Abortion (Yr4) Flashcards
what is the gestation of a sheep?
150 days
what causes enzootic abortion?
Chlamydia abortus
what is the route of infection of Chlamydia abortus (enzootic abortion)?
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
what are the different possible outcomes if sheep are exposed to Chlamydia abortus?
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
how would a naive flock to Chlamydia abortus be effected if it was introduced?
first year there would be low abortion rates (just in the bought in sheep)
following years there could be massive abortion storms
how does Chlamydia abortus cause abortion?
replicates im trophoblastic epithelial cells present after 90 days, it causes severe placentitis effecting nutrients/hormones leading to death or damage to lambs
when do abortions from Chlamydia abortus occur?
after 90 days (often the last month)
how can Chlamydia abortus be diagnosed?
ziehl nielson staining of placenta, foetus or vaginal discharge
bacterial culture or PCR
how can Chlamydia abortus abortions be reduced/controlled if occurring in a flock?
vaccinate
treat at risk ewes >90 days with 2 doses of LA oxytetracycline
how should Chlamydia abortus be treated in the year following an outbreak?
vaccinate all ewes pre-tupping
what is the definitive host of Toxoplasma gondii?
cats
what is the rough lifecycle of Toxoplasma gondii?
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
what are the possible outcomes when sheep become infected with Toxoplasma gondii?
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
what are the main group of animals you see abortion in from Toxoplasma gondii?
younger ewes (gain immunity after abortion and if infected when not pregnant)
can ewes become immune to Toxoplasma gondii?
yes… once aborted or if infected when non-pregnant
what is the typical gross pathology associated with Toxoplasma gondii?
frosted strawberry cotyledons
how can Toxoplasma gondii be controlled?
control cat/rodent population
toxovax given 3 weeks prior to tupping
what species of campylobacter can cause abortion?
Campylobacter fetus fetus
Campylobacter jejuni
what are the possible sources of infection of Campylobacter spp.?
carrier sheep
aborted material
contaminated feed/water
birds
when do Campylobacter spp. cause abortions?
last 6 weeks of pregnancy (or weak lambs)
how can Campylobacter spp. effect the ewe?
can become ill with metritis
how is BVD usually introduced to a flock?
bringing in a PI animal
how can BDV be transmitted?
oro-nasal route (horizontal)
in utero (vertical)
semen in PI rams
what are the possible presentation of BDV?
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
how can BDV be diagnosed?
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
what causes tick borne fever?
Anaplasma phagocytophilia
what are some possible clinical signs of Anaplasma phagocytophilia (tick borne fever)?
immunosuppressive so many syndromes…
fever
infertile rams/ewes
abortions
how can tick borne fever be controlled?
treat sheep with pyrethroid pour on or organophosphate dip before entering tick areas
don’t introduce naive sheep around tupping or when pregnant
when does Salmonella cause abortions?
lat 1/3 of pregnancy (ewes often systemically ill with it)
what antibiotic should be used in aborted, sick or at risk sheep for Salmonella?
LA oxytetracycline
what transits schmallenberg virus?
culicoides midge
what flocks are more at risk of Schmallenberg virus?
those that have an earlier lambing season, tupping earlier means there will still be midges about
what is that at risk period when foetus can be come infected with Schmallenberg?
26-56 days of gestation
what causes Q fever?
Coxiella burnetti
what does Q fever cause?
abortion, still births and poor lambs
