Intestinal Worms
There are several types of intestinal worms that can cause problems for backyard poultry flocks. The most common intestinal worms seen in Pennsylvania flocks are roundworms (Ascaridia spp.), cecal worms (Heterakis spp.), threadworms (Capillaria spp.), and tapeworms (Raillietina and Choanotaenia spp.).
The presence of a small number of worms does not typically cause clinical problems for poultry; however, if there are enough to be seen in excrement, you may need to treat ASAP.
How do Chickens get Worms?
Chickens and other poultry become infected by ingesting worm eggs from feed, water, litter, or grass contaminated by feces or through ingestion of an intermediate host (e.g. earthworms, grasshoppers, snails, slugs, flies, beetles, etc.) containing worm eggs. Worm eggs can survive in the environment for long periods of time and are resistant to killing by common disinfectants.
Sadly, intestinal worms in chickens are a common issue in backyard and free-range flocks. Luckily, low levels of parasitism don’t usually cause a problem. If the infestation becomes severe, however, worms can lead to significant losses of production, feed efficiency, and overall health.
The eggs and immature stages of many parasitic worms can live outside of the chicken host for a long time, possibly several years. Some parasitic worms spend part of their lifecycle in other creatures, such as earthworms, insects, slugs, or snails. Chickens pick up worms by eating dirt or litter contaminated with worm eggs or by eating small creatures carrying immature stages of worms.
Cecal Worms
Cecal worms, also called heterakis worms, reside in the ceca (pouches located where the small and large intestines come together) of chickens. They’re very common and generally don’t do much harm. The main worry with cecal worms is their ability to carry blackhead parasites, which are deadly for turkeys but rarely cause disease in chickens.
Eye Worms
Eyeworms (Oxyspirura mansoni) cause trouble only in warm climates, such as the southeastern United States, where the particular cockroach host lives. The parasite burrows under the third eyelid of chickens and other birds, causing eye to swell shut. As you can imagine, it’s irritating, and the bird does additional damage by scratching at the eye.
Roundworms
Roundworms (Ascaridia galli) are by far the most common parasitic worm of chickens. Young chickens with heavy infections of these big intestinal worms get skinny despite a good appetite. Chickens older than 4 months develop resistance to roundworms; the mature chicken’s immune system kicks out most worms. Every once in a while a roundworm will crawl into a hen’s oviduct and wind up inside an egg that she lays. This isn’t a human health hazard; it’s simply gross!
Gapeworm
Although in fact somewhat rare, the Gapeworm (Syngamus trachea) attaches to the lining of the windpipe in chickens and other poultry. If enough gapeworm get together in the windpipe, they cause a disease known as the gapes, named for the open-mouthed, distressed breathing of affected chickens. Young birds are more likely than older birds to have heavy infestations of gapeworm and get the gapes, which can be fatal. When chickens that have gapeworm ‘gape’, they typically make almost no sound at all when trying to breathe (unlike other respiratory illnesses which cause a honking or wheezing noise).
Tapeworm
Long ribbon-shaped tapeworms live in chickens’ intestines, where they don’t eat much or (usually) do much damage. In large numbers, tapeworms can cause birds to be skinny, but they’re rarely actually fatal. That said, they should be treated accordingly. Watch out for tapeworm segments in feces, such as the one below (courtesy Heritage Acres Market).
Threadworm
Some Capillaria, or threadworms, hang out in the crop or esophagus; others prefer to live in the intestinal lining. Heavy infections cause droopiness, pale combs, weight loss, and sometimes death.
Clinical signs associated with high worm burdens can include diarrhea, depression, reduced weight gain, weight loss, anemia, worms in eggs, and decreased egg production. However, many of these signs are not specific for worms so a definitive diagnosis should be made by microscopic examination of the feces for worm eggs and/or larvae.
Cecal worms rarely cause clinical issues for chickens but are especially problematic for turkeys as they can carry Histomonas meleagridis, the protozoal parasite that causes Blackhead. There is currently no treatment for Blackhead, so successful control of cecal worms is an important step for the control of Blackhead.
- Worms visible in feces
- Diarrhea
- Weight loss
- Anemia (pale comb and wattles)
- Worms in eggs (rare)
- Decreased egg production
Ideally, prior to de-worming, a fecal float test should be performed by your veterinarian or local lab. The presence of visible worms obviously does not require a float test, however may tell you what potential additional parasites your flock may be dealing with.
Although some vets do say that it doesn’t hurt things (and we tend to agree here), chickens actually do NOT require preventative de-worming.
Fenbendazole is the only product that is currently approved for treatment and control of roundworms (Ascaridia spp.) and cecal worms (Heterakis spp.) in chickens and turkeys in the United States.
Fenbendazole is available as a medicated feed labelled for use in poultry (Safe-Guard) or in a water-soluble formulation to be added to drinking water (Safe-Guard AquaSol) labelled for use in chickens. No egg withdrawal time is required for consumption of eggs or meat from AquaSol treated birds when administered according to label directions.
Additional medications available for use in deworming chickens include Valbazen (14 day egg withdrawal period), Levamisole (14 day egg withdrawal period), Pyrantel Pamoate Suspension (7 day egg withdrawal period). Both Valbazen and Levamisole (as well as Fenbendazole) should NOT be used for chickens while they are molting, as it has the potential to damage feather growth.
No egg withdrawal time is required for consumption of eggs or meat from AquaSol treated birds when administered according to label directions.
Our Treatment Recommendation
We recommend Safe-Guard AquaSol (Fenbendazole 20%) as it does not have an egg withdrawal period. Alternatively, you can also use the Safe-Guard for Goats version (Fenbendazole 10%), which is commonly available but has a 17 day egg withdrawal period and is not nearly as effective, as it doesn’t actually fully dissolve in water.
If using the Goat version, we recommend adding 3 ml (cc) per gallon to the chicken’s water — and ensuring that the ONLY water available to them contains the medication. It should be given for 5 consecutive days before switching back to unmedicated water. FYI, this version of Safe-Guard is not actually meant for drinking water and may not dissolve fully.
It is also strongly recommended that a second treatment be administered 10–14 days after the first treatment, in order to kill off any remaining worms that may have hatched after the initial treatment.
There is not an effective herbal or mineral remedy for chicken worms. Tobacco is far too toxic. Extensive research on diatomaceous earth (DE) has had very disappointing results; the substance has little if any effect against internal parasites — AND is a well known carcinogen and causes upper respiratory issues in poultry. Also, there is NO EVIDENCE that pumpkin has any effect either prophylactically or treatment-wise for worms. Sure, pumpkin is healthy, but it actually does nothing for or against intestinal worms.
Completely keeping your chickens away from worms isn’t possible. With good management on your part, worms may never cause illness in your flock. Good nutrition and a clean environment are very important in preventing heavy worm infections and illness due to parasites.
