How do I prevent my dog from getting roundworms?
Because roundworms can enter your dogs body in many different ways, it is essential to keep your dogs living area clean, remove feces 
regularly, and, if possible, prevent your dog from eating wild animals that may carry roundworms.
To get rid of roundworms that are passed from the mother dog, puppies should be treated at 2, 4, 6, and 8 weeks of age and then receive a preventive treatment monthly. Fecal (stool) examinations should be conducted 2 to 4 times during the first year of life and 1 or 2 times each year in adults. Nursing mothers should be kept on monthly preventive and treated along with their puppies to decrease the risk of transmission.
Many heartworm preventives also control roundworms. Ask your veterinarian about prevention and treatment choices that are appropriate for your dog.
How Do I Know If My Dog Has Worms?
If your dog is fully grown, it’s not always obvious when they have worms, so you might not know for sure. Symptoms for intestinal worms are more obvious in puppies: They might vomit or have diarrhea, and may also have a pot-bellied appearance and a dull coat. However, almost all puppies are born with roundworms, so even those that appear healthy will usually have some worms inside them.
Heartworms are more often diagnosed in adult dogs. These are worms that actually live inside your dogs heart, causing coughing and exercise intolerance.
How will roundworms affect my dog?
Adult roundworms live in the affected dogs intestines. Many dogs do not have signs of infection; however, dogs with major roundworm infections, especially puppies, show diarrhea, vomiting, weight loss, dull hair, and a potbellied appearance. The dog may cough if the roundworms move into the lungs.
You may notice the adult roundworms in your dogs feces or vomit. They will appear white or light brown in color and may be several inches long.