The UK sheep industry faces an escalating worm challenge this autumn, with Haemonchus posing a significant threat to both lambs and adult sheep. Contrary to its traditional association with southern regions, the parasite has become widespread, impacting flocks across the country.
As detailed by post-mortem vet, Ben Strugnell, it is crucial to remember that adult sheep do not develop immunity to Haemonchus, making them equally susceptible to its detrimental effects (Cupriak, 2024). Furthermore, the prevalence of different worm species varies throughout the year, meaning wormers are effective in the spring may not adequately control worm species that are active in the autumn.
Veterinarians should guide farmers towards a proactive worm control strategy, incorporating regular faecal egg counts (FECs) to monitor worm burdens and inform treatment decisions. Weaned lambs, in particular, require close attention, as rapid growth rates can mask the insidious impact of worm infestations. To assess wormer efficacy, drench checks are recommended. This involves conducting a follow-up FEC test 7–14 days after treatment to identify potential resistance issues and adjust treatment protocols accordingly. Strategic management of ‘tail-end’ lambs is also crucial. Housing these lambs, selling them or moving them to alternative grazing can help minimise pasture contamination and reduce worm burdens in the following spring.
Strugnell recommends considering an annual break dose of a Group 4 wormer to effectively remove accumulated worm burdens and slow the development of resistance to older wormer groups.
The long-term sustainability of sheep farming relies on integrated parasite management that minimises reliance on anthelmintics. By promoting proactive monitoring, responsible anthelmintic use and alternative control measures such as grazing management, we can contribute to a healthier environment and more resilient sheep production systems. This autumn, by working collaboratively with farmers, veterinarians can safeguard sheep health, optimise productivity and ensure the long-term sustainability of the UK sheep industry.