Authorized Vendor for LifeSpan Dry Dog Food Chicken. PetGuard Premium LifeSpan is the first all natural premium food for dogs of all ages, sizes and breeds. These crunchy nuggets provide your dog with optimum nutrition in a scientific blend of real chicken, whole grains, essential vitamins and chelated minerals. No red meat; no by-products. PetGuard Premium LifeSpan is completely free of corn, soy, wheat and yeast..