You Make The Diagnosis: Common Dog Parasite

Last week, a client brought in a fecal sample from their puppy. The dog had been given a medication to kill internal parasites called fenbendazole. What are the long white worms called? How did the pup get them? (The intestinal parasites or worms are the things that look like spaghetti noodles.)

Roundsworms dog

Diagnosis: Roundworms ( Toxocara canis)

Roundworms are a common problem in puppies. They can become infected from their mother’s while in the uterus (transplacental infection) or while nursing (transmammary infection) or by eating the infective larval form of this parasite. Once inside, the larva migrates through the pup’s body until it reaches the lungs. The pup coughs and then swallows the larva back into the gastrointestinal tract. Eventually, the larva matures into an adult worm in the small intestines and starts laying eggs to infect a new generation of dogs.

***Note: Roundworms can infect humans. Please check your pet’s feces for parasites at least once a year.

Source:                                                                                                                      -Rothrock, Kari and Shell, Linda. Ascariasis/Roundworms (Zoonotic) VIN, Associate Database, written 4/25/2006 and revised 9/19/2013.


Published by kristennelsondvm

Dr. Kristen Nelson grew up on a farm in Watertown, Minn., where she developed a deep love for animals of all kinds. She received a Doctor of Veterinary Medicine degree from the University of Minnesota, College of Veterinary Medicine. Kris then completed a small-animal internship at the prestigious Animal Medical Center in New York City. In addition to writing and speaking, she cares for small and exotic animals in Scottsdale, Az. Dr. Nelson is widely quoted in the media. Her credits include Ladies’ Home Journal, USA TODAY, the Los Angeles Times and numerous radio and television interviews. Dr. Nelson has written two books, Coated With Fur: A Vet’s Life and Coated With Fur: A Blind Cat’s Love. Kris and her husband Steve share their home with rescued cats, birds and a dog.