Internal Parasite Prevention Month: Roundworms

Roundworms (also known as Ascarids) are one of the most common internal parasites in both cats and dogs. This is why us at Central Veterinary Services thought it is important to talk about roundworms during Internal Parasite Prevention Month

Most of the time roundworm infections occur when the dog or cat is very young. Sometimes the kittens or puppies are even born with these parasites, or acquire these parasites before being weaned from mom. This is because some of the species of canine and feline roundworms can cross the placenta (trans-placental route), or can be shed in the mothers milk (trans-mammary route). Although trans-placental and trans-mammary are routes of transmission, the life cycle of the roundworm commonly starts with the L2 larvae being ingested either from contaminated soil, or from ingesting an intermediate host such as a mouse or rabbit with the L2 larvae within. The L2 larvae are released from the egg, and at this point they may go into dormancy, but often the larvae migrate through the tissues finding their way to the hosts lungs. Once in the hosts lungs they are coughed up, and then swallowed by the host. They grow to adulthood in the hosts small intestine, and produce eggs. The life cycle starts again when the host has a bowel movement with its first batch of roundworm eggs within. 

Roundworms in young puppies and kittens often produce vomiting, diarrhea, constipation and other non-specific symptoms. These worms are often tightly coiled and do not attach to the host like other parasites do (they are often described to us as "spaghetti-like"). They instead use an undulating motion (like swimming) to remain the small intestines, this is why vomiting is one of the common symptoms. Can you imagine something swimming in your stomach? It makes our stomach queasy just thinking about it. 

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So, for the reasons above, us at Central Veterinary Services believe in deworming all puppies and kittens during their initial visit to the clinic (a minimum of 2 doses). It is also recommended for dogs and cats to get yearly fecal examinations done (including a fecal smear and a fecal flotation) to ensure they have not been infected with this parasite from the environment. In hunting cats and dogs it may be recommended by your veterinarian to deworm your pet monthly using a prescription medication. Many heartworm prevention medications are also labelled for use against this parasite (and possibly others) therefore ensuring your pet is roundworm free!

Roundworms do pose a significant risk for humans. Contact with contaminated soil or feces can result in human ingestion and infection. It is also important that children not be allowed to play in areas where animals defecate to prevent transmission of this parasite. If you come in contact with contaminated soil and/or feces wash your hands immediately. Some of the symptoms associated with human roundworm infection are cough, shortness of breath, nausea, diarrhea, blood in stool, weight loss, fatigue, or presence of worm in vomit/stool. There is also the risk in humans for the larvae to migrate to the eye, this is termed ocular larval migrans, this could then lead to full or partial blindness. 

If you have any questions about roundworms, or any other internal parasites don't hesitate to call us at 204-275-2038. One of our Veterinarians, or Registered Animal Health Technologists would be happy to assist you. 


  • The Merck Veterinary Manual Eleventh Edition