7th June 2023

Mark Pass is the lead SQP for the Willows Veterinary Group and has recently joined the Control of Worms Sustainably (COWS) steering group. He has just completed an MSc thesis on lungworm and feels there is much that can be done to reduce the increasing number of cases being seen on dairy farms across the country…

Outbreaks of lungworm have continued to rise over the past 30 years and particularly in the 2020/2021 grazing seasons, affecting adult dairy cows and milking heifers. Bought-in cattle, unvaccinated animals and those with limited pasture larval exposure lack immunity and are vulnerable.

Worryingly, the parasite appears to be thriving more despite a large quantity of anthelmintics being used throughout the grazing season.

Gaining some immunity in early rearing, either by vaccination (the gold standard) or by allowing a trickle of exposure whilst using anthelmintics only when needed, is critical rather than a blanket approach every year.


Financial losses on a severe lungworm outbreak in growing youngstock range from £50 to £100 per animal due to weight loss, poor daily liveweight gain, poor future fertility and treatment costs. Depressed milk yield in adult dairy cattle can extend to £3 a cow a day. Literature reviews suggest affected cattle suffer noticeable loss of body condition up to 10% of bodyweight.


In my project, I wanted to explore stakeholder opinion on lungworm and current understanding of Dictyocaulus viviparus, the worm that causes lungworm.

Participants included 12 dairy farmers, four vets in practice, four Suitably Qualified Persons (R-SQPs) and two vets working in veterinary investigation centres and veterinary laboratories.

Eleven of the dairy farmers has seen lungworm in adult cows in the past two years and this was mainly from non-vaccinated herds.

Dairy farmers tend to be time poor and want simple solutions on lungworm control. However, the quality of advice currently on offer is very variable from vets and SQPs.

“I feel SQPs are very variable in their knowledge and vets don’t get involved enough,” said one of the investigative vets. “Some practices are very active, others are not. There is a massive range in the quality of advice given to the farmer.”

My research shows that dairy farmers receive most of their lungworm advice from SQPs (69%) with much less involvement from their vet (31%), except when the client’s Herd Health Plan is due.

The fact that SQPs cannot prescribe lungworm vaccinations and vets rarely prescribe anthelmintics is a part of the problem. There needs to be a more joined up approach.

Barriers to vaccination

Vaccine awareness was high in all interviewees and many recognised the issue of overuse of anthelmintics and some of the more worried stakeholders were starting to make changes.

Some are being driven by supermarket contracts with their increasing focus on sustainability and care for the environment.

Out of the 12 dairy farms, only three vaccinated annually and these only started following an outbreak. Two of these farms still saw outbreaks – but in bought-in adult dairy cows. Perhaps more vet or SQP input on biosecurity could have prevented these?

Cost, effort and timing were cited as reasons for not vaccinating.

“Cost is a big barrier,” said one farmer. ‘If it was a one-shot vaccine I would do it, there is too much aggro to dosing two doses and Ivermectin wormers are so cheap.”


Dairy farmers need their youngstock to grow without parasitic check, which has led to the overuse of anthelmintics.

And there is substantial evidence of lungworm advice falling in the gap between vets and SQPs. Both channels could be encouraged to engage a lot more.

I would recommend extra education on parasitology for both qualified and trainee vets and SQPs, along with more Continuing Professional Development (CPD) on lungworm and the role of immunity to prevent it.

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. Continuing such practices will ultimately create long term welfare problems in the future.

And finally, I would recommend that pharmaceutical companies and stakeholders such as vets and SQPs, alongside groups such as the British Veterinary Association (BVA) and the Animal Health Distributors Association (AHDA), consider how to manage the retail price of some very affordable pour-on and injectable anthelmintics, particularly ones with the active ingredient Ivermectin.

Mark’s study: ‘It’s a lung story.’ Analysing stakeholders perceptions of Dictyocaulus viviparus: An exploration of attitudes towards lungworm and understanding of effective sustainable control in dairy cattle, can be found in the Lungworm External Resources section of the COWS website.

(This article first appeared in OvertheCounter magazine – May 2023).