Sheep abortions Flashcards
Enzootic Abortion of Ewes (EAE)- Chlamydophila abortus
- ‘Abortion storm’
- 52% infectious abortions £20 million a year to sheep industry
- Route of infection:
- uterine discharge and aborted material, faeces on skin of neonates.
- Clinical signs:
- abortion/ birth of FRESH dead or weak lambs during LAST 3 WEEKS of gestation. Live lambs rarely survive more than a few hours.
- Diagnosis:
- detection of antigenic or nucleic acid in abortion products or vaginal excretions.
- Prevention and control:
- -maintain a clean flock
- strict biosecurity
- -vaccination
- isolate aborted sheep for 3-4 weeks
- long-acting oxytetracycline injection reduce risk of further abortions of other ewes in the group *very few reports in humans.
Toxoplasmosis
- Toxoplasma gondii
- Responsible for 25% infectious abortions
- £12 million a year to sheep industry
Route: feed hay or pasture contaminated with cat faeces containing the parasite (protazoa). Clinical signs: Early pregnancy - embryo reabsorbed (up to 50 days) Mid pregnancy - foetus dies and mummified (50-120days) Late pregnancy - full term still born or weak lambs (>120 days) Ewes infected with toxo develop a strong immunity and are unlikely to abort due to this again. Diagnosis: changes in placenta and antibodies in ewes blood (latex agglutination), fetal fluids and newborn lambs (before colostrum). Blood sampling ewe alone not enough as indicates past infection, not current infection. *It may take a month for antibodies to become detectable in serum, so timing of sampling is important for correct diagnosis* Prevention and control: - sheep feed should be vermin proof and cat proof - Vaccination (administer 3 weeks before breeding season)
Campylobacteriosis
- (campylobater fetus and jejuni)
- 9% infectious abortions
Route: carrier animal (sheep-sheep, birds), contaminated feed/water, aborted material. Clinical signs: abortion 1-3 weeks following exposure to pathogen. Abortion during LATE gestation although some lambs carried to full-term. Diagnosis: samples of foetal LIVER for campylobacter culture or PCR, placenta or materal vaginal discharges, or formalin-fixed specimens of foetal liver for histo. Control and prevention: - clean environments - purchased sheep should be managed as a separate group until after lambing - isolate all aborted ewes - A vaccine can be imported into the UK under license *once infected, lifelong immunity develops.
Salmonellosis
- (Montevideo (no systemic illness), Dublin, Typhimurium (enteric and systemic signs), S.abortus ovis (60% ewes may abort)
Route: feedstuff/ water courses, sewage effluent, carrier cattle, vermin and carrion. Clinical signs: abortion and death in pregnant ewes. Sheep may be found dead with rotten lamb in womb. Diagnosis: culture (MacConkey’s agar, gram-ve) products of abortion, faecal gut contents and internal organs. REPORTABLE DISEASE. Control and prevention: - all feed vermin-proof. sheep should be fed in troughs which are tipped over and moved after feeding. - water from mains supply and ponds/surface water fenced off - Pregnant sheep managed separately from cattle - Whole group long-acting oxytetracycline injections reduces number of abortions during an outbreak. - Vaccine (off-license in sheep, licensed in cattle)
Border disease virus (BDV) - pestivirus
Route: PI sheep bought onto the farm or replacement pregnant ewe carrying an infected foeuts Clinical signs: - high barren rates - early pregnancy (<60 days) - foetal death, mummification, abortion. Some will survive as PI - ‘hairy shakers’ - 60-80 days, outcome hard to predict. Lambs are strong antibody +ve and may have neurological signs. - >85 days, fetus is immunocompetent, some foetuses will die, others will survive and have Abs to BDV. Diagnosis: PCR or virus isolation from foetal tissues such as spleen, histopathoogy of brain. Prevention: - Closed flock, biosecurity - Test incoming sheep - Do not co-graze pregnant ewes with cattle - NO VACCINE
Listeria
Found in the environment in vegetation and decaying soil Abortion can occur at any stage of pregnancy. Aborting ewes are rarely unwell. Diagnosis: - Miliary lesions on the liver - white, yellow foci - enlargement of mesenteric lymph nodes - Gram +ve bacteria smear of foetal stomach contents Prevention: - Antibiotics - Good quality silage - Remove un-eaten silage
Coxiella brunetti
Tick transmission and spores in the ground. Causes abortion in the LAST WEEK of pregnancy, but the birth of live lambs is also seen. Zoonotic potential. Diagnosis: Ziehl-Neelsen stain smears of placenta and foetal stomach contents. Serology of histopathology. PCR of milk, faeces or vaginal swabs. Prevention: - tetracyclines - NO VACCINE
Notifiable causes of abortion:
Brucella ovis Bluetongue virus
Ideal samples to collect:
- Abortive material including fetus and placenta - Section of the placenta with >1 cotyledon - foetal fluid collected from the abdomen or thorax - Aseptic collection of the foetal stomach content - Fresh foetal spleen
Vaccination against infectious diseases:
- Enzovac (EAE) - not less than 4 weeks before mating - Toxovac (Toxoplasma) - not less than 3 weeks before mating DO NOT GIVE THESE WHILST PREGNANT! - Heptovac - clostridia and pasteurella - Footvax (every 6 months) - 4 weeks before housing
What to do with a ewe that has aborted?
- Isolate and permanently mark ewe 2. Adhere to strict biosecurity procedures, including disinfection and deal with infected materials 3. Collect samples of the foetus/lamb and afterbirth, arrange test with vet 4. Dispose of bedding and other infected materials carefully 5. Reduce stocking rate to reduce risk of infection 6. Once cause has been identified, consult with a vet for best treatment and control methods. 7. Vaccinate flock, if vaccine available.
Anaplasma Phagocytophilum Rickettsial organism that parasitizes WBCs (tickborne fever)
- Diagnosis:
- Haematological examination
- Examine brain - eosinophilic multifocal leucomalacia and glial nuclear loss
- maternal serology - ELISA
- PCR
- Prevention:
- Tetracyclines
- Dipping, pour-ons
Leptospira Hardjo
RARE Diagnosis: - PCR - Serotype isolation - Dark vaginal discharge
Neospora Caninum
Rare in sheep, more common in cattle. Oocysts shed in dog faeces (definitive host). Diagnosis: - Histopathology of brain (non-suppurative meningitis) - Immunohistochemistry *No zoonotic potential Prevention: - NO VACCINE - Prevent scavenging dogs eating placentas or dead lambs
Brucella Melitensis
- 16% abortion rate in flocks
Nasopharyngeal route through skin abrasions or mucus membranes. Shed in vaginal fluid 2 months after abortion. Causes orchitis in rams (B.ovis). Diagnosis: virus isolation from placental and foetal stomach contents, ELISA, agglutination Prevention: Vaccinations and culling
