Anthelmintic resistance in cattle and sheep

Liver fluke can cause disease in both sheep and cattle but the consequences are much more serious for sheep

Not treating the parasites results in severe disease. File Picture. 

In general, sheep of all ages, not just lambs, are often treated with anthelmintics regularly and so the selection pressure for resistance is quite high each year.

In addition, the consequences of treatment failure due to anthelmintic resistance can be severe; in regions where the blood-sucking stomach worm, Haemonchus contortus, predominates, deaths through anaemia can be seen in both ewes and lambs.