Promoting Sustainable Control of Cattle Parasites

Things to do now

Always read the label and ask advice from a vet, vet pharmacist or SQP before deciding which product to use.

Things to do now

Always weigh cattle or use a weigh band to calculate the correct dose for each animal

Things to do now

Check meat and milk withdrawal periods for each product before administration

Things to do now

For advice on managing parasite infections in sheep visit www.scops.org.uk

What is COWS?

Control Of Worms Sustainably (COWS) is a voluntary initiative aiming to provide the best available, evidence-based information to the beef and dairy cattle industries in relation to the sustainable control of both internal and external parasites.

COWS funders

As a voluntary initiative, COWS is kindly funded by: AgriSearch, AHDB, AHDA, AHDB Beef & Lamb, AHDB Dairy, AMTRA, HCC, NFU, NOAH and QMS. COWS also works closely with SCOPS.

Latest News

VMD to conduct research on anthelmintic prescribing practices

1st September 2026

The Research, Innovation, Sustainability and Evidence team at the Veterinary Medicines Directorate (VMD) is exploring stakeholder perceptions of anthelmintic prescribing and anthelmintic resistance in grazing livestock. The research will focus on SPQs/RAMAs who prescribe wormers for livestock, specifically sheep and cattle, as well as equines. Interviews will follow a semi-strucured format, enabling participants to discuss ... Continued

COWS experts deliver lungworm facts and actions in popular webinar

21st August 2026

COWS steering group members, farm vet Rob Howe, Moredun Research Institute principal research scientist Dr Dave Bartley and farm vet Anuschka Marsman, reflected on all aspects of lungworm disease on a recent webinar hosted by the Responsible Use of Medicines in Agriculture (RUMA). This was held in conjunction with the British Veterinary Association (BVA) and ... Continued

Loss of Huskvac a serious concern and threat to sustainable parasite control

10th August 2026

The announcement that Bovilis® Huskvac, the UK’s only licensed lungworm vaccine, will be withdrawn from the market from 2027 comes at precisely the wrong moment for UK cattle farming. Cattle vet and COWS member Rob Howe has written to the editor of the Veterinary Record to air the industry's concerns. Resistance We now know that ... Continued

COWS Funders

COWS Terms of Reference

Things to do in the summer

Steps you should be taking now to protect your herd

Beef

Anthelmintic treatments can be administered to calves strategically during the first half of the grazing season to counter gut worm infections. The frequency of treatment depends on the persistency of the product used – speak to your vet or SQP about this
Giving an early season de-wormer ensures that few gut worm eggs are shed up to mid-summer, by which time any overwintered gut worm larvae present, will have died
Summer is a good time to use faecal egg counts (FECs) to monitor gut worm infection in first and second season grazing calves. Assess condition and weight and provided nutritional needs are being met, consider further investigation if calves are failing to thrive. If FECs come back positive, but below the 200 eggs/gram threshold for treating, test again in two to three weeks, as FECs can rise quickly in July and August
All-group treatments provide strong selection pressure for anthelmintic resistance. An alternative is to take an evidence-based approach and give anthelmintics on information obtained from growth monitoring and faecal egg count (FEC) analysis. Assess the risk with your vet
Graze youngstock on hay and silage aftermaths as they become available, as these fields will have a low parasite burden.
Where calves are grazing infected pasture and testing indicated a need for treatment, do not move them to new pasture immediately after. If they must be moved, leave 10% of the heaviest stock untreated
If concerned about de-wormer treatment failure, check faecal egg counts 14 days post benzimidazole (1-BZ) or ML (3-ML) treatment. Speak to the vet or SQP about this
Insecticide impregnated ear tags, tail bands, pour-on, spot-on and sprays containing pyrethroids can help reduce fly annoyance
Lungworm is not picked up using faecal egg counting, so it is vital to check calves regularly and to look out for signs of coughing. Contact the vet immediately if any coughing is heard
Early autumn is usually a high-risk period for liver fluke infection. Avoid grazing stock on wet areas that can harbor the intermediate host mud snail
Blood test any lambs on the farm (as sentinels) for liver fluke as they can inform the need for, or timing of cattle treatment

Dairy

Summer is a good time to use faecal egg counts (FECs) to monitor gut worm infection in first and second season grazing calves. Assess condition and weight gain and provided nutritional needs are being met, consider further investigation of calves are failing to thrive. If FECs come back positive, but below the 200 eggs/gram threshold for treating, test again in two to three weeks, as FECs can rise quickly in July and August
Anthelmintic treatments can be administered to calves strategically during the first half of the grazing season to counter gut worm infections. The frequency of treatment depends on the persistency of the product used – speak to your vet or SQP about this
Graze youngstock on hay and silage aftermaths as they become available, as these fields will have a low parasite burden
If concerned about de-wormer treatment failure, check faecal egg counts 14 days post benzimidazole (1-BZ) or macrocyclic lactone (3-ML) treatment. Speak to the vet or SQP about this
Insecticide impregnated ear tags, tail bands, pour-on, spot-on and sprays containing pyrethroids can help reduce fly annoyance
None of the flukicides have zero milk withhold and only a few products are licensed for use in milking animals. Some can be used in the dry period. Refer to VMD Guidance Note for products to use
Lungworm is not picked up using faecal egg counting, so it is vital to check calves regularly and to look out for signs of coughing. Contact the vet immediately if any coughing is heard
Early autumn is usually a high risk period for liver fluke infection. Avoid grazing stock on wet areas that can harbour the intermediate host mud snail
Blood test any lambs on the farm (as sentinels) for liver fluke, as they can inform the need for, or timing of cattle treatment

Resources

Vet, academic or researcher?

Take a look in Resources for more detailed information on all topics.

COWS Members

AgriSearch
AHDA
AHDB
AMTRA
APHA
Bishopton Veterinary Group
BCVA/Rob Howe
Farm First Veterinary Services
HCC
Anuschka Marsman
Moredun
NFU
NOAH
Mark Pass
QMS
RUMA
SRUC
The Livestock Partnership
Bruce Thompson
UK Agritech Centre
University of Liverpool
VMD