Worm-like creatures in dog feces may be intestinal parasites, such as tapeworms, but fly larvae, also known as maggots, can rapidly colonize fresh fecal piles, often confusing owners, writes veterinarian Jeff Kahler. Dogs acquire tapeworms from fleas that carry tapeworm eggs, so treatment for tapeworms includes medicine to kill the worms and flea treatment to rid the dog of fleas. Fly larvae in feces are easily prevented — just promptly clean up after dogs, notes Dr. Kahler.
By JEFF KAHLER, D.V.M.
Darren was picking up his dog Robo’s waste and noticed white, wormlike creatures crawling in and on several of the stool piles. He finished cleaning up and then called the veterinarian.
Darren said Robo was prescribed medication to treat tapeworms. The dosage required several pills to be taken all at once by Robo. Darren followed the protocol and assumed the creepy little creatures were history. That was wishful thinking; about a week later, they were back on Robo’s stools.
Darren again treated Robo for tapeworms. This time, he also treated Robo for fleas, as tapeworms are often associated with fleas. Darren also began to scrutinize every stool Robo produced. His skepticism was rewarded as the ugly little beasts reappeared within the next week after the second treatment. Well, Darren wants to know what the heck is going on!
Darren needs to harvest stool samples containing the worms and have them examined by Robo’s veterinarian. I believe these wormlike creatures are not worms, but the insect larvae of flies.
If Robo had tapeworms, I would expect the initial treatment to have worked. There would not have been enough time for a new population of tapeworms to develop inside Robo in the week after the first treatment.
Tapeworms are intestinal parasitic worms that occur in several species of animals. The more common type in dogs is carried on the flea. When a dog bites at a flea, it can take in the tapeworm eggs by mouth and swallow them. This starts the development process in the dog’s intestinal tract, which culminates in a population of adult tapeworms. These adults mate and produce small segments that break off the adult worm and are passed in the stool. These appear as tiny, whitish, wormlike creatures that can wiggle and crawl in an undulating fashion. This fits with Darren’s description and his veterinarian’s assumption that Robo had tapeworms. These segments will dry up and appear similar to rice grains over time. The segments will eventually rupture, and the eggs inside stick to fleas and start the whole cycle over again. This is why it is important to treat for fleas when treating for tapeworms.
Of course, we know that Robo does not have tapeworms. In fact, Robo’s stool is not indicating he has any visible parasites.
Robo’s stool is likely colonized by fly larvae, most commonly referred to as maggots. Flies will lay their eggs in fresh dog feces and these will hatch into larvae that then feed on the fecal material. When the weather is warmer, hatching time can be very quick. I know, you’re thinking, “Yuck,” and frankly I am, too. I am not a big fan of maggots, but they are a part of the circle of life and nothing to be concerned about in the disease realm. If Darren were to pick up Robo’s stools more frequently, the fly eggs would not have time to hatch before disposal and would therefore not be seen.
(Jeff Kahler is a veterinarian in Modesto, Calif. Questions can be submitted to Your Pet in care of LifeStyles, The Modesto Bee, P.O. Box 5256, Modesto CA 95352.)