Worming chickens: spot the worms, test, and treat when it is needed

According to the MSD Veterinary Manual, several groups of worms affect chickens. Only a vet can say which ones are involved:

Large roundworms (Ascaridia)

The most common. In large numbers, they slow growth and can block the gut.

Caecal worms (Heterakis)

Not very harmful in themselves, but they carry the parasite that causes blackhead (histomoniasis), a serious disease.

Capillary worms (hairworms)

They settle in the crop, oesophagus or gut; a heavy infestation can be serious.

Gapeworm (windpipe worms)

They live in the windpipe and lungs, and are most dangerous for young birds: the hen gapes, chokes and shakes its head.

Tapeworms

They need an intermediate host: beetles, flies, slugs or snails.

Some worms pass directly from hen to hen: according to the MSD Manual, roundworm eggs passed in droppings become infective in about 10 to 12 days, then hens swallow them while pecking. Others arrive through the small creatures hens eat: earthworms for caecal worms, some capillary worms and gapeworm; slugs, snails and insects for tapeworms.

Damp, built-up, poorly kept litter encourages both worm eggs and these small hosts.

The vet looks for worm eggs under the microscope in a sample of droppings. RSPCA Australia advises these tests two to four times a year, to find out which parasites are present before choosing a treatment. According to the MSD Manual, finding no eggs in a sample does not prove there are no worms, and the test cannot always tell which worm is involved.

• Ask your vet how to collect and store the droppings sample.
• Tell your vet about any worm seen in droppings: they can also test for tapeworms.
• Write down the date and the result: they will guide the next decision.

For the MSD Manual, worm control relies first on management and hygiene. For free-ranging hens, moving them to fresh ground is the only way to act on the soil, and its effect is temporary.

• If you can, split the run into two areas and rotate them, to rest the ground.
• Keep litter dry, and replace it before it builds up and gets damp.
• Use a feeder rather than scattering food on the ground.
• Keep hens of different ages apart when new birds arrive, as the MSD Manual advises.

Opinions vary: the Royal Veterinary College (RVC) exotics service advises worming at least twice a year, while the MSD Manual recommends keeping treatment for heavy infestations with signs. Worms resistant to wormers have been reported, and worms soon come back after treatment if the run stays contaminated. Your vet decides based on test results and your hens’ age and way of life.

Once you and your vet have agreed how often to test or worm, MyArk turns it into a recurring reminder shared by the household. The health record serves as your treatment log: date, the product you noted, end of the egg withdrawal period.

• A reminder at the interval agreed with your vet, for tests as well as treatments
• Every treatment recorded in the health record, with the date
• The end of the egg withdrawal period, noted so nobody gets it wrong
• Test results kept in the same place