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Sheep and lambs

Realise your lambs’ growth potential now, and help remove worm resistance.


Sheep wormers are a vital part of any gastrointestinal worm control programme. There has been a lot of talk about resistance to anthelmintics recently, but resistance doesn’t always mean the product will completely fail, rather, there will be a reduction in the percentage of worms killed.

This affects productivity although the effects can be hard to see unless you are monitoring growth rates or other production measures. Even low levels of resistance can leave enough worms to affect growth rates. When the number of resistant worms is more than 10%, we start to gradually lose lamb performance1. This is why we need to put a sustainable worm control programme in place.

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Mid-late season clear-out dose in lambs.

  • Zolvix clears out resistant worms that, having survived earlier treatments, may be limiting lamb performance.
  • Helps to improve health, live weight gain and productivity2.
  • Reduces contamination of the pasture with resistant eggs3.

Farm protection (quarantine) dose.

  • All sheep arriving onto a farm, however healthy looking, can bring resistant worms.
  • Dose all incoming sheep with Zolvix as part of a quarantine programme to help protect your farm from resistant worms.

Resistance management.

  • Incorporating Zolvix into worm control strategies, when resistance levels are low, can help slow the speed of resistance and preserve the older classes of wormers2.


Avoid under dosing: it allows more worms (resistant and partially resistant) to survive. Under dosing can occur because the weight of the sheep is underestimated, the applicator is not calibrated correctly or the dose is not administered correctly.

Avoid over use: every time a wormer is used, that class of wormer is being selected for resistance. Reducing the unnecessary use of anthelmintics is important, as well as ensuring the right product is being used every time. Routine faecal egg counts are one method to help determine the need for wormers. Knowing your resistance status will help choose the right products for your farm.

Avoid worming in times of low refugia: for example, try and avoid dosing and moving to clean pasture, by either leaving 10% of the animals untreated or delay the move for a few days after treatment.

Always adopt a farm protection quarantine treatment: new or returning stock should always be subject to a farm protection quarantine treatment, ensuring resistant worms or other parasites are not inadvertently brought on farm. Always yard or house stock for 24-48 hours before turning out on to dirty pasture.

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  1. The production costs of anthelmintic resistance in sheep managed within a monthly preventive drench program I.A. Sutherland, J. Shaw, R.J. Shaw Veterinary Parasitology 171 (2010) 300–304.
  2. Managing anthelmintic resistance: Modelling strategic use of a new anthelmintic class to slow the development of resistance to existing classes DM Leathwick and BC Hosking, New Zealand Veterinary Journal 57(4), 203-207, 2009
  3. www.scops.org.uk.

ZOLVIX™ 25 mg/ml oral solution for sheep. Active ingredient monepantel. Legal category POM-VPS in the UK. Information regarding the side effects, precautions, warnings and contra-indications can be found in product packaging and leaflet; further information can be found in the Summary of Product characteristics or by contacting Elanco Animal Health on +44(0)1256 353131. Or write to Elanco Animal Health, Lilly House, Priestley Road, Basingstoke, Hampshire RG24 9NL.Use medicines responsibly www.noah.co.uk/responsible. Advice on the use of this or alternative medicine must be sought from the medicine provider. Elanco, Zolvix and the Diagonal Bar are registered trademarks owned by Elanco or its affiliates. ©2019 Elanco or its affiliates. PM-UK-19-0112

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