Overwhelmingly the most common intestinal parasite, puppies and kittens get roundworms from their mothers while still in the womb or from the first milk. Later they can contract roundworms from contaminated soil. Roundworms may cause mild vomiting and diarrhea in the young. Occasionally pets or adults pass spaghetti-like worms in their stool. Very rarely a severe worm load may cause a pot-bellied appearance, abdominal pain, dehydration, even death. Roundworm infestation is called toxacariasis.
Roundworm Life Cycle
- Roundworm eggs are swallowed by a puppy or kitten and hatch into larvae in the intestines.
- Larvae migrate out of the intestines and travel by the circulation to the lungs.
- The larvae break out of lung capillaries into the air sacs and tiny bronchioles.
- Coughing helps the larvae to travel up the air passages and windpipe to the back of the throat where they are swallowed once more and now mature into adult worms up to seven inches (17cm) long.
- Adult worms produce eggs that pass out in the feces and remain viable in the soil for up to a month.
- This migrating lifecycle stimulates an immune response. The next time larvae migrate out of the stomach the lifecycle is interrupted. Larvae become encapsulated ("encysted") in various body tissue.
- During pregnancy when the immune system changes, or during treatment with corticosteroids and at other times when a pet is either stressed or unwell, the immune system falters. Encysted larvae become active, break out of their cysts and complete their life cycle. Pregnant mothers pass roundworms to their puppies and kittens.
Diagnosis and treatment
Stool specimens are examined microscopically for worm eggs. We use a variety of parasite control drugs, according to the age and size of your pet.
Public Health Problems
Dog roundworms are a public health hazard, causing a condition called visceral larva migrans. A person, usually a child, accidentally consumes a roundworm egg from contaminated soil. The egg evolves into a larva but because it is in the wrong host it fails to complete its natural life cycle. Instead, it migrates to the lungs, liver, even the eyes where it encysts and provokes an inflammatory response. This causes anything from coughing or wheezing to blurred vision.
Routine use of effective wormers and cleaning up after your dog are the two most effective ways to reduce the incidence of toxacariasis. In London the fox has replaced the dog as the prime source of environmental contamination.