Most intestinal parasites can multiply at an alarming rate, so even a single intestinal worm can become a fast-growing problem. One female roundworm can lay up to 100,000 eggs in one day. One hookworm can produce up to 20,000 eggs in a day. In just one week, two puppies infected with roundworms can shed more than 20 million eggs and contaminate a 2800-sq. ft. backyard. Parasite eggs can survive in the soil for years. Although many deworming products claim to remove multiple parasites, some do not work as effectively or as thoroughly as others. Several dewormers, for example, leave certain worm species and their eggs behind. And some do not remove whipworms and/or tapeworms at all. That’s why it’s important to ask your veterinarian about dewormers that remove the broadest range of parasites and their eggs most effectively.