Think di erently about lungworm in 2023

AMTRA Registered Animal Medicines Advisor (RAMA) Mark Pass, who works for the Willows Veterinary Group based in Cheshire, has recently completed his MSc thesis, which explored farming industry stakeholder attitudes to lungworm and the understanding of e ective, sustainable disease control. He believes the industry needs a reset.

“Mass prophylactic treatment of groups of animals with long acting anthelmintics must change. This is often the main driver of resistance in parasitic worm populations and continuing such practices will ultimately create long term welfare problems in the future,” he says.

Despite the continued, widespread use of long acting anthelmintics, lungworm incidence in cattle continues to rise, with many farmers seeing more disease in adult cattle and two-year-old dairy heifers once they have joined the milking herd. Mr Pass concludes that the increased prevalence of this costly disease is a worrying scenario, and is due potentially to a lack of herd/animal immunity to lungworm and under use of vaccination.

“Management practices, including grazing and housing, have changed signi cantly over recent years – with youngstock being housed a lot more than they once were. It is also more unusual for young cattle to graze at pasture for only a few months of the year, with the same trend seen with older lactating cows. Consequently, many cattle – and heifers, in particular – are often ill-prepared immunologically for a lungworm challenge when they enter the milking herd,” he says.

Vet Tom Warboys from Synergy Farm Health agrees. As a practising vet, he says he and his colleagues are seeing more lungworm outbreaks in cattle towards the end of the grazing season each year. “Unless they have had some opportunity to develop immunity, cattle that have been treated with long acting anthelmintics are particularly vulnerable to lungworm infection once the wormer cover wears o . This partly explains why we see so much disease around housing in the late autumn and early winter.”

Consequently, Mr Warboys says Synergy Farm Health is now encouraging all their cattle farmer clients to change their worming mindset. “Habitually worming cattle during the autumn and at winter housing (aiming to clean out residual gut or lungworm burdens) may give you peace of mind, but it’s time to think more sustainably,” he says.

He adds that wormer resistance is growing rapidly in the UK, particularly against ivermectins. In addition, there is increasing concern that widespread and continued use of valuable worming treatments is also harming vital insect populations in the dairy farming environment. “Ivermectins are fantastic products, but to preserve them we must use them more judiciously – and only when we absolutely have to,” he stresses.

“We probably underestimate the negative impact frequent worming with ivermectins has on soil health. For example, dung beetles are highly bene cial for farm productivity, but do not tolerate these wormers. Whilst moving 500x their own body weight of organic material, they reduce dung levels and therefore potential lungworm burdens left on pasture, improve soil health and make more grass available for future grazing. It is now time to think di erently about habitual worming and focus on making a sustainable parasite control plan for every farm,” he adds.

Synergy Farm Health is recommending cattle farmers work with their vet to adopt a ve-point parasite management plan in 2023, with the focus on reducing the need for expensive blanket worming when cattle are housed for the 2023/24 winter.

• Reduce stock vulnerability. Focus on immunity-based disease prevention. Disease-free cattle (e.g. free from BVD, IBR etc.), fed a high plane of nutrition and vaccinated against lungworm prior to turnout in 2023 are far less likely to need worming at all.

• Know your pastures. Assess pastures for risk, based on the stock that was grazing the ground during 2022. This could be done by colour-coding (e.g., red for previous grazing by youngstock, amber for adults and green for no previous grazing such as new leys, aftermath or grazing by other species) – and remember which elds contain lungworm.

• Adopt faecal egg counting. Worm egg counts are exceptionally useful indicators for group worming treatments.

• Assess cattle before any worming treatment. Liveweight gains, body condition scores, cleanliness of back ends, number of grazing seasons etc., are all there to guide you and are reliable indicators.

• Use the right drug for the bug. White or yellow drenches are usually adequate if you need to worm and do less damage to the environment.

However, Mr Warboys stresses that parasite control should not be considered in isolation.

He recommends that it should always form part of herd health planning when you can discuss it fully with your vet. FG