Abortion in Sheep

Enzootic Abortion

Key Points:

• Enzootic Abortion is highly contagious from sheep to sheep.
• 99% of infection takes place around lambing time with ewes and lambs picking the infection up from aborted lambs, infected cleansings and vaginal discharges (which can last for up to 3 weeks) from ewes which have aborted.
• Enzootic Abortion organisms can survive for up to 6 weeks in the environment.
• Once infected a ewe/lamb will carry the infection until she next becomes pregnant and will then abort, usually in the last 2-3 weeks of pregnancy.
• Ewes aborting this year were probably infected at lambing time last year.
• A ewe should only abort once due to Enzootic Abortion but even though she may produce full term lambs in subsequent years, she can still contaminate the environment with infectious vaginal discharges.
• Enzootic Abortion is contagious to humans - pregnant women should stay well away from lambing sheep.
• Rams are not thought to be significant in the spread of Enzootic Abortion.

Action to be taken in the face of an outbreak:

• Isolate ewes which abort from all other sheep (including ewes which have already lambed) until any vaginal discharges have cleared up (approximately 3 weeks).
• Remove aborted lambs and afterbirths from the lambing pens ASAP and destroy any contaminated bedding.
• Injecting 'in contact' ewes (i.e. those in the group which are yet to lamb) with Terramycin LA (1ml per 10kg into muscle as a single injection) will greatly reduce the number of sheep aborting this year.
• Breeding ewes can be vaccinated in the Autumn at least 1 month prior to tupping with a live vaccine (Enzovax or Cevac Chlamydophila).

For further information on Enzootic Abortion in ewes speak to one of the farm animal vets.

Toxoplasma Abortion

Key Points:

• There is no sheep to sheep spread of Toxoplasmosis.
• Sheep become infected if they eat feed (pasture, hay or concentrates) or drink water that is contaminated with cat faeces which contains Toxoplasma.
• Toxoplasma oocysts can survive in the environment for many months.
• Cats become infected by eating small animals (especially mice) which are persistently infected with Toxoplasmosis. Once infected a cat will usually only be contagious for a few weeks after which it will have a lifelong immunity and not be at risk of infecting sheep.
• Infection of sheep in early pregnancy kills the foetus and ewes may present as barren.
• Infection of ewes later in pregnancy may result in abortion, stillbirths and weakly alive lambs, often accompanied by a mummified foetus.
• Following infection sheep are immune and should not abort again due to Toxoplasmosis.
• Toxoplasmosis can also cause serious disease in pregnant women.

Action to be taken in the face of an outbreak:

• Even though there is no direct sheep to sheep spread of Toxoplasmosis it is good policy to isolate aborted ewes from all other sheep until any vaginal discharges have cleared up (approximately 3 weeks), and to remove aborted lambs/afterbirths from the lambing pens in case there is more than one cause of abortion present.
• A vaccine (Toxovax) is available for future years to be administered at least 1 month prior to tupping (vaccine cannot be given to pregnant ewes).
• Anticoccidiostat drugs (Deccox) can be administered to feed to in-lamb ewes in future years to help reduce abortions.
• No drugs are effective in the face of an outbreak to prevent further losses during this lambing time.
• Diagnosis of Toxoplasma Abortion is by examination of aborted lambs and placentas or blood sampling sheep which have aborted. Typically, placentas from ewes which have aborted due to Toxoplasmosis have white spots on the cotyledons (buttons).

For further information on Toxoplasma Abortion in ewes speak to one of the farm animal vets.

Campylobacter Abortion

Key Points:

• Campylobacter Abortion in ewes is caused by infection with the bacteria Campylobacter Foetus Foetus and is highly infectious from ewe to ewe.
• Ewes become infected orally by contact with feed or water infected with Campylobacter or by direct contact with aborted material from other ewes.
• Carrier sheep are believed to be the most important means of introducing the infection into a naive flock although carrion eating birds such as Magpies and Crows and people who have handled aborted material may also play a role in mechanical transmission of Campylobacter.
• Abortion occurs 7-25 days after infection.
• Following infection ewes mount a good immune response and seldom abort a second time due to Campylobacter.
• There is minimal carry-over of infection in the flock from one year to the next.

Action to be taken in the face of an outbreak:

• Unfortunately, treatment in contact ewes with antibiotics is of limited benefit.
• There is no vaccine available in the UK to prevent Campylobacter Abortion.

For further information on Campylobacter Abortion in ewes speak to one of the farm animal vets.