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The Oak Veterinary Practice
The 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 Ewes
Infectious 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
Abortion
Enzootic 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.
Biocontainment
Reduce/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 abortion
Enzootic 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 drawnup 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.
Normal foetus
Foetal resorption
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.
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
B
C
D
Above one per cent
Above two per cent
Above five per cent
Above eight per cent
What abortion rate is suggestive of an infectious cause:
A
B
C
D
Above one per cent
Above two per cent
Above five per cent
Above eight per cent
Answer
B
What is the likely cost of abortion:
A
D
D
D
£2 to £5 per aborted ewe
£5 to £10 per aborted ewe
£10 to £20 per aborted ewe
£20 to £65 per aborted ewe
What is the likely cost of abortion:
A
D
D
D
£2 to £5 per aborted ewe
£5 to £10 per aborted ewe
£10 to £20 per aborted ewe
£20 to £65 per aborted ewe
Answer
D
A zoonotic infection is defined as:
A
B
C
D
The spread of an infection from animals to humans
The spread of infection from one sheep to another sheep
The ability of an infection to remain dormant for many
months
An infection that is resistant to antibiotic therapy
A zoonotic infection is defined as:
A
B
C
D
The spread of an infection from animals to humans
The spread of infection from one sheep to another sheep
The ability of an infection to remain dormant for many
months
An infection that is resistant to antibiotic therapy
Answer
A
Which infectious agent can cause a high barren rate in susceptible
sheep:
A
B
C
D
Enzootic abortion of ewes,
Salmonella spp.
Toxoplasma gondii
Campylobacter species
Which infectious agent can cause a high barren rate in susceptible
sheep:
A
B
C
D
Enzootic abortion of ewes,
Salmonella spp.
Toxoplasma gondii
Campylobacter species
Answer
C
EAE infection of a pregnant ewe less six weeks from her due
lambing date causes:
A
A
C
D
abortion within several hours
abortion within several days
abortion within several weeks
abortion during her next pregnancy
EAE infection of a pregnant ewe less six weeks from her due
lambing date causes:
A
A
C
D
abortion within several hours
abortion within several days
abortion within several weeks
abortion during her next pregnancy
Answer
D
Which animal is important in the life cycle of Toxoplasmosis:
A
B
C
D
Badgers
Seabirds
Dogs/foxes
Cats
Which animal is important in the life cycle of Toxoplasmosis:
A
B
C
D
Badgers
Seabirds
Dogs/foxes
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
B
C
D
Enzootic abortion of ewes
Salmonella spp.
Toxoplasma gondii
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
B
C
D
Enzootic abortion of ewes
Salmonella spp.
Toxoplasma gondii
Campylobacter species
Answer
C
A highly efficacious vaccine is available against which of the
following common causes of abortion in sheep:
A
B
C
D
Enzootic abortion of ewes
Salmonella spp.
Border Disease
Campylobacter species
A highly efficacious vaccine is available against which of the
following common causes of abortion in sheep:
A
B
C
D
Enzootic abortion of ewes
Salmonella spp.
Border Disease
Campylobacter species
Answer
A
Which of the following statements is consistent with good flock
biosecurity:
A
B
C
D
A closed flock should be maintained wherever possible
Purchased sheep should be mixed with the home flock during
pregnancy to promote immunity by ensuring spread of
infections.
Purchased sheep should be mixed with the home flock in the
lambing shed to promote immunity by ensuring spread of
infections.
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
B
C
D
A closed flock should be maintained wherever possible
Purchased sheep should be mixed with the home flock during
pregnancy to promote immunity by ensuring spread of
infections.
Purchased sheep should be mixed with the home flock in the
lambing shed to promote immunity by ensuring spread of
infections.
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
B
C
D
Purchase ewe lambs from a flock of high health status;
Purchase ewe lambs from a flock of high health status;
vaccinate against EAE and Toxoplasmosis
Purchase ewes and vaccinate against EAE and
Toxoplasmosis
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
B
C
D
Purchase ewe lambs from a flock of high health status;
Purchase ewe lambs from a flock of high health status;
vaccinate against EAE and Toxoplasmosis
Purchase ewes and vaccinate against EAE and
Toxoplasmosis
Purchase ewe lambs from a flock of high health status and
injection with antibiotic during each subsequent pregnancy
Answer
B
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