Cancer. It’s a scary word and a scary disease. It is estimated that 1 in 3 dogs will develop cancer, making it the leading cause of mortality in dogs. This is a very real concern among pet owners. Transitional cell carcinoma (TCC) is a urinary cancer which accounts for ~2% of cancer in dogs (that's approximately 140,000 dogs in Canada alone!).
There has been new evidence showing that TCC and other metastatic cancers can be prevented through a healthy diet and lifestyle. Yes, you heard right. There is more research coming out to show prevention of cancer through changes in diet. In this study, dietary antioxidants found in fruits and vegetables can help reduce the damage caused by carcinogenic compounds that lead to the development of these cancers.
A 2005 study by researchers at Purdue University attempted to expand on the usage of fresh vegetables in canine diets as a preventative measure against cancer. The study called “Evaluation of the effect of dietary vegetable consumption on reducing risk of transitional cell carcinoma of the urinary bladder in Scottish Terriers” begins with the objective of evaluating if the frequency and amount of dietary vegetable and vitamin supplementation will decrease the risk of dogs developing TCC.
To reduce confounding results due to breed, only Scottish Terriers were used for this study. The researchers began by examining 56 dogs diagnosed with TCC and 10 dogs without any pre-existing urinary conditions.
Owners of the dogs completed a survey on the dietary habits of their animals, which included what ingredients were in their food and how much they were eating per day. These included a variety of diets ranging from kibble, to canned food, to gently cooked fresh homemade diets. Dogs were then grouped by how often they ate yellow-orange vegetables (carrots, sweet potatoes, etc.), green vegetables (beans, spinach, etc.), and cruciferous vegetables (broccoli, brussel sprouts, etc.). The total number of servings of vegetables consumed per week for each dog was then calculated and analyzed. Information on the frequency and dose of vitamin supplementation was also analyzed for each dog.
Results of the study found that only 50% of dogs in the study consumed vegetables on a weekly basis. Data showed that dogs which consumed vegetables, specifically yellow-orange and green vegetables, at least 3 times per week were associated with a 70% reduced risk of developing cancer. It was hypothesized that because these vegetables contain compounds like carotenoids, ascorbate, tocopherols, and selenium, they act in an anticarcinogenic manner and protect the dog from developing TCC.
When it came to vitamin supplementation, there were no differences in TCC risk reduction between the case and control groups. Research has shown that vitamin A and β-carotene act as antioxidants and produce a protective effect against tumor development. These compounds can be found in green and yellow vegetables so they don’t necessarily need to be given as an individual supplement.
The study also found that over 50% of the dogs were fed a dry kibble as their primary diet and if they were getting any fresh vegetables, it was in addition to their normal, daily meal. This may indicate a benefit to fresh-cooked dog food. Rather than relying on vegetable supplementation on top of the diet, fresh-cooked diets already include whole vegetables. Fresh-cooked diets also are not cooked or extruded at extremely high temperatures. This ensures the anticarcinogenic properties of vegetables are not destroyed during heating.
Overall, more research is needed in dogs to investigate the protective mechanistic effects of vegetables in preventing cancers. However, this statistical study suggests that the simple incorporation of fresh vegetables into your dog’s daily diet may be very beneficial in the battle against cancer.