Whether given as a supplement or as part of a diet rich in fruits and vegetables, antioxidants help the body in many ways.  Among their many benefits, antioxidants can induce cancer cell death, prevent cancer cell DNA reproduction, improve the body’s immune system response, and block enzymes used for cancer cell growth.  However, there is conflicting research about how antioxidants interact with chemotherapy and radiation. 

Some research indicates that antioxidants can help improve the effectiveness of conventional cancer treatments and decrease typical side effects.  Other research suggests the opposite -- that antioxidants actually decrease the effectiveness of chemo and radiation, although it’s not clear at what exact dosages they start to interfere with these conventional treatments.  Because of this conflicting research, to be safe, it is recommended that if you are giving your dog an antioxidant supplement, you should discontinue the supplements for 48 hours before and after a chemo or radiation treatment.  If you dog is getting weekly treatments, this may mean that most days of the week, your dog is not getting these extra antioxidants.

PRIMARY ANTIOXIDANTS – The most powerful and critical ones to include in your dogs’ cancer diet.

Vitamin C
Try to choose one from a natural source including bioflavanoid co-factors.  There are several different types of Vitamin C including Sodium Ascorbate, Calcium Ascorbate and Ascorbic Acid.  All will work, but they all have slightly different “personalities.”

Animal nutrition expert Kymythy R. Schultze, CCN, AHI in her book Natural Nutrition for Dogs and Cats, provides the following guidelines for each type of Vitamin C.

Calcium Ascorbate – Good for most pets but bitter, so you may have to gradually increase dosage.

Sodium Ascorbate – Most mild tasting, but can contribute to alkalinity when used in large doses.  This can lead to problems like urinary tract infections.

Ascorbic Acid – Very acidic, which may cause stomach upset in some animals, and also very sour which some dogs may not like.

The correct dose of Vitamin C for your dog is very hard to identify because the body has varying needs for this Vitamin and will self-regulate if it gets too much, meaning that you cannot overdose on it, but it is easy to underestimate how much the body really needs, especially under the stress of cancer.  As a result, it is recommended that you increase your dog’s Vitamin C dosage “to bowel tolerance.”   Gradually increase your dog’s dosage until you find that their stool starts to become softer, and then back off the dose to the last tolerated amount.  Of course, most dogs will experience periods of diarrhea or soft stools at some point during cancer treatments, so it may be hard to identify the true cause.  In this case, trust your instincts and gauge your Vitamin C dosage according to what feels comfortable to you.

Vitamin E
As with Vitamin C, Vitamin E also comes in several different forms, each having specific properties and benefits.  As a result, it is best to choose a supplement with “mixed tocopherals” for maximum benefit.  Wheat germ oil is a good natural source of Vitamin E, but is prone to becoming rancid, so be sure to only use high-quality, fresh wheat germ oil.

Vitamin A
Dogs can synthesize their own Vitamin A from beta-carotene found in vegetables.  In its pure form, however, Vitamin A can be toxic, so be cautious if you are using a Vitamin A supplement rather than supplementing with vegetables high in beta-carotene (such as carrots, pumpkin, sweet potato or collards).  This includes if you are using Cod Liver Oil as a Vitamin A supplement.  If in doubt, err on the side of caution.  Also, according to Dr. Martin Goldstein in his book, The Nature of Animal Healing, some research suggests that Vitamins A and E may compete for absorption in the intestines.  As a result, he recommends not giving Vitamin E and A supplements at the same time. 


SECONDARY ANTIOXIDANTS –  May also be beneficial depending on your dog’s specific health situation.

Coenzyme Q10
This supplement supports the heart and is specifically used with chemotherapy to reduce the cardiotoxic effects of the drug Doxorubicin (Adriamycin).  If you have a breed that is more prone to cardio side effects, such as a Great Dane, Rottweiler or Boxer, you will definitely want to add this supplement to your dog’s regimen.

Vitamin D
Known as the “sunshine vitamin,” dogs have the ability to synthesize some of their own Vitamin D from being exposed to sunlight, just as humans do.  The many benefits of Vitamin D are still being uncovered, and some research suggests that in addition to balancing calcium and phosphorus in the body and keeping bones healthy, Vitamin D may also help to prevent, and fight cancer.  Many Vitamin A supplements also include Vitamin D, including Cod Liver Oil, so depending on the supplements you are using, your dog may already be getting a Vitamin D supplement.

Selenium
Selenium is a mineral that acts as an anti-oxidant and according to the American Cancer Society, it may “help prevent the development and progression of cancer.”  Only a small amount is needed in the body however for results, and too much can be toxic.  Best dietary sources for Selenium for dogs include liver, kidney, poultry  and whole grains.

There are many other herbs and supplements that have antioxidant properties, many of which support specific organs of the body.  Antioxidants are a safe and effective way to help boost your dog’s ability to fight cancer.  However, as mentioned above, antioxidants can still have interactions and depending on the cancer treatments your dog receives, your vet may prefer to have you discontinue an antioxidant regimen prior to or after a specific treatment to help ensure that the cancer treatments are as effective as possible.  To design an antioxidant formula that’s right for your dog, and to prevent any possible interactions with chemotherapy or radiation treatments, it is best to consult with your veterinarian or a holistic vet.