A leading livestock vet is urging farmers to mark and test any ewes that abort this year or to submit abortion material immediately for analysis to identify the cause and prevent further catastrophic losses.

John Hemingway from Shropshire Farm Vets warns that undiagnosed abortion outbreaks can devastate flocks, with enzootic abortion (EAE) and toxoplasmosis among the most common culprits.

“I’ve seen cases where losses exceed 40% due to EAE alone,” he says. “These diseases are persistent, highly infectious, and can cause significant financial damage if not addressed.”

According to the Animal and Plant Health Agency (APHA), EAE and toxoplasmosis ranked among the top 10 most frequent diagnoses last year¹. This is consistent with findings from the 2024 FlockCheck blood testing diagnostic scheme, subsidised by MSD Animal Health, which revealed that 80% of 382 sheep flocks had been exposed to toxoplasmosis and 26% to EAE². Additionally, 74 flocks (19.4%) tested positive for both pathogens².

APHA analysis has further highlighted toxoplasmosis and EAE as the two most common causes of sheep abortion³.

When to investigate abortion losses

Mr Hemingway advises farmers that while abortion levels up to 2% are within normal limits, anything above this should be investigated, alongside any suspiciously low scanning results.

“It may not always be possible to test for the cause of abortion at the time, but when this isn’t an option, mark any ewes that have aborted and arrange for blood testing after lambing,” he recommends.

GB sheep farmers can take advantage of MSD Animal Health’s 2025 FlockCheck scheme, which subsidises blood testing for six to eight aborted, unvaccinated ewes—or for barren ewes or those producing weak lambs.

• Testing for toxoplasmosis opened on 1st February 2025
• The EAE diagnostic phase starts on 1st April 2025
• The scheme closes at the end of June 2025

“This subsidised service provides farmers with valuable insights into potential causes of early lamb losses,” Mr Hemingway adds.

Risks of not investigating losses

Failing to identify the cause of abortion can lead to devastating consequences, particularly with EAE.

“With EAE, just one or two abortions in the first year can lead to an abortion storm in year two,” explains Mr Hemingway. “The more ewes exposed to aborted material, the higher the risk of widespread infection in the following lambing season.”

Vaccination as a preventative measure

Mr Hemingway says farmers should take a risk-based approach when deciding whether to vaccinate against EAE, but strongly recommends vaccination unless they operate a fully closed flock.

“If you’re buying in replacements and you don’t vaccinate them for EAE, one day it’s going to catch up with you,” he warns.

Data from MSD Animal Health’s 2024 flock health survey of 966 sheep units revealed that more than 30% of GB sheep flocks either don’t know their barren ewe rate or are reporting rates above 5% after lambing⁴.

MSD Animal Health veterinary adviser Dr Kat Baxter-Smith highlights that both EAE and toxoplasmosis reduce lambing percentages, increasing the workload and stress during lambing.

“Toxoplasmosis, caused by infection with the Toxoplasma gondii parasite, does not just cause abortion—it is also one of the leading infectious causes of early embryo loss in sheep⁵. It frequently results in barren ewes or weak, sickly lambs. Almost all flocks in Great Britain are likely to have been exposed to this parasite, meaning all breeding sheep should be considered at risk,” she explains.

“The cost of vaccination for both toxoplasmosis and EAE can easily be offset by reducing future barren rates and abortion losses,” Dr Baxter-Smith explains. “Ideally, every ewe should be vaccinated before she breeds, given the widespread disease threat and the significant financial impact of infection.”

Sheep farmers looking to take advantage of the 2025 Flock Check scheme should contact their local vet practice as soon as possible.

References

1. APHA Great Britain small ruminant quarterly report, disease surveillance and emerging threats Volume 28: Quarter 2 – April to June 2024

1. MSD Animal Health Flock Check Results 2024.
2. Veterinary Record (January 2020). APHA Surveillance Focus: investigating abortions in small ruminants
3. MSD Animal Health flock health survey 2024. Preparation for publication.
4. Moredun report Toxoplasmosis (Control of Toxoplasmosis abortion in sheep)