Liver Disease in Sheep: Fluke, Ragwort, and Nutritional Causes

Hepatic disease in sheep encompasses multiple causes from parasitic infection to plant toxicity, with welfare impact ranging from chronic production loss to acute fatal disease.

Key Facts

Liver fluke (Fasciola hepatica) causes both acute and chronic hepatic disease depending on burden and timing
Acute fluke disease from massive immature fluke migration causes sudden death in autumn and early winter
Ragwort (Senecio jacobaea) contains pyrrolizidine alkaloids causing chronic progressive hepatic cirrhosis
Facial eczema (sporidesmin toxin in New Zealand) destroys bile ducts causing photosensitization and hepatic failure
Body condition scoring correlates poorly with liver fluke burden - subclinical infection causes significant hidden welfare impact
Strategic flukicide treatment timing targets seasonal risk periods identified through local epidemiology
Liver fluke drug resistance to triclabendazole is increasing and requires monitoring

Welfare Considerations

Liver disease in sheep ranges from chronic subclinical welfare impact - reduced growth, impaired reproduction, lowered resilience - to acute fatal disease. Liver fluke burden causes suffering that is largely invisible to casual observation; affected sheep may appear reasonably healthy while experiencing significant physiological dysfunction. Ragwort toxicity causes chronic suffering through progressive liver failure with jaundice, weight loss, and neurological signs. Control programs - strategic flukicide use, pasture management, and ragwort eradication - prevent substantial welfare burden across large sheep populations.

What You Can Do

Implement a strategic flukicide program timed to local epidemiology and liver fluke risk periods
Use fluke egg counting and liver condemnation data to assess flock burden
Test flukicide efficacy periodically - triclabendazole resistance is spreading
Eradicate ragwort from sheep pastures as a legal requirement in many countries
Avoid overgrazing that increases fluke habitat and forces sheep to graze contaminated areas
Monitor liver fluke resistance development by testing flukicide efficacy on your operation
Discuss local risk periods and optimal treatment timing with your vet