Worms in Chickens

Worms in Chickens featured image

by Kim A.

Chicken Worms: Symptoms, Treatment, and Prevention

Upon hearing the phrase “worms in chickens,” most people get a little squigged out. Right?  I know I do.  But what if I use the word helminth?  Nematode?  Annelid?  Do these words sound better?  No?  And, why?  Well, because they all mean worm. 

Yes.  Those wiggly, squiggly, squirmy things.  But not the ones that dangle on the end of our fishing poles, or the ones that get cozy in our garden beds.  The worms I’m talking about are parasitic worms – the ones that can infect your backyard chickens and cause problems for your home egg and meat production.

First, you should know that worms are a very common parasite in backyard chickens.  And at low loads, chickens are just fine.  It’s when intestinal parasite loads become severe that you will start to see the effects on your flock.  Worms in chickens are a hot topic. 

In fact, a recent review of online searches inquiring about chicken worms showed that there were almost 10,000 requests for more information — does my chicken have worms, what are the types of worms parasitizing my chickens, how do I identify them, and how do I get rid of worms in my chickens?  So, we are here to provide answers to these questions and more.

What worms are found in chickens? 

What are worms? Worms are one of two types of common internal parasites in chickens. (Protozoa are the second and will not be discussed in this article.)  There are several groups of parasitic worms that can infect your flock:

  • Flatworms (platyhelminths)
  • Thorny-headed/Spiny-headed worms (acanthocephalans)
  • Tapeworms (cestodes)
  • Roundworms (nematodes)
  • Flukes (trematodes)

Although acanthocephalans and trematodes can infect chickens, cases of this type are very rare.  So, let’s focus on the most common worms that can parasitize your chickens.  They are tapeworms and roundworms: 

  1.  Large Roundworms (Ascaridia galli) – very common in chickens; easily seen with the naked eye measuring approximately 1-2 mm in width and 1 to 4.5 inches in length; and because they can occasionally travel up to the hen’s reproductive tract, these worms can be found inside eggs.
  2. Cecal Worms (Heterakis gallinarum) – also of the class Nematodes; a roundworm; found in the cecum of chickens; causes no damage to chickens, but parasitized chickens can cause blackhead disease in turkeys. This is why you may have heard that you should not co-house your chickens and turkeys or range in the same areas.
  3.  Capillary (Thread) Worms (Capillaria spp.) – capillary worms are thin, thread-like worms that affect different parts of the chicken. In the crop and esophagus, they cause thickening and inflammation of the mucus membranes; in the lower part of the intestine in the lining, the eggs can cause inflammation, hemorrhage and breakdown of the intestinal mucosa; very difficult to see with the naked eye – usually only seen upon necropsy; become an issue when using deep bedding practices; can cause death when infestation is severe.
  4.  Tapeworms (Davainea proglottina) – these worms live in the chicken’s intestinal tract; they are segmented, long worms that appear flat or ribbon-like; can grow to more than 5 inches in length. Infections can lead to emaciation because these worms anchor themselves to the walls of the small intestine with hook-like mouths.
  5.  Gapeworms (Syngamus trachea) – also known as forked worms because the male and female are locked together forming a “Y;” appear red; infest the trachea; causes “gaping” or “gasping” in chickens with a heavy infestation; can grow up to 1 inch, blocking the trachea.

How do I tell if my chickens have worms?

Signs of a high worm burden in your chickens may include weight loss, diarrhea, pasty vent, pale comb, decrease in egg production, worms in the eggs, and behavior changes.  Note that these signs do not necessarily indicate that your flock has worms.  But, overlooking any of these signs can potentially lead to the death of your birds.

Worms can be diagnosed in several ways.  If your chickens have a significantly high worm load, tapeworms and roundworms can be seen in the feces.  As noted above, tapeworms and roundworms tend to be at least an inch in length implying that the term “roundworm” may be a misnomer for these worms.  Therefore, you may see small segments of these worms upon direct examination.

You can also take a fresh fecal sample to your veterinarian.  They can perform a fecal floatation or smear test to determine if there are worm eggs present in the gastrointestinal tract (GI).  If you are concerned about either respiratory or GI worms, you can also have your veterinarian perform a necropsy (post-mortem examination) to collect mucosal samples of the tissue in question.  This can also be a definitive way to gauge the overall health status of the rest of your flock.  PCR and loop mediated isothermal amplification (LAMP) assays can also be of use in determining the species of worm.

How did my chickens get worms?

Chickens can ingest worms from their feed, water, bedding, contaminated grass, or intermediate hosts like earthworms, grasshoppers, flies, beetles and slugs.  They can also be introduced via contaminated equipment like rakes, shovels, buckets, feeders and waterers.  You can introduce worm eggs via your shoes, as well. And don’t forget, worm eggs can survive in most environments for a long time.  Eggs are also not very susceptible to disinfectants or pesticides.

How do I prevent, treat, and control worms in my chickens?


As mentioned at the beginning of this article, low worm loads in your chickens will not cause significant problems in your flock.  However, most of us raising chickens for egg or meat production cringe at the thought that our chickens could have worms.  So, there are basic measures that you can use to prevent chicken worms:

  Keep your coop and chicken yard clean

  • Bedding needs to be clean and dry and changed regularly
  • Clean and sanitize the coop before introducing new poultry
  • Clean waterers daily
  •  Avoid overcrowding
  • Control flies in and around your coop.  They can be a host for tapeworms.

  Practice good biosecurity

  • Clean and sanitize any equipment that you use in and around the coop regularly
  • Get your chickens moving – if your flock has had a worm infestation, move them to new land through use of a mobile coop or chicken tractor.  This gives you an opportunity to clean the infested area.  Manure buildup increases the eventuality that you will have a significant load of parasites, viruses, and bacteria.  And, if your chickens are mobile (free ranging or in a moveable coop, you can incorporate them into your rotational grazing.
  • Quarantine new chickens before exposing them to your flock.  This gives you the opportunity to ensure that your new birds are healthy before adding them to your coop.
  • Prevent wild birds and animals from getting to your chickens.  Wild birds can be heavily infested with all sorts of pathogens.  Netting, hardware cloth, and chicken wire can help minimize exposure.
  • Monitor your flock!  Interacting with your chickens regularly allows you the opportunity to see who is thriving and who is not.
  • Wash your hands after handling anything in the coop. Sanitize your boots between livestock areas.


If you are monitoring your flock for signs of worm infestation, try to identify the worm type before determining the type of treatment to use.  Remember, you do not want to randomly administer dewormers as this practice can lead to parasite resistance.  You want to choose the right treatment and have a targeted treatment plan where you only treat when it is determined that your flock has a high worm load.  Again, relying on a calendar-based treatment regimen can lead to worm resistance in your chickens. 

It is important to note here that there are few approved treatments available for deworming your chickens.  However, there is the option for your veterinarian to prescribe a drug not approved for chickens specifically yet can be used off-label or extra-label for effective results.


Having addressed worm resistance, there is only one approved deworming drug for use in chickens for roundworms.  Fenbendazole* under the name Safe-Guard® AquaSol (Merck Animal Health, Intervet Inc., Rahway, NJ) is added to the flocks’ drinking water.  It has only been shown to be efficacious against Ascaridia galli and Heterakis gallinarum, however.  As with all drugs, fenbendazole should only be administered as directed. There is no meat or egg withdrawal period when using this dewormer properly.

Extra-label, and only under the direction of a veterinarian, fenbendazole has been shown to be effective against some capillary worm species.

Extra-label dewormers (requires a prescription from a veterinarian)

Extra-label Dewormers (requires a prescription)
DrugBrand NameTreatsEgg/Meat Withdrawal
Fenbendazole*Safe-Guard® AquasolRoundworms, Gapeworms, and other Ascaris spp.None
Pyrantel pamoateNemex, StrongidRoundworms, Capillary wormsNo information found
AlbendazoleValbazenRoundworms, Cecal worms, Capillary worms, TapewormsNo information found
IvermectinIvomecRoundworms, Cecal worms, Capillary wormsNo information found
LevamisoleProhibitRoundworms, Cecal worms, Capillary wormsNo information found

Natural/Homeopathic Treatments

Note that not much research has been done on the use of medicinal herbs, homeopathic or naturopathic treatments.  There have been a few that showed promise, but these studies had small cohorts and were limited in their scope.

  • Garlic in drinking water
  • Turmeric added to feed
  • Papaya seed extract and powder
  • Diatomaceous earth as a food additive
  • Pumpkin seeds
  • Various essential oils


Controlling worms starts with prevention.  Preventing chicken areas from becoming dirty and allowing conditions where worms or their eggs can thrive will significantly decrease your flock’s susceptibility to worm infestation. 

Ensuring that your chickens are receiving the right nutrition with access to clean water will allow their immune systems to be able to manage low grade infestations.  Treating your chickens with approved or veterinary prescribed deworming drugs only when you and your vet have identified the type of worm infecting your chickens is recommended. 

Follow deworming instructions to ensure that each chicken is getting the necessary dose to effectively rid your birds of worms and their eggs.  Do not over treat or treat based on an arbitrary calendar timeline whether you see evidence of worms or not.  This method leads to worms developing resistance to the drugs you are using to treat.

One last note should be mentioned.  You cannot become infected with the worms mentioned above as these worms are species-specific.  However, chicken feces can carry bacteria, like Salmonella.  And chickens can carry a host of other pathogens that can affect you.  So, make sure to practice good personal hygiene by washing your hands well and frequently when working with or being around your flock.

Some key things to consider regarding chicken worms – starting with healthy animals and using good animal husbandry practices can help mitigate the potential for worm infestation in your chickens.  The worms that infect chickens in low numbers usually do not affect the overall health of the flock.  However, prolonging treatment when worm burdens are high can lead to poor health and even death.

There are effective deworming treatments, but they must be used correctly according to product directions or under the advice of your veterinarian.  Dewormers should only be used when necessary to limit the potential for drug resistance.

So, here’s to no worms in your chickens. Let’s keep those creepy crawlies at bay.   And may the only worms you deal with be the ones that help create great compost for your garden or help you hook that big one!

About the Author: Kim A. is a retired researcher who specialized in the study of viruses. After many years in California, she and her husband moved to the mountains of Montana where they live off-grid, fully embracing a sustainable lifestyle. Now, she channels her passion for research into freelance writing. Kim and her husband take pride in breeding and raising registered Scottish Highland cattle and registered Nigerian Dwarf goats. She also enjoys gardening, cheesemaking, and loves the homesteading life.

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