This recipe for doggie cookies came from Rose's Christmas Cookies by Rose Levy Beranbaum. Kelp powder, available at health food stores and elsewhere, is very rich in vitamins, (especially B vitamins), and other minerals such as including potassium, magnesium, calcium, iron and iodine. EQUIPMENT: Cookie sheets lined with parchment or aluminum foil; rolling pin; 3-31/2" bone cutter or 2 1/2" round cookie cutter. Store in an airtight container at room temperature. The dough must be used immediately. The baked cookies will keep for many months.