Abortion in Sheep Flashcards
What are factors contributing to laming/ rearing percentage?
- Fertility (get the ewes pregnant)
- Lamb survival prepartum (abortion)
- Lamb survival-intra partum (dystocia)
- Lamb survival (post partum- neonatal and growing lambs)
- Sheep- infectious disease and parasitic diseases, lots of veterinary involvement
What are causes of abortions?
*Infectious
*Mixed infections
*Non infectious causes (stress)
What are infectious causes of abortion in sheep?
- Chlamydia abortus
- Toxoplasma gondii
- Campylobacter spp
- Listeria monocytogenes
- Salmonella abortus ovis, montevideo, dublin, diarizonae, typhimurium
- Anaplasma phagocytophilia (Tickbourne fever)
- Border disease virus (BDV)
- Schmallenberg virus
- Coxiella burnetti (Q fever)
- Yersinia spp.
- Fungi
- Arcanobacterium pyogenes
- Bluetongue virus (BTV) - not present in UK at moment
- Escherichia coli
What action should be taken with an abortion case?
*Isolate ewe
*Remove contaminated material (dead lamb, placenta) + bedding
*Clean + disinfect area
*Take samples of foetus, placenta + blood samples
*Take details of flock history (Vaccinations, biosecurity + nutrition)
What are the 4 most common causes of abortion in sheep?
- Chlamydia abortus
- Toxoplasma gondii
- Campylobacter spp
- Listeria monocytogenes
What is chlamydia abortus also known as?
Enzootic abortion in ewes
What is Chlamydia abortus?
*Bacterial gram negative cocci
What is the source of chlamydia infections?
***Other aborting ewes
*Carrier ewes - may or may not abort, will shed bacteria at lambing
What is route of infection of chlamydia?
*Oral route - contaminated bedding / pasture
What are the outcomes of exposure in a pregnant ewe? to chlamydia
- if more than 90days = may abort
- If less than 90 days = may abort later - after 90 days or may become latently infected and abort next pregnancy
What are the outcomes of exposure in a non pregnant ewe to chlamydia
*Latent infection may abort the following lambing season
What are the outcomes of exposure in an ewe lamb born to an infected ewe with chlamydia?
*Become infected + abort at their first lambing
What are the outcomes of exposure in an ewe that have aborted to chlamydia
Once aborted most become immune and not abort again, some will become carriers + shed at oestrus + lambing
What is the pathology of chlamydia abortus?
*post 90 days = bacteria replicate in trophoblastic epithelial cells
*Placentitis + thickening + necrosis
*Inflammation of lamb + internal organs
What are clinical signs of chlamydia?
- Abortion after 90 days of pregnancy , often in last month
- Death of lambs or birth of weak lambs or birth of one live and one dead
- Ewes vaginal discharge couple days
- Sheep are rarely ill, however they may develop metritis subsequent to the abortion which can be fatal.
How is chlamydia abortus diagnosed?
*Abortion in late pregnancy
*Modified ziehl neelsen stain on placenta / fetus
*Bacterial culture
*PCR
What is control of chlamydia during an outbreak?
1) Stop spread of infection
– Isolate aborted ewes
– Abortion material (submitted for PM ) or disposed of carefully with bedding
– Clean and disinfect pens
– Long acting oxytetracycline (to the aborting ewe)
– ZOONOTIC RISK
2) To reduce further abortions.
– treat remainder of flock with the killed inactivated vaccine
– Or/ Treat all at risk ewes yet to lamb (>90 days) with 20mg/kg oxytetracycline long acting .Repeat in 2 weeks
What is control of chlamydia in the year following an outbreak?
- Vaccinate all ewes pre-tupping
- If consider there is risk of ewes being latently infected from previous year, repeat the oxytetracycline injections to exposed ewes the year following an outbreak (not acceptable after that should be using vaccinations after this)
How is chlamydia prevented?
*Vaccinate
*Clean flock - don’t buy in, breed replacements
How are sheep infected with toxoplasma gondii?
*Ingest sporulated oocyst from pasture
*Sheep become immune if not pregnant
*Pregnant sheep may abort
What are the infection outcomes of toxoplasma gondii?
- Non pregnant = sheep become immune
- Early pregnancy = foetal reabsorption + present as barren ewe
- Mid pregnancy = foetal death / mummification
- Late pregnancy = abortion of freshly dead lambs / birth of live weak lambs with high mortality
In toxo endemically infected flocks what pattern is seen with abortion?
Younger ewes abort - older ewes = immune
What is diagnosis of toxo?
*Serology of foetus placenta
*Gross pathology of placenta = frosted strawberries cotyledons
*Histopathology of foetus + placenta
*IFAT of toxoplasma
*PCR for antigen
What is control of toxo?
*Vaccination = Toxovax
*Biosecurity
What campylobacter can cause abortion in sheep?
*C. fetus fetus
*C. jejuni
What is the source of infection in campylobacter abortions?
*Carrier sheep
*Aborted material
*Contaminated feed / water
*Birds
What are the clinical signs of campylobacter abortion?
*Abortion in last 6 weeks of pregnancy / birth of weak born lambs
*Occurs 1-4 weeks post infection
*Can cause abortions storms
What is the diagnosis of campylobacter?
*Bacterial culture from placenta, fetal stomach + liver
What is control of campylobacter?
*Isolate aborting ewes
*Improve hygiene
*Move to clean pasture
*NO VACCINE
ZOONOTIC
Where is listeria monocytogenes found?
*Widespread in environment - especially silage
What is seen with listeria infection?
*Encephalitis
*Septicaemia
*Abortion
What is diagnosis of listeria?
*Bacterial culture from aborted lambs / placenta
How is listeria infection controlled?
*Isolate
*Remove contaminated feed
*Antibiotics
What is border disease virus?
*Flavivirus
*Closely related to BVD + classical swine fever
*Most outbreaks of border disease caused by close proximity to PI cattle with BVD
How is border disease virus BDV infection introduced?
*Persistent infected BDV sheep bought in
*Close proximity to BVD PI cow
What is transmission of BDV?
– Oro-nasal route – horizontal transmission
– In utero - vertical transmission
– Semen of persistently infected rams
What are clinical signs of BDV?
*Non pregnant ewes = no clinical signs
*Pregnant ewes = – Abortions (mid pregnancy infection)
– Still births, small weak lambs (mid pregnancy infection)
– Live hairy shaker lambs, (mid pregnancy infection)
– Birth of persistently infected lambs (PI)
– In an infected flock expect about 0.3-0.6% of lambs born to be PI . PI lambs will have reduced growth and increased susceptibility to infections
What is seen with BDV less than 60 days of pregnancy?
– Foetal death, resorption, mummification, abortion, still birth
– Up to 50% foetuses will survive and be normal
What is seen 60-85days pregnancy with BDV?
– Foetal death, abortion, still birth
– Hairy shaker lambs born alive
* Encephalitis (cerebral hypoplasia, ataxia, hypermetria)
* Long limbs
– Small weak lambs
– P.I – can look normal* maintain the infection
What is seen after 85 days of pregnancy with BDV?
– Normally ewe and lamb will be antibody positive and immune
How is BDV diagnosed?
*Serology of ewes with BDV antibodies
*Suspect PI can be tested from 3 months of age by PCR of antigen
How is border disease controlled?
*NO vaccine
*Remove PI’s from flock
*Auto-vaccinate = mix sheep together when non pregnant + hope PI animal expose flock to virus + become immune
What is a tick borne fever?
Anaplasma phagocytophilia
What are the clinical signs of Anaplasma phagocytophilia?
– Fever
– Infertility ewes and rams
– Abortion
– Often seen in naïve animals to a tick area (ie bought in ewes, rams), may occur as a storm in this group
How are the ticks controlled?
*OP dip - diazinon
*Pyrethroids
*Avoid introduction of naive sheep at pregnant / tupping time
How are the ticks controlled?
*OP dip - diazinon
*Pyrethroids
*Avoid introduction of naive sheep at pregnant / tupping time
What are salmonella abortion species?
*S. abortus ovis
*S. montevideo
S. dublin
*S. diarizonae
*S. typhimurium
What are clinical signs of salmonella?
– Abortion last 1/3 pregnancy
– Ewes are often systemically ill
– Can cause abortion storms
How is salmonella diagnosed?
Culture of aborted material
How is salmonella treated / controlled?
*Reduce spread
*Antibiotic tx - oxytetrecycline
*Prevention
How is schmallenberg transmitted?
Midges - culicoides
What are signs of schmallenberg virus?
- Depends on stage of pregnancy when ewe is exposed to infected midges
- Not pregnant then no clinical signs
- As transmitted by midges, when the tupping period occurs in a flock will have a big effect on impact on flock
- ie tupping in October / November, few midges around when ewes pregnant, low or zero impact
- Often problems are seen early lambing flocks where ewes are pregnant in midge season (summer autumn)
- Main clinical sign is foetal malformations
- Dam is pregnant when infected with virus see congenital malformations/ abnormal lambs
- The window for infection of the fetus is short in sheep – 26 to 56 days pregnancy
- Animals can be born alive or dead or aborted
- Numbers of lambs born affected variable depending on lambing season
- Some cases >25% of births abnormal (early lambing)
How is schmallenberg samples diagnosed?
Samples to lab
What is Q fever?
*Coxiella burnettii
-obligate intracellular bacterial pathogen
-very resistant to environment
What does Q fever cause?
*Abortion storms
*Still births
*Poor lambs
How is Q fever diagnosed?
Serology - ELISA
What is control of Q fever?
*Isolation of infected animals
*Oxytetracycline injectable
*Pasteurisation of milk
