Gastrointestinal parasites are among the most significant welfare burdens for sheep globally, with anthelmintic resistance making effective control increasingly challenging.
Sheep parasite welfare involves both acute suffering from heavy burdens and chronic welfare compromise from persistent moderate infection. Haemonchosis causes anaemia, weakness, and death that can occur within days of heavy challenge. More commonly, chronic moderate infections cause reduced growth, weight loss, diarrhoea, and vulnerability to other health problems - a welfare backdrop affecting productivity and daily experience. The anthelmintic resistance crisis threatens to undermine effective treatment and requires strategic management rather than blanket dosing. Targeted selective treatment - treating only animals with clinical need identified through faecal egg counting - reduces treatment frequency while improving resistance management.