MSD Veterinary Advisor Dr Kat Baxter-Smith
AHDB Data Highlights Opportunity To Strengthen Abortion Control In UK Flocks
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Latest AHDB¹ data highlights a significant opportunity for UK sheep farmers to further strengthen flock health by increasing uptake of vaccines that protect against abortion caused by toxoplasmosis and enzootic abortion. The Animal and Plant Health Agency² (APHA) identifies these two diseases as the most common causes of sheep abortion in Great Britain, underlining the value of effective preventative strategies ahead of lambing.
While availability issues have previously affected supplies of some abortion vaccines in the past, uptake had already reached around 50%¹ for enzootic vaccines according to AHDB data, demonstrating growing awareness of the benefits of vaccination. Vaccination for toxoplasmosis is lower with only 26% of flocks vaccinated in 2024¹, highlighting considerable opportunity for greater protection in the national flock.
Diagnostic results from 400 flocks tested through MSD Animal Health’s subsidised FlockCheck programme³ last year found that 79% had been exposed to Toxoplasma gondii and 35% to Chlamydia abortus, the bacterium responsible for enzootic abortion. These results provide farmers with valuable insight to make targeted vaccination decisions, helping safeguard flocks and maximise lambing outcomes.
Farmers are being reminded that where abortion rates exceed 2%, or scanning results are lower than expected, the subsidised FlockCheck scheme, available through veterinary practices until 30 June 2026, offers practical support. The scheme provides blood testing for six to eight aborted or unvaccinated ewes, or for barren ewes or those producing weak lambs, helping identify underlying causes and inform the value of a pre-tupping vaccination programme.
“If results highlight an issue with either disease, both can be controlled effectively through a simple vaccination programme,” said MSD Veterinary Advisor Dr Kat Baxter-Smith.
“Abortion diseases like enzootic abortion and toxoplasmosis often remain hidden until significant losses occur. Once established, they are extremely difficult and costly to manage, making prevention through vaccination vital.”
Clinical signs of disease
Enzootic abortion is highly contagious, with infected ewes often showing no signs until late pregnancy, leading to abortion or weak lambs. Infected ewes can become lifetime carriers, posing ongoing risk. Toxoplasmosis also causes early embryo loss, barren ewes, and weak lambs. Infection occurs primarily through pasture, feed, or water contaminated by cat faeces, with parasite eggs surviving over a year, making vaccination the most reliable protection.
“Given the high exposure levels, vaccination should be a core part of flock health planning, especially for replacement ewes,” added Dr Baxter-Smith. “Both toxoplasmosis and enzootic abortion are classified as NOAH Category 1 diseases, so vaccines such as Enzovax® and Toxovax® should be regarded as standard practice on all sheep farms.”
Farmers are encouraged to discuss testing for abortion and low barren rates, as well as vaccination plans, with their vet to help safeguard their flock.
References
- 2025 AHDB Vaccine Uptake Report for Cattle and Sheep Vaccine uptake report for cattle and sheep | AHDB
- Veterinary Record (January 2020). APHA Surveillance Focus: investigating abortions in small ruminants
- MSD 2025 FlockCheck results from 400 farms. Data on file
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