It’s likely that an insidious infectious disease was a significant cause of barrenness or abortion in ewes last year, according to an analysis of the latest diagnostic results released by MSD Animal Health.
Blood samples from UK sheep farms were tested during 2016 when the subsidised EXPERTIS® FlockCheck diagnostic service was made available to vets between March and July last year.
Toxoplasmosis in flocks
According to the data, 79 percent of the flocks tested showed evidence of exposure to the parasite Toxoplasma gondii, which causes toxoplasmosis. The data also show that 76 percent of flocks had been exposed to Chlamydophila abortus bacteria, the organism causing enzootic abortion (EAE); 60 percent of flocks had 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 (81%) for exposure to Toxoplasma gondii,” says MSD Animal Health livestock veterinary adviser Stephanie Small.
Ms Small says this data highlights the continuing 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.
“Toxoplasmosis, in particular, remains a key cause of barrenness and abortion in UK sheep flocks. It also causes reabsorptions, 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. Toxoplasmosis 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 says.
Enzootic abortion (EAE)
Another underlying disease problem that often manifests itself as significant early lamb losses is enzootic abortion (EAE).
“EAE is caused by Chlamydophila abortus bacteria. The disease can cause devastating abortion storms affecting approximately 25 percent of ewes. Once a flock has the disease it is likely it will never disappear due to its persistence in carrier sheep. The disease often arrives on farm through 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.”
Pre-tupping vaccination advice
Ms Small urges any sheep producers who recorded a flock barren rate greater than two percent last season to talk to their vet for advice well before tupping this year, even if diagnostic blood samples have not been taken. Ask for help too if any ewes aborted lambs during lambing, she says.
“If either toxoplasmosis or EAE has been diagnosed in a flock, vaccination is the most effective way to help protect against these diseases for future years. The TOXOVAX® toxoplasmosis vaccine is known to protect the ewe for at least two lambing seasons and, conveniently, can be given to breeding females at any time between four months and four weeks before tupping.
“The ENZOVAX® vaccine helps protect the ewe for at least three years against EAE and all breeding females should be vaccinated any time between four months and three weeks before tupping,” Ms Small advises.
Always use medicines responsibly and consult your veterinary surgeon prior to use . For more information visit: www.noah.co.uk/responsible
TOXOVAX® and ENZOVAX® are only available from veterinary surgeons from whom advice should be sought. Toxovax contains Toxoplasma gondii. Enzovax contains Chlamydophila abortus strain 1B. Legal categories POM-V. EXPERTIS®, TOXOVAX® and ENZOVAX® are the property of Intervet International B.V. or affiliated companies or licensors and are protected by copyrights, trademark and other intellectual property laws. Copyright © 2017 Intervet International B.V. All rights reserved.
Further information is also available from MSD Animal Health.