Gutworm and fluke risk increases as grazing gets into full swing

May Parasite Alert

The following information is informed by the May Parasite Forecast published by NADIS and is relevant for cattle producers in the UK only.

How young cattle develop PGE from Gutworm

Young cattle in their first- or second-season at grass are at highest risk of parasitic gastroenteritis (PGE) and resulting production losses, caused by gutworm species. Reduced growth and failure to make average daily live weight gain targets is the most common sign of a gutworm burden, which makes regular weighing a useful monitoring tool.

Early in the grazing season, susceptible cattle become infected by over-wintered larvae from eggs that were shed onto pasture during the previous year. These larvae die off by early summer, but by this time infected cattle may be shedding significant numbers of eggs, which will hatch and contribute to a rapidly increasing pasture challenge.

When to treat youngstock with anthelmintics?

It is important to treat youngstock with a suitable anthelmintic during the grazing season. Appropriately timed treatments will help to reduce contamination of the pasture as well as controlling worm-related production losses.

Making use of pasture not grazed the previous season, or moving animals to current season silage aftermath, will also reduce the worm burden in the latter part of the grazing season.

To prevent selecting for anthelmintic resistance, it is good practise to identify animals meeting growth targets and leave them untreated, while treating the remainder of the group. This ensures a mixed population of worm genetics are returned to the pasture without impacting the overall herd performance.

What actions to take for Gutworm?

  • Regularly weigh growing animals and track performance against targets, to identify individuals who may need worm treatments.
  • Target anthelmintic treatments only at those animals which are not meeting growth targets
  • Consider regular pooled faecal egg counts if you are unable to regularly weigh cattle, as this will provide some indication of the level of worm burden within the herd.
  • If using a 3-ML product such as IVOMEC® Classic Injection or Pour-On, or EPRINEX® Pour-On, and turning youngstock on to pasture grazed during the previous year, start monitoring and consider treating if required from three weeks after turnout and repeat after six to eight weeks. Always consult your vet or animal health advisor for guidance on the most appropriate treatment plan for your herd.
  • Move youngstock to ‘safe’ pasture or silage aftermath when available.
  • Consider your lungworm control strategy in conjunction with gutworm treatments, since these parasites may be controlled by some of the same anthelmintics.


Liver Fluke at grazing

Cattle that grazed at-risk pasture and were not appropriately treated for fluke at housing, or were out-wintered, may be carrying an adult (chronic) fluke burden. These animals will now be shedding fluke eggs onto the pasture and may also be experiencing production losses.

Though cattle may not exhibit obvious signs of a chronic fluke infection, they may not be making growth rate targets, may have impaired fertility, or in lactating cattle, may have a reduced milk yield.

What worm treatment for Liver Fluke 

To stop ongoing pasture contamination and prevent costly production losses from chronic fluke disease, infected animals should be treated with a selective flukicide that only targets the later stages of liver fluke, such as TRODAX®.

If a worm treatment is considered necessary at the same time, IVOMEC® Super is a suitable combination product.


What actions to take for Liver Fluke?

  • Monitor cattle for signs of chronic disease: weight loss or failure to meet weight gain targets, milk drop, anaemia, chronic diarrhoea, or weak calves born with little milk produced by the dam.
  • Consider diagnostic testing through pooled faecal egg counts. These can provide a useful indication of fluke infection status within a group of animals.
  • Consult abattoir kill sheets for information on numbers of livers condemned due to the presence of live liver fluke or evidence of liver fluke damage.
  • Consult your vet or animal health advisor for guidance on whether a treatment is necessary for some or all animals, according to the fluke status and individual requirements of your herd.
  • Avoid the use of triclabendazole products for chronic fluke treatments, and instead use a flukicide which targets only late-immature, and adult fluke.


Lungworm and youngstock

Lungworm disease is usually seen from mid-July onwards and where vaccination has not been used in susceptible herds, it is important to be alert for signs of disease.

Youngstock and adults with an unknown immunity status will be most at risk of disease. Vaccinated animals should still be monitored, especially later in the season if housing is delayed, since vaccine-derived immunity can be short-lived.

When developing a parasite control plan, remember that many products used for gutworm control also treat lungworm.

What actions to take for Lungworm?

  • Monitor cattle from July onwards when lungworm infectivity levels may start to increase.
  • Investigate any signs of persistent coughing in cattle as soon as possible.


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