A Swedish pet health insurance claims that cancer is the leading cause of death. Out of 350,000 dogs, cancer claims 18 percent of these deaths. Is there anything the petfood industry can do to lower these numbers? What is the real effect of eating on cancer?
There is very little research data on evidence-based dietary guidelines to prevent or control canine cancer. Currently, one in four dogs have a high chance of developing cancer. As in humans, the prevalence of cancer in canines has increased in recent decades.
Factors such as nutrition, lifestyle, exercise and toxins are capable of altering the genetic component, either positively or negatively. For example, chronic inflammation induces epigenetic alteration, and has been shown to increase the risk of developing cancer in humans, the same can be said for dogs.
Research on the relationship between dog food and cancer
In the United States, the specialised animal health and nutrition company Alltech conducted research and tests on commercialised dog foods and, in addition to finding high levels of aflatoxins, 98 percent of the total of 965 foods tested were contaminated with one or more mycotoxins.
Grains such as corn, wheat, rice, as well as nuts and legumes, can become contaminated due to poor storage conditions. This contamination is caused by a mould known as aflatoxins. The first documented aflatoxin outbreak dates back to 1974, when hundreds of stray dogs in India died after eating corn kernels contaminated with aflatoxins.
In 1998, 55 dogs died from the same cause, and again in 2005, in the United States, more than 100 dogs died from petfood made from aflatoxin-contaminated food. As already discussed, aflatoxins are a powerful carcinogenic.
This study also found melamine and cyanuric acid in the food of three US brands, substances with which, in 2007, thousands of pets were poisoned.
Aflatoxins are capable of causing cancerous tumours through the consumption of contaminated food over a long period of time. It proves challenging to corroborate when the disease develops due to the consumption of this fungus.
In 2020, the Hong Kong Consumers Council made it public that three mass-marketed US petfood manufacturers had formulations containing aflatoxin B1 in their offering.
Two studies have determined the composition of the diet of dogs with breast cancer. One was conducted in Philadelphia, USA, and the other in Madrid, Spain.
Both studies included a quantitative questionnaire about the influence of food frequency on the dietary intake of proteins, fats, and carbohydrates. In the study conducted in the US, it was found that dogs with mammary tumours consumed slightly less fat and more carbohydrates. However, the opposite was observed in the Spanish study.
These two studies indicated that the composition of the diet, expressed as energy percentages of the macronutrients, is not exclusively related to the risk of breast cancer in dogs. Instead, they both identified an equal risk factor: being overweight in youth.
In the study conducted in the USA, it was shown that dogs that were lean at one year of age had a lower percentage of breast cancer in adulthood. In the same way, the Spanish study showed dogs with obesity at one year of age developed breast cancer in a higher percentage.
These results allow us to affirm that preventing young, overweight dogs not only contributes to longevity, but also delays the development of mammary tumours in female dogs.
Another study examined the relationship between vegetable consumption and bladder cancer in the Scottish Terrier breed. Results showed that carrot consumption could have potential benefits in preventing the development of cancer in dogs.
Other relevant data
Heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs) are chemicals that are formed when muscle meat is cooked at high temperatures. They are mutagenic, meaning they can alter the structure of DNA. In fact, research has emerged suggesting that these chemicals increase the risk of cancer in humans and some animals such as rats. This shows that when extruding food, we need to be very careful with the temperatures used throughout the process.
Since 1930, it has been known that glucose is related to the growth of cancer cells. Back then, it was discovered that cancer cells exhibit a higher rate of glycolysis than normal cells, meaning they generate energy to grow from the breakdown of glucose. This means we need to reconsider the amount of carbohydrates that food contains.
Conclusion
More research is still required to determine the extent of the link between dog food and cancer development. However, it is still important to remember, both for the industry and owners, that each bite an animal ingests will have positive or negative effects on its body and health.
It is very likely that the composition of a diet affects both the development of canine cancer and the course of the disease, but in truth there is only fragmentary information from published research to support this.
