.
- Neoplasene is an herbal formula that can be used topically or administered orally. The herb destroys cancer cells while preserving healthy cells. Neoplasene should only be used under the supervision of your veterinarian. When used topically on open tumors, the tumor will usually fall off in about ten to fourteen days.
- Artemisinin is an antimalarial herb that decreases the formation of new blood vessels; it also binds to the high iron content within cancer cells to help kill them. It should be given four hours before or after meals. A dose of 50 mg for small dogs and cats or 100 mg for medium to large dogs should be given twice daily for eleven days, then stopped for three days. Repeat in two-week cycles.
- Melatonin is a mild chelator and free-radical scavenger, decreasing oxidative damage to proteins and DNA. Melatonin directly eradicates various types of tumor cells by inducing apoptosis (programmed cell death) while inhibiting tumor and cancer cell growth. Melatonin is commonly used to induce sleep and should be given at night. Dosing is 0.1 mg per pound of body weight. Do not use liquids that contain xylitol.
- Homeopathic remedies that match the patterns present in the diseased state within the ailing patient.
- Energy work includes massage, Tui-Na, acupressure, Reiki, Craniosacral Therapy, Vibrational Healing, and TTouch.
- Ginger root (1/4 to 3/4 teaspoon per meal) may be given if the pet is vomiting or refusing food. Ginger tea can be given by dropper or syringe if the pet is not eating. Ginger has been found to activate immune system T-cells. It may lower blood sugar to starve cancer cells and may reduce the size of cancer tumors and causes apoptosis of both normal cancer cells and cancer stem cells.
- CoQ10 is a strong antioxidant and has cancer-fighting properties. Researchers at the University of Miami added CoQ10 to prostate cancer cells and found a 70 percent inhibition in growth over 48 hours. Adding CoQ10 to breast cancer cells also inhibited proliferation, without harming healthy cells. The team noted that treating a culture of melanoma cells with CoQ10 resulted in the death of all cancer cells within hours – and that applying CoQ10 topically to mice with melanoma tumors caused a 55 percent reduction in tumor mass. There was also a “profound disruption” of tumor vasculature, the structure of veins needed by tumors for oxygen and nutrition.
- S-adenosyl methionine (Sam-E) has been shown to prevent breast tumors from forming, reduce the growth of tumors already present, and decrease the number of metastases. It also has cell-killing effects on liver cancer cells. Doses range from 90 mg once daily for small cats and dogs up to 425 mg daily for large dogs.
- IP-6 or inositol hexaphosphate offers significant protection against cancer and metastasis. It increases the production of NK (natural killer) cells in the immune system that kill cancer cells. IP-6 binds to iron in the cancer cells which is a major source of food for the cells. It induces apoptosis (cell death) in many cancer lines and inhibits angiogenesis (new blood vessel growth for tumors). Doses for dogs range from 800 to 1600 mg twice daily for medium to large dogs and 400 mg twice daily for small dogs and cats.
- N-acetylcysteine (NAC) is a dietary supplement derived from the amino acid L-cysteine. It is used as an antidote for acetaminophen overdose. As an antioxidant, it is thought to reduce DNA damage. NAC is also marketed for its liver-protective properties and to support healthy immune functioning. In a 2017 study conducted by researchers from the Thomas Jefferson University, NAC succeeded in slowing down the growth of cancer cells in patients with breast cancer. The natural antioxidant reduced the aggressiveness of tumors by modulating the metabolism of cancer cells. NAC also depleted the cancer cells of nutrients, forcing them to starve and die. Dose is 1/4 tablet daily for cats and 1/4 tablet per 20 pounds body weight daily for dogs.
- MCT oil assists with burning fat instead of sugars for energy. Cancer cells thrive by utilizing sugar for energy. MCT oil can help the body make ketones, which the brain uses as an energy source.
- Research shows that milk thistle is an inhibitor to cancer cell cycles, effectively blocking cancer growth. In addition to its direct anticancer effects, milk thistle silymarin compounds may also reduce damage to the heart and liver from chemotherapy drugs. In lab studies, silibinin from milk thistle worked even better against breast cancer cells when combined with curcumin from turmeric.
- The incredible mix of immune and growth factors in colostrum can inhibit the spread of cancer cells. And, if viruses are involved in either the initiation or the spread of cancer, colostrum could prove to be one of the best ways to prevent the disease in the first place. Colostrum contains cytokines that can help enhance the body’s response to cancer and are thought to inhibit the growth of cancer cells. It supports the immune system and helps fight viruses which can initiate the growth and spread of cancerous cells. In addition, Colostrum contains lactoferrin, which is an anti-inflammatory substance that fights viruses and bacteria. It has been extensively researched for its role in treating and preventing cancer.
Open wounds and broken or ulcerated tumors on the skin are likely to become infected. Natural products are available that can help kill bacteria and keep the wound from drying. Dr. Judy Morgan’s favorite products are Buck Mountain Wound Balm, Remedy Salve, and French green clay. These topical products may eliminate the need to use antibiotics.
While not specifically labelled as chemotherapy agents, many drugs are used off-label to help fight cancer and decrease inflammation. These may include cimetidine, doxycycline, and fenbendazole, among others.
Are you feeling overwhelmed?
When your pet has been diagnosed with cancer, it is easy to feel helpless. It is important to educate yourself about your pet's cancer and how to care for your animal. Cancer treatment for animals focuses on alleviating pain and suffering, along with extending life, if their quality of life can be preserved. Treatment is typically much less aggressive than in humans.
Try to stick to your normal routine as much as possible, as our pets like routine. It helps them stay active and engaged, especially if they will have to make many visits to the veterinarian for treatment. Fun activities like exercise, walks, and playtime will help to maintain a healthy mindset for both you and your pet.
Just because an animal has been diagnosed with cancer does not mean its life is immediately over. Your commitment to your pet will help them enjoy life if possible.
- Cornell Canine Health Center, University College of Veterinary Medicine, NY Newsletter
- Dr. Judy Morgan: www.drjudymorgan.com
- Nu.Q™ Vet Cancer Screening Test: https://vetmed.tamu.edu/gilab/service/assays/nu-q-vet-cancer-screening-test/
- VDI Lab: www.vdilab.com
Editor’s Note: The opinions expressed in this article are solely those of the author and do not express the views or opinions of the Cairn Terrier Club of America.