Rosemary oil is a powerful antioxidant, preventing the breakdown of fats and oils in foods. To ensure a long shelf-life of their products, food manufacturers use rosemary oil in foods and in such things as soaps to preserve fats, and prevent them from becoming rancid over time.
While artificial preservatives, such as BHA and BHT, may extend the shelf-life of food longer than natural preservatives, their potential to be carcinogenic is much higher.
Because oxygen damage, or free radicals, in foods has been linked to cancer, there have been many studies done on the cancer-prevention quality of rosemary.
The findings are that animals whose diets contained some rosemary oil had about half the incidence of colon cancer or lung cancer compared with animals not eating rosemary.
So if you want to extend the shelf-life of your own homemade treats, and add a cancer-fighting ingredient at the same time, be sure to add some rosemary oil as a natural preservative.
Rosemary oil can be found at certain specialty food markets, and there are many online stores which sell it as well.
Rosemary can add its own strong flavor to your food when used as a preservative, so keep this in mind and don't use more then necessary for your treats.
When adding rosemary oil as a preservative to your dog treat recipes, add up to 10 drops to the liquid part of your ingredients before mixing your wet and dry ingredients together.