Worms and Parasites

Again, due to many questions with the aid of the forums the following information will help anyone with an internal parasite problem (many thanks to Aunt Sally and all the other forum contributors for this information).

Worms in chickens are of two general types

1.  Gut worms These live in the chicken’s digestive system and cause the hen not to thrive in many ways.  They can be picked up by your hen from other hens or from wild birds. Transmission is via faeces.

2.  Lung Worm or Gape Worm These live in the chicken’s respiratory system and can be very quickly fatal by suffocation.  They can be picked up by your hens eating slugs, snails and earth worms when free ranging, and from the faeces of infected birds.  Birds infected with these can be seen gaping and have respiratory distress symptoms.

Frequency of worming Most vets will recommend treating your chickens for worms every 4-6 months, but this is a decision for the individual to make.

The risk to chickens of contracting worms is very variable.  A small worm burden is natural for all birds and will usually not cause a problem.  If you just have a few hens in a run or in your garden the risk is quite small and wild birds is normally the only way they will get them, you may choose to worm these hens less frequently.  If the land you have your birds on has been used for hens for a long time the risks are higher.  The greatest risk is to large flocks of free range birds, you may choose to worm these more frequently.

Worming Products
There are a number of products available for use in treatment including: FlubenvetPanacurVerm-X and Diatomand some other unlicensed products which some chicken keepers use.

Flubenvet Intermediate is the most commonly used.  It is a white powder containing 2.5% w/w flubendazole and sold in 240g tubs.  There is now a 1% formulation which is intended for small flocks.   Flubenvet is a broad spectrum anthelmintic (acting to expel or destroy parasitic worms) and is for oral administration.  It is active against mature and immature stages of worms in the gastrointestinal and respiratory tract.  Flubendazole has no adverse effect on egg laying and hatchability and there is no need to withdraw eggs from consumption.  There is zero withdrawal on chicken eggs and poultry can be slaughtered for consumption 7 days after the end of treatment.

Dosage and Administration of Flubenvet There are a number of different methods of administering flubenvet.  The correct dose rate for the 2.5% formulation  is 1.2g Flubenvet Intermediate (about ~¼ teaspoon full) mixed into one kilo of feed and the chickens should be fed on this for 7 consecutive days.  Large birds will eat more feed, smaller ones will eat less and so they get the correct dose for their body weight.  It is a good idea to restrict treats to a very small amount in the afternoon while your hens are being wormed to ensure that they eat sufficient wormer.

Another method, if you only have a few birds, is to dose each bird individually each day for 7 days.  It is not possible to weigh out the correct dose on domestic scales.

2.5% formulation – use about 0.1- 0.2g per bird per day for 7 days.

1% formulation – use about 0.4 – 0.5g per bird per day for 7 days.

You will have to estimate the amount of powder needed from the volume of the 6g scoop.  Hide this in a treat such as a grape which the hens gobble up without hesitating  or add it to some porridgy food, mashed potato or whatever your girls like to eat.

The new 1% formulation, which does not require a mixing licence for purchase, should be used at 2.5 times the dose rate of the 2.5% formulation.

The 240g tub is 2.5% flubendazole
The 60g tub is 1.0% flubendazole


Panacur is a wormer more commonly used for cats and dogs and birds which are not to be used for meat or eggs soon after dosing.  If you take your hens to the vets for worming they will probably be given panacur (unless your vet specialises in chickens), one dose followed by another 10 days later if there are signs of worms is in the faeces. Vets recommend withholding eggs for 10 days after the last dose of panacur.

Diatom is another name for Diatomaceous Earth, it is 100% natural and is mined from the ground. It is comprised of the fossilised remains of diatoms (a type of algae ).  The diatoms have a hard shell made of ‘sharp’ non-crystalline silica, which does not decompose in the lakes, or sea where diatoms lived. Thus over long periods of time large volumes of diatoms are exposed on the surface of dried out lakes.  It can be added to animal feed at a rate of 5% to combat intestinal worms and can be considered an organic remedy as its action is physical rather than chemical but many chicken keepers have found it unreliable.  Its efficacy is debatable.

Ivermectin Eprinex

Ivermectin was originally developed to control worms in human in the developing world countries and found its way from there on to the animal market . It is not licensed for poultry although some vets recommend it and are happy to prescribe it.  You drop 2-3 drops on to skin on the back of the neck (like cat/dog flea drops), repeat after 3 days if the birds already have an infestation – it works for mites and lice too.  A preventative dose can be given once a month, or less frequently in the winter.  As it is not licensed for poultry opinions on egg withdrawal vary, some recommend an egg withdrawal period of 7 days and same say there is no need to withhold eggs although again as not licensed they cannot be sold.


Verm-X is popular with organic poultry flock keepers being based on totally natural ingredients.  It can be bought over the internet and is easy to administer in small doses. As a herbal formulation, Verm-X is available off the shelf and does not have to be signed for.  It’s efficacy is uncertain and we believe it has now activity against gape worm.


Some hen keepers add Apple Cider Vinegar to their chicken’s water.  But is should not be relied upon as a treatment for gut parasites !  It does have other health benefits.  Make sure you buy unrefined apple cider vinegar, the type sold for horses and not the sort from supermarkets.


Posted in My Chicken Diary

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