Vitamin E in dog food or cat food is as important as Vitamin A supplement and Vitamin D3 supplement which are all fat soluble. Like most pet food on the market most of the vitamins such as Vitamin E tends to be synthetic vitamins which are added to the food to give it a proper balance. Many of the high-end petfood such as Royal Canin (Medium Adult) and also Kirkland Super Premium Lamb already have natural Vitamin E in their ingredients.
Effects: Vitamin E acts as an antioxidant and is required for normal reproduction in all animals. Note also that there are several forms of vitamin E on the market. The most biologically active form is know as alpha-tocopherol, which should be supplemented as alpha-tocopherol, alpha-tocopherol acetate, or alpha-tocopherol succinate. Vitamin E is also important for the formation of red blood cells and it helps the body to utilize Vitamin K.
Deficiency: A deficiency of vitamin E can lead to decreased reproductive performance, retinal degeneration, and impairment of the immune system. You need to speak to your vet about additional vitamins for your animals.
Sources: Wheat germ, corn, nuts, seeds, spinach and other green leafy vegetables, asparagus, vegetable oils.