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Enzootic Abortion in Sheep: Chlamydiosis Welfare

Enzootic abortion of ewes (EAE) is the most common cause of infectious abortion in UK sheep. This guide covers welfare impacts and prevention.

Key Facts

EAE is caused by Chlamydia abortus bacteria acquired at lambing from infected material
Ewes typically abort in the last 2-3 weeks of pregnancy or produce weak lambs
The bacterium establishes latency and reactivates in subsequent pregnancies
Abortion storms cause significant welfare distress and economic losses
Vaccination before breeding provides excellent protection
EAE is a significant zoonosis causing severe illness in pregnant women

Welfare Considerations and Management

Welfare-centred EAE management requires vaccination as the primary prevention tool. The Enzovax vaccine provides strong protection when administered before exposure (pre-breeding). Biosecurity at lambing reduces spread — separating aborting ewes and careful handling of abortion material prevents spread to other ewes and to humans. Oxytetracycline treatment during the last 4 weeks of pregnancy reduces abortion losses in infected flocks. Pregnant women must not be exposed to lambing.

What You Can Do

Vaccinate ewes against EAE before every breeding season if in an endemic area
Isolate aborting ewes and handle abortion material hygienically to prevent spread
Warn all pregnant women — EAE causes severe illness and pregnancy complications in humans
Test abortion material to confirm EAE rather than assuming the diagnosis