Low vaccine uptake leaves UK sheep flocks exposed to abortion risk

Sheep farmers could significantly reduce abortion losses by increasing vaccine uptake, as new data shows widespread exposure to key diseases across UK flocks.

Latest figures from AHDB highlight toxoplasmosis and enzootic abortion as ongoing threats to flock performance, with testing indicating far higher exposure than vaccination rates would suggest.

According to diagnostic results from 400 flocks tested last year through MSD Animal Health’s subsidised FlockCheck programme, 79% had been exposed to Toxoplasma gondii, while 35% showed exposure to Chlamydia abortus, the cause of enzootic abortion.

By contrast, AHDB data shows only around 26% of flocks were vaccinated against toxoplasmosis in 2024, compared with around 50% uptake for enzootic abortion vaccines.

The Animal and Plant Health Agency identifies the two diseases as the most common causes of sheep abortion in Great Britain, underlining the importance of preventative control ahead of lambing.

Farmers are being encouraged to investigate disease where abortion rates exceed 2% or scanning results fall below expectations, particularly when losses cannot be explained by management or nutrition.

The FlockCheck scheme, available through veterinary practices until 30 June 2026, offers subsidised blood testing to help identify underlying causes.

Testing can be carried out on aborted or unvaccinated ewes, as well as barren ewes or those producing weak lambs.

MSD veterinary advisor Dr Kat Baxter-Smith said early testing can support more informed flock health decisions.

“If results highlight an issue with either disease, both can be controlled effectively through a simple vaccination programme,” she said.

She warned that abortion diseases often remain undetected until losses escalate.

“Abortion diseases like enzootic abortion and toxoplasmosis often remain hidden until significant losses occur,” she said.

“Once established, they are extremely difficult and costly to manage, making prevention through vaccination vital.”

Enzootic abortion is highly contagious, with infected ewes often showing no visible signs until late pregnancy, when abortion or weak lambs may occur. Infected animals can remain carriers, posing an ongoing risk within the flock.

Toxoplasmosis can result in early embryo loss, barren ewes and weak lambs, with infection typically spread through pasture, feed or water contaminated by cat faeces. The parasite can survive in the environment for extended periods.

Dr Baxter-Smith said the level of exposure identified through testing highlights the need for vaccination to be considered well before tupping.

“Given the high exposure levels, vaccination should be a core part of flock health planning, especially for replacement ewes,” she said.

She added that both diseases are classed as NOAH Category 1. “Vaccines such as Enzovax® and Toxovax® should be regarded as standard practice on all sheep farms,” she said.

Farmers are being advised to speak to their vet about abortion testing, barren rates and pre-tupping vaccination plans to help protect flock health and maximise lambing performance.