Abortion (Yr4)

Question 1

what is the gestation of a sheep?

Answer 1

150 days

Question 2

what causes enzootic abortion?

Answer 2

Chlamydia abortus

Question 3

what is the route of infection of Chlamydia abortus (enzootic abortion)?

Answer 3

oral route and close contact at lambing from other aborting ewes (discharge and abortion products heavily contaminate the environment)
carrier ewes are a less common source of infection

Question 4

what are the different possible outcomes if sheep are exposed to Chlamydia abortus?

Answer 4

pregnant… >90 days she may abort, <90 days she might abort later of become latently infected and abort next pregnancy
not pregnancy… latently infected and abort next pregnancy
lambs born to infected ewes… can become infected and abort first lamb
ewes previously aborted… they become immune but can be carriers and shed bacteria

Question 5

how would a naive flock to Chlamydia abortus be effected if it was introduced?

Answer 5

first year there would be low abortion rates (just in the bought in sheep)
following years there could be massive abortion storms

Question 6

how does Chlamydia abortus cause abortion?

Answer 6

replicates im trophoblastic epithelial cells present after 90 days, it causes severe placentitis effecting nutrients/hormones leading to death or damage to lambs

Question 7

when do abortions from Chlamydia abortus occur?

Answer 7

after 90 days (often the last month)

Question 8

how can Chlamydia abortus be diagnosed?

Answer 8

ziehl nielson staining of placenta, foetus or vaginal discharge
bacterial culture or PCR

Question 9

how can Chlamydia abortus abortions be reduced/controlled if occurring in a flock?

Answer 9

vaccinate
treat at risk ewes >90 days with 2 doses of LA oxytetracycline

Question 10

how should Chlamydia abortus be treated in the year following an outbreak?

Answer 10

vaccinate all ewes pre-tupping

Question 11

what is the definitive host of Toxoplasma gondii?

Answer 11

cats

Question 12

what is the rough lifecycle of Toxoplasma gondii?

Answer 12

cats are the definitive host, they shed oocysts in faeces which contaminates sheep bedding, water and feed
if they are ingested by pregnant sheep they can cause abortion

Question 13

what are the possible outcomes when sheep become infected with Toxoplasma gondii?

Answer 13

non-pregnant… sheep becomes immune
early pregnancy… foetal resorption will occur and ewe presents as barren
mid pregnancy… foetal death or mummification
later pregnancy… live weak lambs or live immune lambs

Question 14

what are the main group of animals you see abortion in from Toxoplasma gondii?

Answer 14

younger ewes (gain immunity after abortion and if infected when not pregnant)

Question 15

can ewes become immune to Toxoplasma gondii?

Answer 15

yes… once aborted or if infected when non-pregnant

Question 16

what is the typical gross pathology associated with Toxoplasma gondii?

Answer 16

frosted strawberry cotyledons

Question 17

how can Toxoplasma gondii be controlled?

Answer 17

control cat/rodent population
toxovax given 3 weeks prior to tupping

Question 18

what species of campylobacter can cause abortion?

Answer 18

Campylobacter fetus fetus
Campylobacter jejuni

Question 19

what are the possible sources of infection of Campylobacter spp.?

Answer 19

carrier sheep
aborted material
contaminated feed/water
birds

Question 20

when do Campylobacter spp. cause abortions?

Answer 20

last 6 weeks of pregnancy (or weak lambs)

Question 21

how can Campylobacter spp. effect the ewe?

Answer 21

can become ill with metritis

Question 22

how is BVD usually introduced to a flock?

Answer 22

bringing in a PI animal

Question 23

how can BDV be transmitted?

Answer 23

oro-nasal route (horizontal)
in utero (vertical)
semen in PI rams

Question 24

what are the possible presentation of BDV?

Answer 24

infected <60 days pregnant… foetal death, resorption (some survive)
infected 60-85 days pregnant…
foetal death, abortion, hair shakers, small weak lambs, PI lambs
infected after 85 days…
lamb normal but antibody positive

Question 25

how can BDV be diagnosed?

Answer 25

low scanning present and hairy shaker lambs
histology of abortion material
serology of ewe for BDV antibodies
test PI lambs from 3 months old by PCR for antigen

Question 26

what causes tick borne fever?

Answer 26

Anaplasma phagocytophilia

Question 27

what are some possible clinical signs of Anaplasma phagocytophilia (tick borne fever)?

Answer 27

immunosuppressive so many syndromes…
fever
infertile rams/ewes
abortions

Question 28

how can tick borne fever be controlled?

Answer 28

treat sheep with pyrethroid pour on or organophosphate dip before entering tick areas
don’t introduce naive sheep around tupping or when pregnant

Question 29

when does Salmonella cause abortions?

Answer 29

lat 1/3 of pregnancy (ewes often systemically ill with it)

Question 30

what antibiotic should be used in aborted, sick or at risk sheep for Salmonella?

Answer 30

LA oxytetracycline

Question 31

what transits schmallenberg virus?

Answer 31

culicoides midge

Question 32

what flocks are more at risk of Schmallenberg virus?

Answer 32

those that have an earlier lambing season, tupping earlier means there will still be midges about

Question 33

what is that at risk period when foetus can be come infected with Schmallenberg?

Answer 33

26-56 days of gestation

Question 34

what causes Q fever?

Answer 34

Coxiella burnetti

Question 35

what does Q fever cause?

Answer 35

abortion, still births and poor lambs