The Oak Veterinary PracticeThe Oak Veterinary Practice, 45 Port Hill, Hertford, SG14 3EP Telephone : 01992 554559

Sheep Abortion

Presented By: Mike Howe

Content Valid Until: 4 October 2013

Abortion in EwesInfectious causes of abortion are most common after day 100 of pregnancy. While sporadic losses are variably attributed to handling procedures or movement, an abortion rate in excess of two per cent is suggestive of an infectious cause and veterinary investigation is essential at an early stage.

Farmers often attribute abortion to handling procedures, feeding or movement but these are uncommon causes

AbortionEnzootic abortion of ewes, Toxoplasma gondii and Campylobacter species cause over 70 per cent of abortion outbreaks in the UK.

The cost of abortion is variably quoted as £20 to £65 per aborted ewe and likely to be much higher in 2010 with increasing lamb prices.

Biosecurity and biocontainment are words describing programs for infectious disease control.

Biosecurity - reduce/prevent the introduction of new diseases onto your farm operation from outside sources

Biocontainment - reduce/prevent the movement of infectious diseases on your farm

Biosecurity is not just to protect farm animals, it is also to protect you, your family and your farm workers.

Freedom from most infectious causes of abortion is best achieved by maintaining a closed clean flock.

BiocontainmentReduce/prevent the movement of infectious diseases on your farm

In common with all infectious causes of abortion, aborted ewes must be isolated and aborted material and infected bedding removed and destroyed to prevent spread of disease on your farm.

Ewes that give birth to dead/weakly full-term lambs should also be isolated. Ewe lambs fostered on to aborted ewes should not be retained for future breeding.

The potential of many abortion causing agents to infect humans must be stressed to everyone attending sheep on your farm.

Common causes of abortionEnzootic abortion of ewes, Toxoplasma gondii and Campylobacter species cause over 70 per cent of abortion outbreaks in the UK.

Enzootic abortion of ewes (EAE),

Infection typically results in the abortion/birth of fresh dead and/or weakly lambs during the last three weeks of gestation.

Disease is transmitted by ingestion following exposure of susceptible sheep to high levels of infected uterine discharges and aborted material. Infection does not result in abortion in that pregnancy unless the ewe is more than six weeks from her due lambing date, rather infection remains dormant in the sheep until the subsequent pregnancy then causes abortion.

The ewe is not sick and may only be identified by a red/brown vulval discharge staining the wool of the tail/perineum, and a drawn-up abdomen.

Whole flock long-acting oxytetracycline injection (20 mg/kg) may reduce the number of abortions from C. abortus infection

Antibiotic injection may not save the litter of an infected sheep but it usually results in lambs being carried much closer to term and consequently these ewes have reasonable udder development and sufficient milk to nurse a single fostered (male) lamb.

Lambs fostered on to aborted ewes should not be retained for future breeding.

Freedom from C. abortus infection is best achieved by maintaining a closed clean flock with strict biosecurity measures

Vaccination offers an excellent means of control for farms buying breeding replacements from non-accredited sources, and in those flocks with an endemic C. abortus problem.

Vaccination against C. abortus costs £2-3 per dose but must be divided over three pregnancies (at least). The cost of abortion is variably quoted as £20 to £65 per aborted ewe.

Toxoplasmosis

Infection during early pregnancy may be manifest as embryo/early foetal loss with an increased number of returns to service after an irregular extended interval or an increased barren rate, often above 8 to 10 per cent.

Toxoplasma infection during mid pregnancy results in abortion or production of weakly live lambs near term often with a small mummified foetus about 10 cm long.

Foetal resorption

Normal foetus

All sheep feed should be stored in vermin-proof facilities to prevent contamination by cats and other vermin.

Toxoplasma vaccine costs £3 per dose but as a single vaccination effectively provides lifelong immunity costing 50 to 60 pence per pregnancy.

Campylobacteriosis

Campylobacter fetus subspecies fetus and Campylobacter jejuni are common causes of abortion where sheep are managed intensively leading to heavy contamination and unhygienic environments during late gestation.

Sheep should be managed in clean environments and not subjected to unhygienic conditions especially during late gestation. Particular attention should be paid to the feeding troughs/areas.

Purchased sheep must be managed as a separate group until after lambing.

Salmonella Abortion

Salmonella montevideo, Salmonella Dublin and Salmonella typhimurium have been associated with abortion, severe toxaemia, and death in pregnant ewes.

Sheep may simply be found dead with autolytic (rotten) lambs present still in the womb which have not been aborted.

Sheep may simply be found dead with autolytic lambs present still in the womb which have not been aborted.

There are many potential sources of salmonellae in a group of sheep including contaminated surface water - note the midden

There are many potential sources of salmonellae in a group of sheep including contaminated feedstuffs and water courses, sewage effluent overflow, carrier cattle, and carrion.

There are many potential sources of salmonellae in a group of sheep including middens.

There are many potential sources of salmonellae in a group of sheep including carrion/seabirds.

There are many potential sources of salmonellae

If possible pregnant sheep should be managed separately from cattle.

Summary•Many infectious causes of abortion can also infect humans (zoonotic infection)

•An abortion rate in excess of two per cent is suggestive of an infectious cause and veterinary investigation is essential

•All aborted ewes must be isolated immediately

•Aborted material and infected bedding must be removed and destroyed to prevent spread of disease on your farm

•Maintain a closed flock wherever possible

•Purchased all flock replacements as maiden sheep whether ewe lambs or gimmers

•Never buy old pregnant ewes – they are seldom a bargain and always a great disease risk

•The cost of abortion is variably quoted as £20 to £65 per aborted ewe

•Vaccinate all flock replacements against EAE and Toxoplasmosis (costs around £1 per pregnancy)

•All feed must be stored in vermin-proof bins

•Sheep should be managed in clean environments

•Water should be supplied from a mains supply with ponds and surface water fenced off

•If possible pregnant sheep should be managed separately from cattle.

Feed stored on floor

What abortion rate is suggestive of an infectious cause:

A Above one per centB Above two per centC Above five per cent D Above eight per cent

What abortion rate is suggestive of an infectious cause:

A Above one per centB Above two per centC Above five per cent D Above eight per cent

Answer B

What is the likely cost of abortion:

A £2 to £5 per aborted eweD £5 to £10 per aborted ewe D £10 to £20 per aborted eweD £20 to £65 per aborted ewe

What is the likely cost of abortion:

A £2 to £5 per aborted eweD £5 to £10 per aborted ewe D £10 to £20 per aborted eweD £20 to £65 per aborted ewe

Answer D

A zoonotic infection is defined as:

A The spread of an infection from animals to humansB The spread of infection from one sheep to another sheepC The ability of an infection to remain dormant for many

monthsD An infection that is resistant to antibiotic therapy

A zoonotic infection is defined as:

A The spread of an infection from animals to humansB The spread of infection from one sheep to another sheepC The ability of an infection to remain dormant for many

monthsD An infection that is resistant to antibiotic therapy

Answer A

Which infectious agent can cause a high barren rate in susceptible sheep:

A Enzootic abortion of ewes, B Salmonella spp.C Toxoplasma gondii D Campylobacter species

Which infectious agent can cause a high barren rate in susceptible sheep:

A Enzootic abortion of ewes, B Salmonella spp.C Toxoplasma gondii D Campylobacter species

Answer C

EAE infection of a pregnant ewe less six weeks from her due lambing date causes:

A abortion within several hoursA abortion within several daysC abortion within several weeksD abortion during her next pregnancy

EAE infection of a pregnant ewe less six weeks from her due lambing date causes:

A abortion within several hoursA abortion within several daysC abortion within several weeksD abortion during her next pregnancy

Answer D

Which animal is important in the life cycle of Toxoplasmosis:

A BadgersB SeabirdsC Dogs/foxesD Cats

Which animal is important in the life cycle of Toxoplasmosis:

A BadgersB SeabirdsC Dogs/foxesD Cats

Answer D

A 8-10 cm long mummified foetus with a dark brown leathery appearance produced at full-term is suggestive of which infectious cause of abortion:

A Enzootic abortion of ewes B Salmonella spp.C Toxoplasma gondii D Campylobacter species

A 8-10 cm long mummified foetus with a dark brown leathery appearance produced at full-term is suggestive of which infectious cause of abortion:

A Enzootic abortion of ewes B Salmonella spp.C Toxoplasma gondii D Campylobacter species

Answer C

A highly efficacious vaccine is available against which of the following common causes of abortion in sheep:

A Enzootic abortion of ewesB Salmonella spp.C Border Disease D Campylobacter species

A highly efficacious vaccine is available against which of the following common causes of abortion in sheep:

A Enzootic abortion of ewesB Salmonella spp.C Border DiseaseD Campylobacter species

Answer A

Which of the following statements is consistent with good flock biosecurity:

A A closed flock should be maintained wherever possibleB Purchased sheep should be mixed with the home flock during

pregnancy to promote immunity by ensuring spread of infections.

C Purchased sheep should be mixed with the home flock in the lambing shed to promote immunity by ensuring spread of infections.

D Lambs fostered onto to aborted ewes will be immune to future infections and should be kept as breeding replacements

Which of the following statements is consistent with good flock biosecurity:

A A closed flock should be maintained wherever possibleB Purchased sheep should be mixed with the home flock during

pregnancy to promote immunity by ensuring spread of infections.

C Purchased sheep should be mixed with the home flock in the lambing shed to promote immunity by ensuring spread of infections.

D Lambs fostered onto to aborted ewes will be immune to future infections and should be kept as breeding replacements

Answer A

If replacement female breeding sheep are essential, which of the following protocols would present least risk for abortion:

A Purchase ewe lambs from a flock of high health status; B Purchase ewe lambs from a flock of high health status;

vaccinate against EAE and ToxoplasmosisC Purchase ewes and vaccinate against EAE and

ToxoplasmosisD Purchase ewe lambs from a flock of high health status and

injection with antibiotic during each subsequent pregnancy

If replacement female breeding sheep are essential, the following protocol would present least risk for abortion:

A Purchase ewe lambs from a flock of high health status; B Purchase ewe lambs from a flock of high health status;

vaccinate against EAE and ToxoplasmosisC Purchase ewes and vaccinate against EAE and

ToxoplasmosisD Purchase ewe lambs from a flock of high health status and

injection with antibiotic during each subsequent pregnancy

Answer B

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