Sheep farming

Controlling worms in sheep: The Spring Rise

The following material is intended for UK professional keepers of animals, UK veterinary surgeons and SQPs only. By continuing to browse this site, you confirm that this describes you

Parasitic gastroenteritis is the primary production limiting disease of sheep in the UK.  The annual cost of stomach worms to the British sheep industry is estimated to be £84 million1.This is because stomach worm infections decrease growth rates in lambs. As the level of challenge increases, the growth rate will decrease.

What is the Spring Rise?

The Spring Rise is a relaxation of immunity in the ewe around the period of lambing. This results from changes in the immune status of the ewe leading to increased egg production by female roundworms and the maturation of arrested larvae. The risk period is from around 2 weeks before lambing until around 6 weeks post lambing. This period of increased egg shedding leads to pasture contamination and is a risk to the lambs2.

The levels of parasites in the lambs have been shown to affect their growth rate3. This means it will take longer to get to target weight meaning a negative effect on their productivity.


A recent UK study has shown that single bearing ewes produce less eggs and therefore less pasture contamination than twin bearing ewes, which produce less than triplet bearing ewes. This study also showed a higher weight gain in the single group than the twins and in turn the triplet group4.

Reducing the Spring Rise

Reducing the Spring Rise from the ewes will therefore lower the pasture contamination and helps protect lambs from worms.  CYDECTIN® contains moxidectin, a potent and persistent molecule that has been proven to help to control the spring rise.

CYDECTIN® Long Acting Injection for sheep has a persistency period of up to 111 days meaning that treatment of the ewe around lambing time can reduce the egg output of those ewes and help to control pasture contamination and the egg output of the lambs5

Results from Parasite Watch 2016, supported this showing that farms across the UK that chose to use CYDECTIN LA for Sheep to help to suppress the Spring Rise saw reduced need to worm their lambs throughout the season due to reduced burdens, compared with farms that did not.


Parasite Watch and CYDECTIN are part of the Parassist range of products, tools and services designed to support your decision making and improve your productivity. Parassist is a completely novel approach to parasite control and we believe that parasite control is about more than just products.   We’ve also put together a dedicated team of highly respected vets working in the field of herd and flock health. They will partner with you to help you find innovative solutions to complex challenges and new protocols that are fit for purpose, customised to the season and your area.

Partner with Parassist for an altogether more professional approach to parasite control; visit the Parassist website for further information

1.Nieuwhof, G.J. and Bishop, S. C. 2005. Animal Science, 81: 23-29
2.GM Urquhart et al, 1998, Veterinary Parasitology.
3.Coop et al 1982 J Agric Sci 98, 247-255
4. Kerr, C et al A monitoring study to explore gastrointestinal helminth burdens of ewes of different fecundities in the periparturient period and effects on lamb growth rates 2016
5. Sargison N.D, et al., Vet.Parasitol (2012), doi: 10.1016/j.vetpar.2012.04.020


CYDECTIN 20mg/ml LA injection for sheep contains moxidectin POM-VPS . CYDECTIN 0.1% Oral Drench contains moxidectin POM-VPS  For further information see the SPC or contact Zoetis UK Ltd, Walton Oaks, Dorking Road, Walton on the Hill, Tadworth, Surrey, KT20 7NS. Technical Services and Customer Support 0845 3008034. Use medicines responsibly