Abstract: The present invention provides, amongst others, a means to overcome the problem of oxidative stress in the domestic cat and dog. There is provided a method for increasing the plasma vitamin E level in a cat or dog, the method comprising the step of administering to said cat or dog, an amount of Vitamin E sufficient to increase the plasma vitamin E level. There is also provided use of vitamin C in the manufacture of a dog or cat foodstuff for the prevention or treatment of a disorder which has a component of oxidative stress. The present invention utilizes an antioxidant cocktail to overcome the problem of oxidative stress in a cat or dog. Such cocktail can be used to prevent or treat a disorder which has a component of oxidate stress or to maintain, optimise or boost immunological response.