a chew toy for animals is molded into the shape of a familiar animal food item , such as a dog bone , from a polymer composition which is both edible and degradable . the composition is essentially comprised of a starch material and a degradable ethylene copolymer , preferably poly - ethylene - acrylic acid or poly - ethylene , vinylalcohol . the preferred weight ratio of the ethylene copolymer and the starch material is within the range of about 1 : 1 to 2 : 1 . plasticizers and edible lubricants can also be added to the composition .