Signs of Worms in Chickens

By John Walker · Backyard chicken keeper in Dallas, Texas since 2017

Signs of worms in chickens are easy to miss, because a light worm burden often causes no visible change at all, and the first clues are usually vague: a paler comb, a hen that eats well but stays thin, droppings that turn loose, and a slow fall in egg numbers. Worms are internal parasites that live in the gut, and the common backyard types are roundworms, hairworms, and tapeworms, each with its own habits and signs. A heavy burden can stunt young birds, weaken layers, and in rare cases block the gut. This guide covers the symptoms to watch for, how the faecal float test confirms worms, and what to do next, including when a vet visit matters more than a wormer.

What are the signs of worms in chickens?

The signs of worms in chickens are a pale comb and wattles, steady weight loss despite a good appetite, loose or watery droppings, and a drop in egg laying. These signs appear gradually as the worm burden grows. A light burden often shows nothing at all, which is why worms are often found by testing rather than by looking.

The pale comb is usually the first thing keepers notice. Worms feed on the bird's nutrients and, in some species, on blood, so the bird becomes anaemic and the comb fades from bright red to pink or pale. The bird may also look dull and stand with its feathers fluffed up, spending more time resting and less time scratching and foraging.

Weight loss is the next clue, and it is easy to miss in a feathered bird. Pick the bird up and feel the breastbone: in a wormy bird the breast muscle feels thin and the keel bone feels sharp, even though the bird is eating normally. Young birds with worms grow slowly and may stay small, with poor feathering and a stunted frame compared with their hatch mates.

Egg laying falls too. A laying hen with a heavy worm burden may stop laying, lay smaller eggs, or lay eggs with pale yolks and thin shells, because the worms are taking the protein and minerals that would have gone into the egg. Droppings may turn loose, foamy, or greenish, and in heavy roundworm cases you may see long white worms in the droppings, although most worms are never seen.

Types of worms that affect chickens

Chickens carry several types of internal worm, and the three that backyard keepers meet most often are large roundworms, hairworms, and tapeworms, each living in a different part of the gut and causing slightly different trouble. Knowing which type you are dealing with matters, because not every wormer kills every worm.

Large roundworms are the most common. They live in the small intestine, grow up to several inches long, and are the worms most often seen in droppings. A few roundworms cause little harm, but a heavy burden can block the gut, stunt growth, and in young birds cause death. Their eggs pass out in the droppings and become infective in the soil after a few weeks, which is why birds on the same ground keep getting reinfected.

Hairworms, also called capillary worms, are thin, thread-like worms that live in the crop, the gullet, and the intestine. They are harder to spot, because they are small and rarely appear in droppings, but they can cause serious damage: birds lose weight, drink a lot, and develop a swollen, pale crop, and a heavy burden in the gut causes diarrhoea and wasting.

Tapeworms are flat, segmented worms that live in the intestine and need an intermediate host, such as a beetle, fly, slug, or earthworm, to complete their life cycle. Chickens pick them up by eating the infected insect, so tapeworms are common in free-range flocks. You may see small white rice-like segments in the droppings, and heavy burdens cause weight loss and poor laying. Gapeworms, which live in the windpipe and cause gasping, are rarer but worth knowing about, because a gasping bird is often misdiagnosed as having a respiratory infection.

The faecal float test: how to confirm worms

The faecal float test is the reliable way to confirm worms in chickens, and it works by mixing a fresh dropping sample with a salt solution so that worm eggs float to the top, where they can be counted under a microscope. It is the test vets use, and it beats guessing from symptoms every time.

To collect a sample, take fresh droppings from several birds in the flock, not just the sick one, and put them in a clean, sealed bag or tub. Keep the sample cool and get it to the vet within a day. A pooled sample from five or six birds gives a good picture of the whole flock, which matters because worms are usually a flock problem, not a single-bird problem.

At the laboratory the sample is mixed with a dense salt or sugar solution, and the worm eggs float to the surface and stick to a cover slip, where they are counted under a microscope. The count is reported as eggs per gram, and it tells the vet whether the burden is light, moderate, or heavy, and which type of worm is present, because roundworm, hairworm, and tapeworm eggs all look different.

The test is cheap, quick, and it prevents two common mistakes: worming a flock that does not need it, and worming with the wrong product for the worm that is actually present. Ask your vet for a faecal float test before you worm, and again a few weeks after worming, to check that the treatment worked. If your vet does not see poultry, a state diagnostic laboratory or a farm vet can usually run the test.

Signs of worms in chickens vs other illnesses

The signs of worms in chickens overlap with several other common problems, so a pale comb and weight loss do not automatically mean worms, and treating for the wrong cause wastes time while the real problem gets worse. The three look-alikes worth knowing are coccidiosis, mites, and moulting.

Coccidiosis is a gut parasite too, but it is a single-celled organism rather than a worm, and it usually strikes young birds with bloody or rust-coloured droppings, hunched posture, and sudden deaths. Worms are slower: weeks of wasting and a pale comb, with droppings that are loose rather than bloody. A faecal test separates the two, and the treatments are different.

Mites and lice also cause pale combs and poor condition, because they feed on blood and irritate the skin, and a bird with a heavy mite burden will look dull and lay fewer eggs, just like a wormy bird. The difference is on the skin: part the feathers around the vent and under the wings and look for tiny moving specks or clusters of eggs at the feather shafts. Worms leave no sign on the skin.

Moulting causes a drop in laying and a scruffy look, but a moulting bird keeps a good weight and a reasonably red comb, and the feather loss follows a pattern. A bird that is losing weight, has a pale comb, and has loose droppings outside of moult season is more likely to have worms, and a faecal float test will settle the question in a day.

What to do when your chickens have worms

When your chickens have worms, the first step is a faecal float test to identify the worm type, then a wormer that kills that type, given at the label dose, with the egg withdrawal period observed. Worming without a diagnosis is guesswork, and guessing with drugs is poor practice.

Your vet can recommend a product for the worm type found. Fenbendazole and albendazole are broad wormers used in poultry, and flubendazole is used in some countries, but the legal status and withdrawal periods differ by country, so follow the label for your country and your vet's advice rather than a forum post. Some wormers do not kill tapeworms, so a tapeworm diagnosis needs a different product, which is another reason the test matters first.

Treat the whole flock at the same time, because untreated birds will reinfect the treated ones within days. Repeat the dose after the interval on the label, usually ten to fourteen days, to kill worms that were eggs at the time of the first dose. During treatment, collect and discard eggs for the withdrawal period on the label, and do not eat or sell them.

Clean the housing while you treat. Remove old litter, clean feeders and drinkers, and move the birds to fresh ground if you can, because worm eggs survive in soil and litter for months. Rotate the run, keep the ground dry, and avoid overcrowding, because damp, crowded ground is where worm eggs thrive. A follow-up faecal test a few weeks later shows whether the treatment worked.

Worm type	Main signs	Seen in droppings?
Large roundworm	Weight loss, pale comb, fewer eggs	Yes — long white worms
Hairworm	Wasting, loose droppings, swollen crop	Rarely — eggs need a test
Tapeworm	Weight loss, poor laying	Yes — rice-like segments
Gapeworm	Gasping, head shaking, open beak	No — lives in the windpipe

Preventing worms in your flock

Preventing worms in chickens is mostly about managing the ground they live on, because worm eggs are picked up from soil, litter, and droppings, and a dry, rotated run breaks the cycle. No prevention is perfect, but good management keeps burdens low enough that birds stay healthy without constant worming.

Rotate the run when you can, and rest ground for several weeks so that worm eggs in the soil die off in sun and dry air. Keep the run dry: fix leaking drinkers, avoid muddy patches, and use a deep litter that stays dry on top. Damp, shaded, crowded ground is where worm eggs survive longest.

Keep feeders and drinkers raised off the ground so droppings cannot fall into them, and clean them weekly. Do not feed on bare soil where birds have been defecating, and pick up droppings from the coop floor regularly. Young birds are the most vulnerable, so brood chicks on clean ground away from adult droppings.

Test rather than worming on a schedule. A faecal float test once or twice a year, and whenever birds look pale and thin, tells you whether worming is needed and which product to use. Routine worming without testing builds drug resistance, wastes money, and throws away eggs during withdrawal for no benefit.

Please note: This guide is general information, not veterinary advice. Worming medicines are drugs with withdrawal periods; follow the product label and talk to a poultry vet if birds are very sick.

Sources: University of Georgia Extension, internal parasites of poultry and poultry.extension.org.

Related tools and guides

For more on the same topic, see Bumblefoot in Chickens.

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