How to Tackle Haemonchus – Dawn Bowness and Kaz Strycharczyk | VETchat by The Webinar Vet

·32 min·3 clips

Two sheep health experts explain why Haemonchus, a blood-sucking worm, is becoming a new threat in northern England.

Host Anthony Chadwick introduces the episode, focusing on Haemonchus control in partnership with Elanco. Dawn Bowness, a sheep health advanced practitioner from Clevedale Vets, and Kaz Strycharczyk, a farm vet from Black Sheep Farm Health, share their expertise. They begin by noting Haemonchus was historically less problematic but has spread over decades, with prevalence poorly understood due to diagnostic limitations. The worm resembles other Trichostrongyles on standard fecal egg counts, often requiring special staining or post-mortem for identification. Climate change is creating warmer, wetter conditions that favor Haemonchus replication, extending its season from spring to late autumn. Kaz describes clinical signs, ranging from acute sudden death with no scouring to chronic ill thrift, emphasizing anemia visible as white eye disease. Dawn explains that outbreaks depend on favorable conditions overlapping with worm presence, not just the worm itself. The discussion covers immunity, noting adult ewes may not develop robust immunity due to sporadic exposure, necessitating their inclusion in monitoring programs. Treatment approaches are debated: acute outbreaks may require heavy-handed use of broad-spectrum anthelmintics or clazantel, but post-drench checks are crucial to verify efficacy. Dawn stresses the importance of maintaining refugia (susceptible worm populations) to prevent resistance, warning against practices like dosing and moving to clean ground. They recommend targeted selective treatments using criteria like body condition score or FAMACHA conjunctival color scoring in non-emergency situations. The episode concludes with a reminder that any anthelmintic class could be effective against Haemonchus in the UK, but farm-specific history and resistance monitoring are essential.

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