The latest programme results published by Animal Health Ireland (AHI) on the Bovine Viral Diarrhoea (BVD) National Eradication Programme paint a concerning picture of an increased incidence of disease in 2025. The number of BVD positive calves identified up to week 23 of 2025 was recorded at 466 head.

This represents an increase of 160 calves, or 52% rise, when compared to the corresponding period in 2024. The figures are still far lower than the incidence rates in previous years, as outlined in Table 1, but are a concern for the programme and moving to the next step of securing BVD-free status and being able to move away from tissue tag testing.

The jump in incidence rates appears to be stemming from a number of significant outbreaks at herd level with the herd incidence rate of 152 herds increasing by 19 herds or 14.3%.

AHI analysis up to the end of April showed at the time seven herds recording more than 12 positive calves, with two herds recording at that stage between nine and 12 positive calves and four herds between six and eight positive cases. These figures have obviously increased since that time period.

The number of calves tested to date in 2025 stands at just over 1.8m head. The total number tested in 2024 was over 2.3m and, while hopes of a significant reduction in incidence are fading, it is still hoped that the incidence rate will be diluted by fewer cases in the second half of the years.

Underlying cause

Earlier this year, AHI reported that it was carrying out analysis to assess the reasons behind the increase adding that they were in constant contact with the Department of Agriculture on the issue.

They urged farmers to be vigilant, sample and test calves promptly and to keep untested animals separate from pregnant animals and act quickly if a positive result is obtained. This advice remains in place.

The incidence rate is disappointing in light of cases reducing by 35% in 2024.

Conditions for freedom under the Animal Health Law (AHL) include not having had a confirmed case in the previous 18 months and having BVD-free status for 99.8% for all herds representing at least 99.9% of cattle.

However, an application on BVD-free status does not come down solely to achieving these figures.

If Ireland applies for BVD-free status, then a condition under the AHL bans all vaccination as given the increase in incidence this year it leaves herds open to further outbreaks.