Differences between Chemo for Dogs and Chemo Therapy for humans. By Deborah Shores, DVM

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Although both dog and human cancer patients may have the option to receive chemotherapy as treatment, there are many differences in how and why chemotherapy is used and the effects it has. 

The perception for chemotherapy is generally not very accurate, as most people compare human chemo treatment to canine chemo. For many canine cancer patients, chemo is less stressful and less grueling than it is for humans. This is because the goals and outlooks for treatment in dogs and humans are quite different. 

With humans, the general intent is to cure the patient by eliminating the cancer. Because of this, human chemotherapy is much more aggressive and causes more severe side effects. A large variety of drugs are used at the same time. 

For dogs however, many times the cancer is already advanced by the time it is diagnosed and curing the cancer is not an option. So instead, the goal is often to extend the dog’s life as much as possible to ensure the highest quality of life for them. Because the goal is not to eliminate the cancer, the treatment is often milder and only a few drugs are used at the same time.(1) 

The major question that owners face after their dog has been diagnosed with cancer is what should we do? Some cancers respond well to treatment and can extend a dog’s life for over a year, while others aren’t affected much by treatment and may end up causing more stress than it is worth. Ultimately, this is a question that you must decide with your veterinarian and your family, considering the best thing you can do for your dog. 

Now, what are the side effects of chemotherapy in dogs? There are multiple chemo drugs that are used. Below, we’ll take a look at the most popular drugs used and the common side effects.(1,2) 

•  Vincristine

•This drug is primarily used to treat lymphoma and mast cell tumors. Side effects include diarrhea, loss of appetite, and tremors. Rarely, vincristine can leak outside the vein and can cause soft tissue to die and leave sores on your dog. It can also cause some neurological side effects, particularly difficulty coordinating the feet. Vincristine is not used to treat tumors in the nervous system as it is unable to pass into the brain. Vincristine is removed through the liver and the dosage may vary for dogs with liver issues. 

•  Cyclophosphamide (Cytoxan)

•This is an extremely powerful drug that is used to combat aggressive cancer cells, specifically bone marrow or blood cell cancers such as lymphoma. The side effects of Cyclophosphamide include hair loss, nausea, and urinary issues, such as bloody urine or chronic cystitis. A diuretic is often prescribed along with this drug. Although hair loss is rare with many types of canine chemo, it is a common side effect of this drug, especially in certain breeds like poodles. 

•  Doxorubicin (Rubex, Adriamycin)

•This drug is often used to treat lymphomaosteosarcoma, other forms of sarcomas, and melanoma. Doxorubicin is given slowly, over about ten minutes through an IV drip. Acute allergic reactions occur often and many dogs are also prescribed with an antihistamine. Doxorubicin results in cumulative cardio-toxicity, which means that your dog can only receive a certain amount of this drug before the heart is incapable of working correctly.  Your veterinarian or veterinary oncologist will monitor this closely to ensure that treatment is stopped before your dog receives too much. The bone marrow is also sensitive to this drug and often the white blood cells and platelets are affected. Nausea is also seen. 

While side effects from chemotherapy in dogs are typically mild, these side effects can take their toll on your dog’s quality of life during and after treatment. Many different supplements, herbs, nutritional support (such as a low-carbohydrate cancer diet) and even acupuncture can be used to help their bodies function to their fullest.(3)

B-vitamin supplementation can provide a boost of energy, ginger will help combat nausea, and herbs such as Bladderwrack help support proper immune system function. The herb Guduchi helps improve white blood cell response, which is important in dogs after chemotherapy.

In the end, deciding whether or not to start chemotherapy treatment is a choice that is up to you, your family, and your veterinarian. If you do choose to pursue a chemotherapy treatment for your dog, talk to a holistic veterinarian about what options are available to support your pet through the treatment process and beyond. 

Resources

(1)  DiBernardi, L. 2009. Goals for Lymphoma Rescue Protocols in Dogs. ACVIM Proceedings. Veterinary Information Network.

(2)  Frimberger, A. 2011. Chemotherapy in Private Practice Part 1. World Small Animal Veterinary Association World Congress Proceedings. Veterinary Information Network.

(3)  Silver, R. 2013. Integrative Oncology: Blending the Best of Conventional with Evidence-Based and Supportive Complementary Therapies. Holistic Veterinary Medicine Club Symposium Proceedings. Veterinary Information Network.

About Deborah Shores, DVM

Dr. Deborah Shores is a graduate of Mississippi State University College of Veterinary Medicine. She has many years of experience working both in private practice and industry from Virginia to South Carolina, treating mainly dogs and cats. She has a special interest in nutrition and holistic veterinary medicine and plans to pursue an acupuncture certificate at the Chi Institute in Florida. She has two cats and recently lost her 8 year-old Australian Shepard to liver cancer.X

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