Comprehensive welfare management of liver fluke in sheep — from acute disease to strategic control.
Liver fluke causes a spectrum of welfare impacts that varies dramatically by infection burden and timing. Acute fasciolosis — massive simultaneous larval migration through the liver parenchyma — causes acute haemorrhagic hepatitis and sudden death. Affected sheep may be found dead without premonitory signs. Those showing clinical signs display severe abdominal pain, rapid breathing, and rapid deterioration.
Subacute fasciolosis, caused by moderate larval burdens, causes significant welfare impairment over weeks. Sheep lose body condition rapidly, become anaemic, and are unable to maintain production or reproductive function. The progression from apparently adequate body condition to severe debility can be rapid during peak fluke challenge periods.
Chronic fasciolosis from adult fluke in bile ducts causes protein loss, anaemia, and bottle jaw. Affected sheep are chronically debilitated — unable to maintain normal growth, reproduction, or immune function. The insidious nature of chronic disease means individual sheep may suffer significantly before the flock-level impact is recognised.