Parasites: Roundworm Infections Roundworms live/target the intestines. Infection can occur through various paths.

An Overview of Canine Roundworm Infections

Canine roundworms belong to the ascarid worm family, members of which can infect dogs, foxes, both wild and domestic felines, and humans. These large worms live and feed in the small intestine of their host. Though all ages of dogs are susceptible to this parasite, puppies are generally hardest hit by infestations and may become seriously ill. Thankfully however modern medicine has provided us with a plethora of de-worming medications, so treatment and prevention of roundworms is relatively simple and highly effective.

How might my dog become infected?

Roundworm infections may occur in a number of different ways, however the most common way for a dog to become infected is through its mother. Worm larvae incubating in the female migrate through the body and invade developing fetuses. Puppies are then born with worms already living in their intestines. In addition, larvae may also be passed from an infected mother to her offspring via milk.

Adult dogs become infected when they ingest eggs that have been shed by another animal in its feces. Older dogs that ingest roundworm eggs rarely fall clinically ill, though they may harbor larvae for the rest of their lives. Dogs less than a few months old are much more likely to become infected after ingesting eggs. In these cases the eggs hatch into larvae when first ingested, then migrate through the liver to the trachea. Once they reach the trachea, the larvae are coughed up and swallowed again. This time the larvae stay put in the intestine and mature into adult worms, ready to start laying eggs of their own.

How is a roundworm infection diagnosed?

With small numbers of worms there is usually no clinical evidence of infection. As numbers increase however symptoms do appear and may become serious. Adult roundworms occasionally are passed in feces or vomit and because of their relatively large (4 or 5 inch) size are quite easy to see. The classic symptom of roundworm infection is a “pot-bellied” appearance, and other signs include lethargy, weakness, diarrhea, vomiting, abdominal pain, and a dull coat. Weight loss is often a sign of significant infection, and very large numbers of worms may sometimes cause an intestinal obstruction.

Once suspicion has been established because of physical symptoms of infection, definitive diagnosis is based upon fecal sample examination. Characteristic roundworm eggs are readily visible in the feces of infected dogs, and your veterinarian needs only to examine a small sample under the microscope to reach a diagnosis.

What are the treatment options for dogs infected with roundworms?

A number of very effective, very safe de-worming agents are available through your veterinarian. In fact, most puppies are de-wormed as a precaution as early as 2 or 3 weeks of age.

If your dog has been diagnosed as having an active infection of roundworms, 2 to 3 doses of the de-wormer will be necessary, as the drug kills only adult worms. Further doses are necessary to eliminate any newly matured worms that were larvae at the time of the first dose.

Roundworm de-wormer is now often combined with preventative heartworm medication. Your veterinarian will be able to provide you with more information regarding treatment and pharmaceutical methods of prevention.

Can canine roundworms infect humans?

Canine roundworms can infect humans, but in a different way than they infect dogs. Human children are often infected by ingesting eggs found in soil, dog feces, or other contaminated substances. Once in the body, the eggs can hatch and cause visceral larval migrans, a disease caused by the larvae migrating through liver, eyes, or nervous system of their human host. Such infections are rare, and normal levels of hygiene are usually sufficient protection against human roundworm infection.

What steps can I take to minimize the risk of infection for both my dog and myself?

Several steps may be taken to help decrease the likelihood that a roundworm infection will strike your pet or family member.

All puppies should be de-wormed at a young age, no later than three weeks of age, regardless of health status. In addition, females should be treated both before breeding and again during late pregnancy to reduce the risk of infection for her puppies.

Periodic preventative de-worming may be indicated for dogs at a particularly high risk of infection. This possibility should be discussed with your veterinarian.

Proper hygiene is perhaps the most important factor in preventing round worm infections in both humans and animals. The prompt disposal of dog feces is vitally important, especially in yards, gardens, and public parks. Dogs should be discouraged from toileting in areas frequented by children, such as sandboxes or playgrounds. Finally, strict hygiene such as hand washing before meals is important, especially in children.

Additional resources on the web: PetEducation.com Describes the most pertinent aspects of roundworm infection in an article designed for pet owners. International Veterinary Information Service Intestinal parasite reference guide for veterinarians.