Bluetongue virus serotype-3 (BTV-3) has become one of the most important emerging disease threats facing cattle and sheep farmers in Ireland. After spreading across mainland Europe and the UK in 2023–2025, the first evidence of BTV-3 infection in Irish cattle was detected in January 2026.
For dairy and suckler farmers, understanding the disease, its potential economic impact, and the role of vaccination is now essential for protecting herd health and farm profitability.
What is Bluetongue Virus?
Bluetongue is a viral disease of ruminants caused by the bluetongue virus (BTV). It affects cattle, sheep, goats and deer but does not pose a risk to humans or food safety.
The virus is spread primarily by biting midges (Culicoides species) rather than through direct contact between animals, but it can also spread by close contact between animals, through nasal/oral secretions, venereal spread in semen (stock bulls) and iatrogenically with needles when vaccinating or injecting multiple animals.
Ireland’s climate supports the presence of these midges, particularly during the vector-active season from late spring through autumn, which means the risk of virus transmission increases during warmer months. Schmallenberg virus, also spread by midges, emerged in Ireland in 2012 and has since become endemic in the cattle and sheep population.
Why BTV-3 Matters for Irish Farmers
BTV-3 first emerged in the Netherlands in 2023 and spread rapidly through several European countries in 2024 and 2025 before reaching the UK and the island of Ireland.
Because Ireland had previously been free from the disease, the arrival of BTV-3 has several implications:
- Increased animal health risks
- Potential movement and trade restrictions, ranging from none to PCR tests, vaccination and quarantine
- Additional management and veterinary costs
- Greater uncertainty around herd fertility and performance
Clinical Signs of Bluetongue in Cattle
Cattle are often less severely affected than sheep, but they can still show significant production and fertility losses.
Common clinical signs in cattle include:
- Fever and lethargy
- Reduced milk yield in dairy cows
- Swelling of the face, lips, or tongue
- Mouth lesions and excessive salivation
- Lameness due to inflammation around the coronary band
- Reproductive problems such as early embryonic death, abortions or malformed calves
In some outbreaks in the UK, cases were first detected following abortions or calves born with neurological abnormalities, highlighting the reproductive risks of infection.
Economic Impact: Lessons from Europe and the UK
While the full impact of BTV-3 in Ireland is still developing, the experiences of farmers in mainland Europe and the UK provide important warnings.
Across northern Europe, BTV-3 outbreaks during 2023–2025 resulted in:
Production losses
- Reduced milk yield in dairy herds
- Lower growth rates in beef cattle
- Fertility problems and abortions – in France, an estimated 202500 less calves were born between June 2024 and June 2025
Animal health costs
- Increased mortality
- Increased veterinary treatments
- Additional labour and management
Trade and movement impacts
- Testing requirements
- Movement restrictions during outbreaks
Previous bluetongue epidemics in Europe have demonstrated the scale of economic damage that vector-borne diseases can cause. For example, earlier bluetongue outbreaks in Germany generated tens of millions of euros in direct and indirect costs to the livestock sector.
For Irish farms, the biggest economic risks include:
- Milk production losses
- Reduced calving rates
- Restricted animal movements
- Increased disease management costs
Bluetongue Vaccination in Ireland
Vaccination is emerging as the most important tool available to farmers to reduce the risk of BTV-3 impacts.
Since 1 January 2026, vaccination against BTV-3 has been permitted for cattle and sheep in Ireland.
It is recommended that farmers strongly consider vaccinating animals in spring, ahead of the summer and autumn period when midge activity – and virus transmission – is highest.
Benefits of vaccination
Vaccination can:
- Reduce clinical disease
- Lower virus circulation within herds
- Protect fertility and productivity
- Reduce the overall impact of outbreaks on farms
Farmers interested in vaccination should discuss the option with their private veterinary practitioner (PVP) and arrange vaccination through their vet where appropriate.
What to Expect for the 2026 Grazing Season
Because BTV-3 is now present on the island of Ireland, the 2026 vector season will be an important test for the Irish livestock sector.
The risk of spread will depend on several factors:
- Weather conditions affecting midge populations
- Overwintering of the virus in the midge population
- Further incursion of the virus from the South West of England
- Vaccination uptake across herds
- Early detection and surveillance
- Farm-level disease management
Preparation during the spring period — particularly vaccination and herd health planning — will be critical in limiting the impact of bluetongue on Irish dairy and beef farms.
The AHDB in the UK have created a helpful cost calculator, which as a herdowner can help you make a decision on the economic benefit or otherwise on Bluetongue vaccination in 2026.
Key Take-Home Messages for Farmers
- Bluetongue virus serotype-3 has now been detected in Ireland.
- The disease is spread by biting midges and poses no risk to human health.
- Dairy and suckler herds may experience milk loss, fertility problems, and economic impacts.
- Vaccination is permitted in Ireland from 2026 and should be discussed with your vet.
- Preparing now can significantly reduce the impact on your herd.