Although the spring weather has still to appear lambing time is well underway. Since January, Ayr DSC has received 51 submissions of ovine abortion material from 39 farms. A diagnosis has been reached in 59% of submissions with the most common diagnosis being Chlamydia abortus the causal agent of Enzootic Abortion in Ewes (EAE) as demonstrated in figure 1. Figure 1 also shows further common causes of ovine abortion. The category ‘other’ encompasses sporadic bacterial and fungal causes of abortion; some of which are feed associated.
Figure 1: Farm level diagnoses of ovine abortion made by Ayr DSC
The overall diagnostic rate rose to 75% in cases where multiple submissions were received from the same farm. This demonstrates the usefulness of further submissions where no diagnosis is reached initially. Additional submissions and a larger volume of abortion material is likely to reduce the difficulties associated with decomposition and increase the chance of isolating infectious agents.
In many of the cases where a diagnosis has not been reached, material has been autolysed or no placenta has been available which severely limits investigation. In other cases histopathology has revealed pathology such as a placentitis. Submission of further material in these cases may have revealed an infectious aetiology.
Many ewes are reported to be in poor body condition. This, in conjunction with current or previous high fluke challenge may also lead to stillbirths, abortions, weak lambs or even a previous high barren rate. It is important however not to assume that this is due to poor condition and a full investigation should be carried out. If no abortion material is available high barren rates can be investigated through serology for toxoplasmosis and EAE.
Submission of multiple foetuses per dam is more cost effective as ovine abortion investigations are charged on a dam basis at £41.20 plus disposal. A batch charge of £61.80 plus disposal is applied where material from more than one dam is supplied.
A previous BVA In Practice series “Abortion in sheep: Investigation and principle causes” and “Abortion in sheep: Other common and exotic causes” is a good reference source.
Abortion in Sheep
1. Investigation and Principal Causes
2. Other Common and Exotic Causes