IT’S likely that an insidious infectious disease was a significant cause of barrenness or abortion in ewes last year, according to the latest diagnostic results from MSD Animal Health.
Blood samples from UK sheep farms were tested during 2016 when the subsidised Expertis FlockCheck diagnostic service was available to vets between March and July, last year. 
According to the data, 79% of flocks tested showed evidence of exposure to the parasite toxoplasma gondii, which causes toxoplasmosis. 
The data also revealed that 76% of flocks had been exposed to chlamydophila abortus bacteria, the organism causing enzootic abortion (EAE), with 60% of flocks having been exposed to both organisms.
“A preliminary analysis of 2017 data to date shows a similar overall disease picture, albeit with a slightly higher figure of 81% for exposure to toxoplasma gondii,” said MSD Animal Health’s livestock veterinary adviser, Stephanie Small.
Ms Small said this highlighted the widespread prevalence of these financially damaging diseases in the national flock and is urging all sheep producers to discuss their individual farm situation with their vet, well in advance of the upcoming autumn tupping season.
She added: “Toxoplasmosis, in particular, remains a key cause of barrenness and abortion in UK sheep flocks. It also causes re-absorptions, mummified foetuses, stillbirths and weakly lambs, and as a result of the range of different disease pictures that can manifest, its effects on flock profits are often vastly underestimated. 
Toxo is so widespread that the industry focus should be on preventing infection in breeding ewes and the best way to do that is to vaccinate replacements well before they go to the ram. The clear industry advice is to ensure every ewe is vaccinated before it breeds.
“Sheep pick up the infection from the environment and so normal biosecurity measures are not enough to control the disease. Infected cats shed toxoplasma eggs in their faeces and sheep become infected when they ingest these eggs from contaminated pasture, feed and water,” Ms Small added. 
On EAE, she said: “This is caused by chlamydophila abortus bacteria and the disease can cause devastating abortion storms affecting approximately 25% of ewes. Once a flock has it, it is likely it will never disappear due to its persistence in carrier sheep. It often arrives via bought-in replacements and is passed on from ewe to ewe at lambing time. If an unvaccinated ewe is infected she will more than likely abort in the next pregnancy.”
Ms Small urged those who had a flock barren rate greater than 2% last season to talk to their vet for advice well before tupping this year, even if diagnostic blood samples have not been taken.