Sheep abortion rates at highest level since 2020
“Now is the time to review 2026 lambing performance and abortion losses" - Kat Baxter-Smith, MSD Animal Health.
New data from the Wales Veterinary Science Centre (WVSC) has shown diagnostic sheep abortion rates to be at their highest levels since 2020, after abortion submissions increased this year.
The enzootic abortion of ewes (EAE), which is caused by Chlamydia abortus, was found to be the most common cause of ovine abortion. This accounted for 72 per cent of submissions between January and June 2026.
Meanwhile, interim results from MSD Animal Health’s 2026 FlockCheck diagnostic scheme showed high exposure levels to common causes of ovine abortion.
Out of 421 samples, 75 per cent tested positive for toxoplasmosis. Similarly, nearly 30 per cent of 212 samples returned a positive result for EAE.
MSD Animal Health is now urging farmers to take a risk-based approach to vaccination. It says this is particularly important where replacements are introduced and where flocks have experienced higher barren rates of lamb losses.
Dr Kat Baxter-Smith, MSD veterinary adviser, said that non-pregnant ewes can be vaccinated at least four weeks before tupping, but suggested summer was the ideal window for action.
She said: “These are preventable diseases that can cause devastating losses, yet many farmers don’t realise there’s a problem because losses often go unrecorded or unexplained.”
“Unless barren and abortion rates are below 2%, or the flock is fully closed, ewe vaccination should be considered. Both are NOAH Category 1 diseases3, meaning vaccination should be standard practice.”
Toxoplasmosis, caused by Toxoplasma gondii, is also a driver of barren ewes and weak lambs. The infection is caused by ingestion of oocysts in cat faeces, with parasite eggs surviving for over a year.
Dr Baxter-Smith said: “The data clearly highlight persistent levels of disease exposure, with enzootic abortion and toxoplasmosis remaining entrenched in UK sheep flocks despite both being fully preventable through vaccination. These are not isolated issues, and the evidence shows they continue to contribute to significant reproductive losses across flocks.
“Now is the time to review 2026 lambing performance and abortion losses, and work with your vet to put prevention strategies in place ahead of the 2027 breeding season.”
Image © MSD Animal Health
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