Sheep farming

Controlling the spring rise

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, in fact, worms can reduce growth rate by up to 47% and wool production by up to 21%2.

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 lambs3.

FAI graph

Reducing the spring rise

A recent study4 has determined the impact of utilising persistent and non-persistent treatments to control the spring rise. The persistent treatment of CYDECTIN® Long Acting Injection for sheep, not only controlled the spring rise during the study, but led to lambs having strongyle egg counts below recommended treatment thresholds* for the entire study. The Control and non-persistent groups required lamb treatments, losing the potential to reduce lamb doses.



This lowered egg output and the ewes potentially “hoovering” the pasture led to both a lowered pasture contamination and numerically improved growth rate between weaning and shearing in the CYDECTIN LA group. In this 60 day period, the lambs in the CYDECTIN group outgrew the control lambs by 1.71kg and the non-persistent group by 0.99kg; this is likely due to the reduced pasture challenge4.



What about other farms?

Results from Parasite Watch farms across the country supported this, showing that farms 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. You can read more about our Parasite Watch scheme here.


CYDECTIN® contains moxidectin, a potent and persistent molecule that has been proven to help to control the spring rise4. 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. It’s important to control worms in the spring rise, to make sure your sheep stay healthy.

You can find out more on how to prepare for lambing success by clicking here.




  • Follow appropriate use guidelines
  • Use long acting moxidectin when it will be most beneficial for your farm
  • Decide whether it is best used for scab or worm control
  • Consider leaving fit/single bearing ewes untreated as these are likely to have a lowered spring rise
  • Consider utilising an exit Knock Out drench
  • Always watch out for Nematodirus battus outbreaks in the lambs

1. Nieuwhof, G.J. and Bishop, S. C. 2005. Animal Science, 81: 23-29
2. Charlier, J. et al 2014: Trends in Parasitology, Vol. 30, No. 7
3. GM Urquhart et al, 1998, Veterinary Parasitology.
4. Kerr et a 2017 A practical farm-based trial to compare ewe nematode control strategies in periparturient ewes, in press
5. Sargison N.D, et al., Vet.Parasitol (2012), doi: 10.1016/j.vetpar.2012.04.020
*Based on current recommendations, treatment thresholds vary according to farm situation and worm species

CYDECTIN 20mg/ml LA injection for sheep contains moxidectin POM-VPS. CYDECTIN 0.1% Oral Drench contains moxidectin POM-VPS For further information please see the product’s SPC or contact Zoetis UK Limited, Walton Oaks, Dorking Road, Tadworth, Surrey KT20 7NS. Technical Services and Customer Support 0845 3008034.
Use medicines responsibly ( Date of preparation January 2018 AH058/18