Our Privacy/Cookie Policy contains detailed information about the types of cookies & related technology on our site, and some ways to opt out. By using the site, you agree to the uses of cookies and other technology as outlined in our Policy, and to our Terms of Use.


Signs of Worms in Chickens

| Updated September 26, 2017

Various types of worms can infest your chickens. It's likely members of your flock harbor a few intestinal parasites, but signs of worms generally appear only in seriously infested birds. If your chickens show signs of worm infestation, deworming is necessary. Many backyard chicken-keepers deworm their flock twice a year -- in spring and fall -- to keep intestinal parasites at bay.

Signs of Worms

While signs of worms vary on the primary type of parasite infecting your birds, chickens with worms share similar signs of infestation. These include:

  • General lack of thriftiness
  • Lowered egg production
  • Poor growth in young birds
  • Poor feather quality
  • Diarrhea
  • Emaciation

The first sign that a chicken is suffering from a severe worm infestation could be a dead bird. That's likely due to intestinal blockage. Worms also suppress the bird's immune system, so other ailments may appear in the flock.

Types of Chicken Worms

  • Large roundworms: Probably the most damaging of chicken worms, the large roundworms pass between birds by consumption of the worm eggs shed in the feces of infested chickens. Free-range chickens also pick up large roundworm eggs when ingesting earthworms or grasshoppers. 
  • Small roundworms: While less threatening to chickens than large roundworms, small roundworms cause their share of problems, especially in the bird's intestinal tract. Also known as threadworms, small roundworms are passed between birds in a similar fashion to large roundworms. 
  • Tapeworms: Because tapeworms are host-specific, a chicken tapeworm won't affect a duck, and vice versa. Free-range chickens may pick up these worms by ingesting intermediate hosts, such as snails and various insects. A bad infestation causes malnutrition. 
  • Cecal worms: While common in chickens, these worms generally cause a  bird little harm. 

Chicken Deworming

Take fecal samples to your vet so she can determine what is infesting your flock. Even if you don't have a vet for your chickens, a small animal vet can do this testing, since many of these parasites infect cats and dogs. Your vet can tell you what type of dewormer to use on your flock based on the types of worms and the worm count.


  • Even though only a few of your birds may show signs of worms, you must treat the entire flock. With many chicken dewormers, you have little choice even it wasn't a good husbandry practice, since the medications are added to either the feed or the water.

Although the number of dewormers permitted for use in chickens is limited, your vet may recommend using a dewormer off-label. Common chicken dewormers include:

  • Piperazine: This dewormer eradicates large roundworms and is given to chickens in the waterer or by direct administration into the bird's mouth.
  • Levamisole: This medication controls small roundworms and cecal worms. It can work to eradicate tapeworms to some degree. Levamisole is mixed into the drinking water.
  • Hygromycin B: Mixed in feed, this dewormer controls large roundworms and cecal worms.

Worm Prevention

Keeping your flock's coop and pen as clean as possible is the best way to prevent warm infestation. That means regularly removing feces and thoroughly cleaning feeders and waterers. Keep wild birds out of your flock's pen, and don't overcrowd your chickens.