Vets from global veterinary health company Ceva Animal Health are urging farmers to vaccinate their sheep flocks with Cevac Chlamydia early in the season to help protect their ewes from enzootic abortion of ewes (EAE).

The company wants farmers to be aware that vaccinating their flocks early in the season will also help avoid Cevac Chlamydia vaccine supply issues later in the year.

Ruminant veterinary advisor at Ceva Animal Health, Harry Walby, said EAE remains one of the most commonly diagnosed causes of abortion in UK sheep and costs the UK sheep industry up to £20 million annually.

Walby also said that the company has been warned that there could be shortages of the vaccine later in the year.

“We have been advised that there will be stock availability issues later in the year and so we are encouraging farmers to vaccinate their flocks as early as possible to utilise current provisions of Cevac Chlamydia and help ensure the continuous supply of the vaccine,” he said.

Recognised specialist in sheep health and production at the Royal College of Veterinary Surgeons (RCVS), Fiona Lovatt, said that EAE outbreaks are devastating, which is why farmers should be prepared and vaccinate early.

“An outbreak of enzootic abortion is devastating – this is a disease for which it is essential to ‘Plan ahead, Prevent disease and Protect the flock’,” she said.

“Once we get close to tupping, there is very little we can do if there is a shortfall in vaccine supply at the crucial time.

“It would be sensible to be ahead of the game and ensure that first-time lambers – whether ewe lambs or shearlings – are vaccinated earlier in the season and while there are stocks available.”


Ceva Animal Health said EAE is caused by the bacterium chlamydophila abortus, which is spread from sheep to sheep, predominantly at lambing time.

Infection in a flock can result in the birth of dead and/or weak lambs from about three weeks before lambing is due to start, the company said.

If sheep are infected after about 100 days of pregnancy, they will not abort at this lambing, but the bacteria will become latent and then reactivate causing abortion at the subsequent lambing.

“The highly infectious nature of chlamydia, as well as this latent infection means that levels of abortion can be relatively low one year, before resulting in a storm and significant losses in the next year,” Ceva Animal Health said.

“Some ewes may not abort but can still shed the bacterium, meaning neonatal ewe lambs could be infected. In a previously uninfected flock the infection is generally bought in.”