If farmers are beginning to experience an abortion rate of 2-3 per cent or higher, it is time to involve the vet.
Matt Haslam, veterinary surgeon with Benchmark Animal Health, says: “It is essential the vet is involved as early as possible in an abortion outbreak. There are multiple causes of abortion, the majority of which are infectious and it is important farmers know which disease they are encountering so appropriate control plans can be put in place.”
Shepherds should keep hold of any aborted lambs and their foetal membranes so vets can establish which disease is present in the flock.
Mr Haslam says: “Enzootic abortion of ewes, accounting for roughly 50 per cent of all infectious abortions and toxoplasmosis (roughly 25 per cent), are the two most common causes of abortion in the UK sheep flock.
“Enzootic abortion typically presents as late-term abortions, the placental membranes are thickened and often rotten. Toxoplasmosis can present again as late-term abortions, a high barren rate or the birth of weak or mummified fetuses. With toxoplasmosis the placental cotyledons ’buttons’ are often covered in a white ’frosting’. It is essential these materials are sent to veterinary labs so the correct treatment plans can be put in place.”
Vaccines are available for both toxoplasmosis and enzootic abortion.
Should you and your vet reach a diagnosis of infectious abortion in your flock, a vaccination regime should be established. There is only one vaccine for controlling toxoplasmosis in the UK and this can only be used before tupping when the ewe is empty. Therefore, there is little a farmer can do in the face of an outbreak other than maintain good hygiene to try and prevent the spread of the disease.
Rapid disposal of the infected membranes helps to ensure the parasite does not become established on the farm. Unfortunately, once toxoplasmosis is present on-farm, it rarely disappears and annual vaccination of replacement stock is essential.
Farmers do have a bit more control during an EAE outbreak given that a recently re-launched inactivated vaccine can be used in the face of the outbreak.
Mr Haslam says: “Pre-tupping administration of vaccines is still considered gold standard and they are very effective. However, with the inactivated vaccine farmers now have an option to help them in the face of an outbreak.
“Because it is an inactivated vaccine it can be used in pregnant ewes providing they are four weeks post-tupping. The product is licensed for use in the face of an outbreak to aid control of the abortion storm and can help limit the impact on next year’s lambing too.
“It is important for farmers to have good working relationships with their vets throughout the process to ensure that the correct course of action is taken at each stage.”