Don’t let winter worms wiggle in

By Contributed

Jun 30, 2026

Worms and scours can be a significant problem in weaners and lambing ewes with the limited feed and cold stress of winter.

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Winter conditions provide ideal conditions for the survival of worm larvae on pastures, and feed may also be short.

Sheep that are nutritionally stressed and in light condition grazing short pastures are likely to be affected by worms and scouring.

Worms should be considered in all ill-thrifty or scouring sheep, regardless of when the sheep were last drenched.

To help establish whether worms are the cause, you should consider the following:

the sheep’s nutrition, including the feed availability, supplemental feeding and stocking rate
the sheep’s class and condition, including their body condition score
the drench program, including the product/s used and date/s drenched, particularly the time since the last treatment.

To know for sure, faecal samples from at least five affected and five non-affected sheep should be submitted for worm egg counts.

To help manage worms in sheep during winter:

provide adequate feed for weaners and lambing ewes on low worm pastures such as those prepared by smart grazing over summer, those previously grazed by cattle, or those used for cropping
weaners and lambing ewes need to be in a condition score of around 2.5. If lighter, they will need preferential treatment and feeding
check worm egg counts by Wormtest (samples from 10 representative sheep) every four to six weeks through winter
confirm that the drench worked by Wormtest at the time of drenching and 10 to 14 days later.
check worm egg counts in lambing ewes about four weeks before lambing.

For further information, contact your local veterinarian or Agriculture Victoria Animal Health Officer or use WormBoss.

Visit the Drought support page or call 136 186 for information about available support.

– Dr Jeff Cave, Senior Veterinary Officer