Sheep Abortion

Question 1

What % of abortion within a flock is considered a problem?

Answer 1

> 2%

Question 2

Give the most common causes of abortion

Answer 2

Chlamydophila abortus
Toxoplasma
Campylobacter
Salmonella
Listeria
Border disease
E. coli

Question 3

What is the main source of infection of Chlamydophila abortus?

Answer 3

Aborting ewes
Discharges and products of abortion are heavily contaminated, viable for several days
Oral route

Question 4

Give the different outcomes of exposure of Chlamydophila abortus (5)

Answer 4

1) >90 days pregnant: abort
2) <90 days pregnant: wont abort
3) Not pregnant: will harbour infection in reproductive tract and abort the following lambing
4) Ewe lambs born to infected ewes can become infected and abort in their first lambing
5) Once aborted, most ewes become immune and don’t abort again, but some will become carriers and shed at oestrus and lambing

Question 5

Where does Chlamydophila abortus replicate within the ewe?

How does it cause abortion?

Answer 5

Trophoblastic epithelial cells
Causes severe placentitis with thickening and necrosis -> affects transport of nutrients and hormone production -> death or damage to lamb and inflammation of lamb’s organs

Question 6

Give the clinical signs of Chlamydophila abortus

Answer 6

Abortion after 90 days of pregnancy (usually last month)
Death of lambs/birth of weak lambs/birth of one live and one dead lamb
Vaginal discharge for a couple of days
Sheep are rarely ill, occasionally have metritis (can be fatal)

Question 7

How do you diagnose Chlamydophila abortus?

Answer 7

Abortion of well-preserved lambs in late pregnancy
Submit aborted placenta to APHA
Gross pathology: necrotising placentitis, intracotyledonary thickening
Modified Ziehl Neelson stain on placenta/vaginal discharge/foetus
Culture
PCR

Question 8

How do you control an outbreak of Chlamydophila abortus?

Answer 8

Stop spread of infection: burn abortive material and bedding, isolate aborted ewes til discharges have cleared, clean pens

To reduce further abortions: treat all ewes yet to lamb (>90 days) with 20mg/kg long-acting oxytet, repeat in 2 weeks

Vaccinate next year with Enzovax or Cevax chlamydophila (give up to 4 weeks before mating)

Question 9

What is the gestation period of a sheep?

Answer 9

147 days

Question 10

How is Toxoplasma spread?

Answer 10

Cats= definitive hosts
Wildlife= reservoir
Cats shed millions of oocysts in faeces then become immune
Oocysts in environment are ingested by sheep

Question 11

What are the 4 outcomes of Toxoplasma ingestion?

Answer 11

1) Not pregnant: develop immunity
2) Early pregnancy: foetal resorption, ewe appears barren
3) Mid pregnancy: foetal death/retardation/mummification
4) Late pregnancy: abortion/weak lambs/live immune lambs. Depends on lamb’s and placenta’s ability to deal with infection
Aborted ewes become immune

Question 12

How do you diagnose Toxoplasma gondii?

Answer 12

Submit foetus, placenta, or paired blood sample of ewe for serology
Gross pathology of placenta: ‘frosted strawberries’ cotyledons
Histopath of foetus and placenta
IFAT of antigen in placenta
PCR
Serology

Question 13

How would you describe a placenta affected by Toxoplasma gondii?

Answer 13

Frosted strawberry cotyledons

Question 14

How would you describe a placenta affected by Chlamydophila abortus?

Answer 14

Thick and necrotic

Question 15

How would you treat Salmonella abortus in sheep?

Answer 15

Long-acting oxytetracycline (20mg/kg)

Question 16

Which Campylobacter species most commonly causes abortion in sheep?

Answer 16

C. fetus fetus

Question 17

When does Campylobacter cause abortion in sheep?

Answer 17

Last 6 weeks of pregnancy (1-4 weeks post-infection)

Question 18

How do you diagnose Campylobacter?

Answer 18

Smear and culture of placenta/foetal stomach and liver

Question 19

How do you treat Campylobacter?

Answer 19

Broad-spectrum ABs

No vaccine

Question 20

How is Border disease maintained in the flock?

Answer 20

PI animals

Question 21

Describe the outcomes seen with Border disease

Answer 21

<60 days pregnant: foetal death, resorption, mummification, abortion, stillbirth. Up to 50% survive and are normal

60-85 days: foetal death, abortion, stillbirth. Hairy shakers. Small weak lambs. PI lambs (can look normal)

> 85 days: normal but Ab positive lambs

Question 22

How is Schmallenberg spread?

Answer 22

Culicoides midges

Question 23

Give some clinical signs of Schmallenberg in cattle and sheep

Answer 23

Cattle: mild dz, diarrhoea, fever, milk drop, recover in 2-5 days

Sheep: no apparent clinical signs, increased return to service and barren ewe rate

Question 24

Give some birth defects seen with Schmallenberg

Answer 24

Can be born dead/alive/aborted
Bent limbs, fixed joints
Twisted neck/spine
Domed head
Short lower jaw
Live 'dummy'
Blindness
Wobbly
Inability to suck
Fitting

Question 25

Where does Listeria reside?

Answer 25

Soil

Question 26

When does abortion from Listeria occur?

Answer 26

1-2 weeks after feeding affected silage

Question 27

How do you treat Listeria?

Answer 27

Antibiotics for in-contacts (penicillin, oxytet)

Remove contaminated silage

Question 28

What is ‘tick-borne fever’?

How do you treat it?

Answer 28

Anaplasma phagocytophilia
Immunosuppressive, secondary infections
Abortion in naive animals
Tx: pyrethroid pour-on

Question 29

What is ‘Q fever’?

Answer 29

Coxiella burnettii

Question 30

How does Q fever affect pregnant and non-pregnant ewes?

Answer 30

Non-pregnant: clinically silent, then recrudesces when pregnant
Pregnant: abortion, stillbirth, poor lambs