5 Common Myths About Worms in Chickens
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Worms are common in backyard chickens, but there is still a lot of misinformation around how to recognise, prevent and treat them.
One of the biggest problems is that many chicken keepers either treat unnecessarily or assume their flock is worm-free because they cannot see anything obvious.
Here are five common worming myths worth clearing up.
Myth 1: If My Chicken Has Worms, I'll See Them in the Droppings
Usually, you won't.
Seeing an adult worm in a dropping can occur, particularly with larger worms such as Ascaridia galli, but it is not a reliable way to determine whether a chicken has a worm burden.
Most of the time, what we detect in droppings are microscopic worm eggs, which cannot be seen with the naked eye. Some parasites may also be present without producing anything obvious for an owner to notice.
So visually checking droppings and seeing no worms does not mean your chickens are worm-free.
A fecal egg count (FEC) is a much more useful way of monitoring gastrointestinal worms. It allows us to look for parasite eggs microscopically and estimate the level of shedding within the flock.
Myth 2: I Keep the Coop Clean, So My Chickens Can't Get Worms
Good hygiene absolutely helps, but it cannot completely prevent worms.
Many worm eggs are remarkably resistant in the environment and can persist in soil for long periods. Free-ranging chickens are also continually exposed to contaminated ground.
Some parasites have indirect life cycles, meaning another animal acts as an intermediate host. Chickens can become infected when they eat insects, earthworms, slugs, snails or other hosts carrying infective parasite stages.
Good parasite management can include:
- Regular removal of accumulated droppings
- Keeping housing clean and dry
- Avoiding overcrowding
- Rotating heavily used areas where practical
- Managing intermediate hosts where relevant
- Monitoring parasite burdens with fecal testing
Cleanliness reduces parasite pressure, but it cannot make a free-ranging environment parasite-free.
Myth 3: A Messy Bottom Means My Chicken Has Worms
A dirty backside tells you that something may be affecting the consistency or passage of droppings. It does not tell you what the underlying problem is.
Abnormal droppings can occur with many conditions, including:
- Coccidiosis
- Enteritis
- Dietary changes
- Stress
- Reproductive disease
- Liver disease
- Some infectious diseases
- Gastrointestinal parasites
Treating every chicken with diarrhoea for worms can mean the actual problem is missed.
It also exposes parasites to worming medications unnecessarily, which contributes to the development of anthelmintic resistance.
Diagnose first, then treat what is actually there.
Myth 4: Garlic and Diatomaceous Earth Are Natural Wormers
Garlic and diatomaceous earth (DE) are frequently promoted as natural alternatives to conventional worming medications.
The problem is that the evidence does not support relying on either product to treat an established worm burden.
Garlic has been investigated for potential antiparasitic properties, but available research does not provide good evidence that feeding garlic to chickens will reliably eliminate gastrointestinal worms.
Diatomaceous earth has a similar problem. Despite its popularity in backyard farming, there is insufficient evidence that feeding DE provides reliable control of internal parasites.
There is also another consideration with DE: dust exposure. Diatomaceous earth is a fine particulate material and inhalation should be minimised for both birds and people.
Natural does not automatically mean effective or harmless.
If a chicken has a clinically significant worm burden, use a treatment demonstrated to work against the parasite involved.
Myth 5: The Best Wormer Is the One With Zero Egg Withholding
Egg withholding is understandably important to backyard chicken owners. Nobody enjoys throwing eggs away.
But withholding periods should not be the only factor considered when selecting a worming treatment.
The first question should be:
Will this treatment effectively treat the parasite my chickens actually have?
The route of administration also matters.
Medication delivered through drinking water relies on birds consuming an adequate amount of medicated water. This can become unreliable if chickens have access to puddles, ponds or other water sources.
In-feed medications also rely on adequate and relatively consistent consumption. Simply sprinkling medication over pellets may not distribute the drug evenly enough to ensure every bird receives the intended dose.
For small flocks, individually administered treatments can sometimes provide much greater dosing accuracy.
The best treatment depends on the parasite, flock, medication, administration method and regulatory requirements around meat and eggs.
Test Before You Worm
Where practical, we recommend using fecal egg counts rather than automatically worming chickens on a fixed schedule.
FEC testing can help determine:
- Whether worm eggs are present
- Which parasite groups are involved
- Whether the burden warrants treatment
- Which treatment may be appropriate
- Whether parasite management is working
For many backyard flocks, testing two to three times per year provides useful routine monitoring. Higher-risk flocks may benefit from more frequent testing.
Testing after treatment can also be valuable when you need to determine whether a wormer has actually been effective.
What About Routine Preventative Worming?
Routine worming without knowing whether parasites are present is generally not our preferred approach.
Repeated unnecessary exposure to worming medications increases selection pressure for anthelmintic resistance, where surviving parasites become progressively less susceptible to the drugs used against them.
Rather than routinely rotating wormers simply for the sake of changing active ingredients, treatment should ideally be based on parasite identification, treatment efficacy and veterinary guidance.
Likewise, not every worm treatment automatically needs to be repeated twice. Whether retreatment is required depends on the parasite involved, the medication used and its activity against different life stages.
A blanket worming schedule cannot account for those differences.
A Better Approach to Worm Control
Good worm management isn't about eliminating every parasite from the environment. In free-ranging chickens, that is usually unrealistic.
Instead, the aim is to keep parasite burdens below levels that affect health and welfare while using worming medications responsibly.
That means combining good hygiene, sensible stocking densities, environmental management, routine monitoring and targeted treatment when necessary.
If you're unsure whether your flock needs worming, start with a Fecal Egg Count.
It is much easier to make a sensible treatment decision when you know what you're actually dealing with.
Written by Dr Sam Hurley, BSc, BVSc, MAHM
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References
Thapa S, Thamsborg SM, Wang R, Meyling NV, Dalgaard TS, Petersen HH, Mejer H. (2018). Effect of the nematophagous fungus Pochonia chlamydosporia on soil content of ascarid eggs and infection levels in exposed hens. Parasites & Vectors, 11, 319.
Barnard G, Worku M, Ahmedna M. (2009). The effects of diatomaceous earth on parasite infected goats. Bulletin of the Georgia National Academy of Sciences, 3, 129 to 135.
Fernandez MI, Woodward BW, Stromberg BE. (1998). Effect of diatomaceous earth as an anthelmintic treatment on internal parasites and feedlot performance of beef steers. Animal Science, 66, 635 to 641.
Singh N, Shalini. (2000). Studies on the anthelmintic activity of Allium sativum (garlic) oil on common poultry worms Ascaridia galli and Heterakis gallinae. Journal of Parasitology and Applied Animal Biology, 9, 47 to 52.