Sheep vaccines could save farmers up to £8,430 per 100 ewes, study finds

Sheep farmers could save up to £8,430 per 100 ewes by vaccinating against abortion diseases, with new research showing the financial benefits consistently outweigh the costs.

The study, led by veterinary surgeon Dr Laura Worsley, analysed more than 10,000 flock scenarios to assess the impact of vaccination against enzootic abortion of ewes (EAE) and toxoplasmosis.

Across every scenario modelled, vaccination delivered a positive return — including in flocks already affected by disease and those yet to be exposed.

In endemic flocks, the average annual increase in net revenue reached £1,932 for EAE and £2,514 for toxoplasmosis in a 100-ewe flock.

However, the biggest gains were seen in previously unexposed flocks, where vaccination acts as insurance against a potential abortion outbreak. In these cases, savings of £5,640 for EAE and up to £8,430 for toxoplasmosis were identified.

Despite the clear financial case, uptake remains relatively low across the industry.

Dr Worsley said upfront costs and timing often deter farmers from vaccinating.

“The headline cost can put farmers off,” she said, but added that “across more than 10,000 modelled outcomes, vaccination never resulted in a financial loss”.

She also pointed to the challenge of decision-making ahead of the risk period.

“Farmers are making that decision at the point furthest away from seeing the consequences,” she said, noting that “regardless of lamb sale price, vaccination remains financially beneficial”.

The modelling showed lamb price had the greatest influence on returns, meaning higher-value flocks stand to benefit most.

Other factors — including abortion rates, neonatal mortality and barren ewe levels — also played a significant role, with farms experiencing greater losses seeing the strongest improvements.

Dr Worsley warned that the true cost of abortion disease is often underestimated.

“It’s not just the abortion that needs costing in,” she said, highlighting additional impacts such as barren ewes, replacement costs, weaker lambs and increased labour.

“When you look at the full picture, the economic impact is much greater than many farmers realise.”

Industry data underlines the scale of the risk. The Animal and Plant Health Agency identifies enzootic abortion and toxoplasmosis as the most common causes of sheep abortion in Great Britain.

Yet vaccination rates remain relatively low, with around half of flocks protecting against enzootic abortion and just 26% vaccinating for toxoplasmosis.

Further insight from the FlockCheck programme highlights widespread exposure, with 79% of flocks testing positive for Toxoplasma gondii and 35% for Chlamydia abortus.

MSD veterinary adviser Dr Kat Baxter-Smith warned that the diseases often go unnoticed until significant losses occur.

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

She added that “given the high exposure levels across GB flocks, vaccination should form a core part of flock health planning”.

Enzootic abortion is highly contagious and often shows no signs until late pregnancy, while toxoplasmosis can lead to early embryo loss, barren ewes and weak lambs, typically spread through contaminated pasture, feed or water.

With margins under pressure and exposure levels high, the findings suggest improving vaccination uptake could offer one of the most straightforward ways to protect flock productivity and profitability.

Farmers are being encouraged to speak to their vet about testing and vaccination strategies, including the subsidised FlockCheck scheme available until 30 June 2026.