If you ask veterinarians and scientists about health of Companion Animals today, they will tell you that they see more and more cases of cancer. Statistics are equally alarming - according to Roman Margo, around 50% of Dogs are getting cancer nowadays (the exact number varies by breed, with 64% Golden Retrievers 64% getting cancer).1The prevalence of cancer in Cats is on the rise as well, with about 40% of cats suffering from this ‘silent killer’. These numbers are a huge increase from what we used to observe only 40 years ago, when cancer was a rare occurrence in Animals.

Cancer is killing our beloved Companion Animals earlier in their lives too. According to Armaiti May, a vegan veterinarian, Animals are becoming ill with cancer at a much younger age than ever was noticed in the past. Overall, there is worsening of health in dogs, especially in young Dogs. Richard Pitcairn, a well-known author of Complete Guide to Natural Health for Dogs and Cats, similarly reported ‘dramatic increase in degenerative diseases and chronic health conditions in Dogs. 2

Sadly, cancer now affects our Cats and Dogs more than it affects us, humans. Studies show that dogs have much higher rates of many kinds of cancer than do people, including 35 times more skin cancer, 4 times more breast tumors, 8 times more bone cancer, and twice the incidence of leukemia.3

What are the main causes of cancer in Dogs and Cats, and how can it be prevented?

Accumulation of toxins

When we look at this research, we see that cats and dogs are being overloaded with dangerous chemicals on a daily basis. An important study by the Environmental Working Group, entitled ‘Polluted Pets’, tested blood and urine samples from 20 dogs and 37 cats at the Virginian Veterinary Clinic.3 The investigation found that these animals were contaminated with 48 of 70 industrial chemicals tested (heavy metals, neurotoxins and carcinogens). Cats showed particularly high levels of methylmercury, a pollutant from coal power plants commonly found in sea food.3 On average, chemical levels were 5 times higher in these animals than what you would normally find in humans.3

Toxins come into our bodies from the food we eat, among other sources. The Polluted Pets study links high levels of toxicity in animals to meat farms, which are commonly situated in ‘very contaminated areas’. Environmental toxins, such as lead, end up in still living ‘meat sources’, which become ingredients in commercial pet food. In this manner, lead (one of the most dangerous toxins) ends up in bone meal - a commonly used as an ingredient in meat-based pet food products.3

Meat is a very toxic ingredient, by its nature. Toxic chemical compounds tend to accumulate up the food chain, predator animals bearing the most toxic load and plants the least. For this reasons, humans and animals that consume plant-based diet digest a lot less toxins than do meat-eating animals. According to Susan Pitcairn, vegans only have 2% of toxins compared to omnivores - quite a staggering difference. 2

 Feeding cancerous Animals to Animals

It is no surprise that commercial pet foods contain lowest quality ingredients that are not fit for human consumption.P. F. McGargle, a veterinarian and a former federal meat inspector, believes that cancer and other degenerative diseases of cats and dogs come from consumption of slaughterhouse wastes. According to him, mainstream pet food commonly contains ‘wastes, which include moldy, rancid or spoiled processed meats, as well as tissues too severely riddled with cancer to be eaten by people.’ 3 Feeding sick and dead animals, whose tissues are already toxic, to companion animals leads to higher chances of cancer in these animals.

One of the damaging effects of toxins in the animal body is through the weakening immune system. Toxins damage gut microbiome – the good microorganisms that support healthy immune system and protect us against germs and diseases.1

Cancer in pets has also been linked to obesity. Consumption of commercial pet food products by our cats and dogs resulted in obesity of epidemic proportions. An estimated 60% of Canadian pets are now either overweight or obese, according to the president of the Canadian Veterinary Medical Association Jim Berry.4 Indigestible junky ingredients and animal fats lead to obesity, which in turn contributes to conditions such as diabetes, osteoarthritis, and cancer.4

 Preventive effects of plant ingredients

Meat and fish are dirty, toxic products and avoiding them will reduce the toxic load in your companion animal’s body. Substituting animal products with health plant-based ingredients will prevent development of health issues caused by toxins.

Antioxidants – natural substances such as beta-carotene, vitamin E, lutein, etc. – have been shown to reduce the risk of some forms of cancer and other diseases.5Antioxidants exist in plenty in plant ingredients such as grains and vegetables and help protect cells from damage. They do so by reversing a naturally occurring process in the body that creates free radicals - highly reactive, unstable molecules that can damage the cells and contribute to growth of cancer and other chronic diseases. Phytochemicals are another kind of naturally occurring compounds that have been shown to neutralize free radicals and remove their power to create damage.5Like antioxidants, phytochemicals are readily available in plant foods such as fruits, vegetables, whole grains, beans, nuts and seeds.

Scientific research shows that consumption of vegetables by dogs slows downs and prevents cancer. In a landmark study by Purdue University and the American Veterinary Medical Association 6, guardians of 92 Scottish Terriers with developing transitional cell carcinoma (a.k.a. bladdercancer) and 83 healthy Scottish Terriers completed questionnaires about vegetable consumption of their dogs. This study found a strong link between dietary inclusion of vegetables and cancer-free diagnosis in these dogs. In fact, dogs who ate any green leafy vegetables had reduced the risk of developing bladder cancer by 90%, while dogs who consumed any yellow-orange vegetables like carrots reduced the risk by 70%.6 This study clearly demonstrates a direct link between plant ingredients and prevention of cancer in dogs.

Ingredients commonly found in plant-based foods for Dogs and Cats, such as soy, sunflower seeds, non-GMO corn, carrots, sweet potatoes, peas, beets, etc. are all rich in antioxidants, phytochemicals and other natural cancer-preventing compounds. Substituting animal ingredients with plant-based ones will help slow down or reverse the cancerous processes that we observe in our companion animals today.


Avoid raw meat and commercial meat-based products. Transition your companion animal to plant-based food, to slow down or reverse the carcinogenic processes caused by toxic ingredients.




1 Roman, M. (n.d.). Plant-Powered Dog Food Summit. In Plant-Powered Dog Food Summit. Retrieved from https://www.plantpowereddogfoodsummit.com/
2 Pitcairn, R. H., & Pitcairn, S. H. (2017).  Pitcairn’s complete guide to natural health for dogs & cats. Emmaus, PA: Rodale.
3 Polluted Pets: High Levels of Toxic Industrial Chemicals Contaminate Cats And Dogs. (2008). Environmental Working Group. Retrieved from https://www.ewg.org/research/polluted-pets#.WrFAnKjwa70
4 Obesity Poses Serious Health Hazards to Pets. (2015, September 1). Canadian Veterinary Medical Association. Retrieved from https://www.canadianveterinarians.net/documents/obesity-poses-serious-health-hazards-to-pets
5 Langseth, L. (1995). Oxidants, Antioxidants and Disease Prevention. International Life Sciences Institute Europe, ISLI Press, Belgium. Retrieved from https://ilsi.eu/wp-content/uploads/sites/3/2016/06/C1995Oxi_Anti.pdf
6 Raghavan, M., Knapp, D. W., Bonney , P. L., Dawson, M. H., & Glickman, L. T. (2005). Evaluation of the effect of dietary vegetable consumption on reducing risk of transitional cell carcinoma of the urinary bladder in Scottish Terriers. Journal of American Veterinary Medical Association227(1), 94–100. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/16013542

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11 February, 2021



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