The primary function of pet food preservatives is to stabilize fats
against oxidation. There are two types of antioxidants: natural and
synthetic.
Natural antioxidants most often used are Vitamins E (tocopherols)
and C (ascorbic acid).
Synthetic antioxidants
are butylated hydoxytoluene (BHT), butylated hydroxyanisole (BHA), and
ethoxyquin.
Commercially, ethoxyquin is the antioxidant of choice due to the
compound's stability in processing, efficiency, and apparent low
toxicity, and there is no evidence of detrimental effects when
consumed at very high levels over a long period of time. It is a
relatively expensive ingredient, so no more than necessary is
actually used in pet foods.
Comparatively, tocopherols (Vitamin E) have a limited degree of
effectiveness relative to the synthetic antioxidants such as
BHA & BHT. These synthetic antioxidants have been shown to be
three times more effective than tocopherols in preventing oxidation.
Ethoxyquin has been shown to be five times more effective than the
tocopherols; therefore, lower concentrations of synthetic
preservatives are used in pet foods relative to the amount needed
when using tocopherols or other natural antioxidants.
The FDA CVM has a legal maximum concentration of ethoxyquin at
150 ppm. However, most pet food manufacturers use less than 75 ppm
in both dog and cat foods.
Ethoxyquin has received much negative press from pet owners and
breeders. However, reports relating ethoxyquin to a wide spectrum of
illnesses in dogs have not been supported by scientific evidence. The
manufacturer of ethoxyquin has submitted the data from a large,
long-term, multi-generational study to the FDA on the effect of
feeding high levels of ethoxyquin to dogs. None of the dogs
demonstrated any clinical signs of illness.
