Cattle Worm Control Welfare: Responsible Anthelmintic Use

Internal parasites cause significant welfare impacts in young cattle. Responsible anthelmintic use balances individual welfare with the growing threat of drug resistance.

Key Facts

Ostertagia ostertagi, the brown stomach worm, is the most welfare-significant parasite of cattle in the UK
Type II ostertagiosis occurs when arrested larvae re-emerge in spring, causing sudden severe disease in yearlings
Macrocyclic lactone resistance in cattle nematodes is emerging in Europe, limiting treatment options
Targeted selective treatment using FAMACHA-equivalent body condition scoring reduces resistance selection pressure

Welfare Considerations

Parasitic gastroenteritis causes weight loss, diarrhoea, hypoproteinaemia (bottle jaw), and in severe cases death. Welfare-positive worm control uses strategic treatment at high-risk periods (housing in autumn, turnout in spring) rather than calendar-based blanket dosing. Refugia maintenance — leaving a proportion of animals untreated — preserves susceptible parasite populations and slows resistance development. Annual egg count monitoring and anthelmintic efficacy testing (reduction egg count testing) guides strategic use.

What You Can Do

Implement a parasite control plan with your vet based on annual faecal egg count monitoring
Conduct anthelmintic efficacy testing every 3 years to detect emerging resistance early
Maintain refugia by leaving low-risk animals untreated during strategic treatments
Support research into vaccine development against Ostertagia as an alternative to anthelmintic dependency