Housing is an ideal time to treat for worms and fluke to gain the maximum benefit, as animals are no longer at risk of becoming infected with stomach or gut worms, lungworm or liver fluke.

Effective treatment early after housing can prevent production losses until animals go back to pastures in the spring. External parasites can become more problematic in this period as the warm environment and close contact between animals helps lice and mites to thrive.

This is also a good time to review how animals performed on the parasite control plan over the grazing season.

Poor growth rates or scour in younger animals, and poor condition or milk yields in adults might indicate a need for adjusting the parasite control for the next grazing season.


Liver fluke can take 8-12 weeks to develop into adults once cattle are infected in the autumn, so at the time of housing immature liver fluke may be present.

Not all flukicides are effective against immature liver fluke and so timing and product choice are important to ensure that treatment is effective. The flukicides can be grouped into three main types depending on the targeted life stages of the liver fluke.

  • Flukicides that kill adult liver fluke only (eg albendazole, clorsulon or oxyclozanide) should be given at 10-12 weeks after housing if only one treatment is planned. To prevent production losses it might be preferable to treat earlier at housing and then follow up with a second treatment if the liver fluke burden is expected to be high. A dung sample can be taken eight weeks after treatment to check for fluke eggs as a guide to whether additional fluke treatments are needed.
  • Flukicides that kill juvenile fluke from six to eight weeks of age and adults (eg closantel, nitroxinil or rafoxanide) should be delayed until at least six to eight weeks after housing if only a single treatment is being given.
  • Flukicides that kill all stages including early-immature fluke (triclabendazole) can be given from two weeks after housing, usually only needing one treatment.
  • Each farm has a different level of risk for liver fluke so discuss any treatment plan with your veterinary practitioner, taking the farm history into account. Dung samples and abattoir reports from the Beef HealthCheck programme (www.beefhealthcheck.icbf.com) can help confirm the fluke status of the farm.

    Rumen fluke detected on a faecal sample does not usually require treatment unless the animals are showing clinical signs such as scouring or weight loss, or if there is a history of a rumen fluke problem on the farm. As there are limited treatment options available in Ireland for rumen fluke, discuss whether treatment is necessary with your veterinary practitioner.

    External parasites

    Lice and mites can become a problem in the housing period, causing scratching and hair loss in cattle. This can be so severe that it affects the animals’ welfare and performance.

    It is important to treat all animals that are in contact with each other, not only those that are showing clinical signs.

    For controlling chewing/biting lice, it is best to use an externally applied product such as a pour-on. Apply these products to clean, dry animals according to the package instructions.

    Injectable products are preferable for mites and sucking lice. If mites are present or if there is a heavy infestation of lice, a second treatment is usually needed.

    Ideally, get a diagnosis and identify which parasites are causing problems on the farm, particularly if a treatment does not seem to be working.


    Recent mild weather means that stomach and gut worms may be a problem in calves right up to housing and they may need dosing.

    Youngstock should be treated around housing with a product that is effective against dormant stomach worm larvae (Ostertagia) to reduce the risk of serious disease in late winter/early spring.

    Products containing levamisole (yellow drench) are not effective against these inhibited larvae. Instead use a product from the clear drenches (macrocyclic lactones) or certain white drenches (benzimidazoles). The clear drench will also treat against some lice and mites.

    Lungworm may still be a problem early at housing if youngstock were not recently dosed at grazing. Treatment for lungworm can prevent a parasitic pneumonia which could set animals back from reaching their performance targets. Other respiratory diseases should also be considered if animals are showing clinical signs such as coughing or breathing difficulties.

    Speak to your vet on the best approach to parasite treatments for your farm and always check the withdrawal period for any products used in finishing animals and dairy cows.

    Animal health tips

    Monitor calves and weanlings for any sign of pneumonia. Separate affected animals from the group at the first sign of illness. Get a diagnosis and treat accordingly. Vaccination and evaluating the ventilation in the shed can help prevent outbreaks.

    Liver fluke risk increases in autumn and winter and can affect all ages of cattle. Outwintered sheep are also at high risk of liver fluke. Treatment should be given where it is known to be present on-farm. Once housed, monitor animals for hair loss and itching which can be signs of lice and mites. Cattle may need more than one treatment over winter.

    The quality of colostrum can be improved by strategic vaccination of the dam and optimal nutrition over the dry period. Analyse the silage for nutritional content and plan for vaccinating cows ahead of calving to protect calves against scours.

    Hygiene at drying off and during the dry period is critical to prevent mastitis. Clip tails and rear udders to reduce the risk of new infections. Teat spraying three times per week is as effective in heifers as teat sealing and will also help train the heifers to the parlour. Identify cows with ongoing mastitis or a high SCC that have not been cured despite treatment. Some of these can’t be cured.

    These animals may be a source of contagious mastitis and should be culled to protect the herd.