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Ovine Abortion Flashcards

1
Q

What are the three most common causes of ovine abortion in NZ?`

A
  • Campylobacter fetus fetus - Toxoplasma gondii - Salmonella brandenberg
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2
Q

What are some less common causes of ovine abortion in NZ?

A
  • Listeria monocytogenes - Yersinia - Bacillus - Hairy shaker disease
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3
Q

What are some causes of ovine abortion overseas?

A
  • Enzootic abortion - chlamydia psittaci - Schmallenberg virus
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4
Q

Describe campylobacter fetus fetus abortion…

A
  • Only associated with late gestation losses - Prevent throughout world - NZ has high prevalence - Bacterial disease
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5
Q

Describe the epidemiology of campylobacter fetus fetus…

A
  • Believed to be introduced by carrier sheep - Affects MA ewes and young sheep - Transmitted by ingestion, in feed and water or from direct contact with aborted faeces - Can survive in environment for ~20days - Shepherds can transmit bacteria - Seagulls can too - No sexual transmission
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6
Q

Describe the pathogenesis of campylobacter fetus fetus…

A
  • Post infection bacteraemia occurs and the bacteria invades and localises in the placenta and foetus - Bacterial growth enhanced by placental blood supply - Placentitis develops which results in patchy necrosis on placenta and foetal tissues - Fetus dies - Infected ewes may become carriers - Ewe post infection ewes become immune
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7
Q

What are the clinical features of campylobacter fetus fetus?

A
  • Most common cause of abortion storms - Abortion usually in last 6 weeks of pregnancy - Healthy ewes - Early neonatal loss - birth of weak lambs - Ewes remain immune for years afterwards
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8
Q

What will the farmer find if they come across a campylobacter fetus fetus?

A
  • Often have huge abortion storms - May just see ewes with blood on perineum or membranes protruding - Always happens after 3 months gestation - Most often occurs in maiden ewes - Some ewes carry infected lambs to full term = weak neonates with poor survival - Often get outbreaks after ewes have been stressed and grazed at high stocking rates
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9
Q

How do you diagnose campylobacter fetus fetus?

A
  • Gross lesions will be seen – necrotic liver lesions occur in about 20-30% of foetus - Foetus usually looks fresh - PM - microscopy of foetal stomach contents - Culture of foetal stomach contents or placenta
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10
Q

How do you control campylobacter fetus fetus Ovine abortions ?

A
  • Reduce exposure to infected pasture - Vaccinate early in the outbreak - Antibiotics not practical, but can be used on expensive ewes
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11
Q

Describe the campylobacter fetus fetus vaccine…

A

Campylovexin - Inactivated/ killed vaccine – give two doses to maiden and bought in ewes 4-6 weeks apart and again in pre-mating/ early pregnancy period - 1mL dose SC in neck - Annual booster

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12
Q

Are all ‘Campylobacter’ Abortions caused by C. fetus fetus?

A

No - there is also another campylobacter strain called C. jejuni

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13
Q

Describe C.jejuni abortions in ewes…

A
  • Sporadic Abortions - Unknown prevalence - Bird contamination the cause??? unknown - No cross-protection from C. fetus fetus vaccines - Campy VAX 4 includes both - C. jejuni elicits an antibody response
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14
Q

Describe the Epidemiology of Toxoplasma, gondii abortion…

A
  • Common in NZ and worldwide - Can infect with Campylobacter - Protozoan - Mice are reservoir hosts for cats - Resistant oocytes contaminate hay, bedding, concentrates where Faecal-oral route infects route - Once infected immunity is lifelong
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15
Q

In what ewes do you see T.gondii abortions most?

A

In maiden ewes or naive flocks - due to immunity being lifelong

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16
Q

What is the time from infection with T.gondii to abortion?

A

40 days

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17
Q

What else can be infective apart from faecal-oral route of T.gondii?

A

Ram Semen!

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18
Q

What are the clinical signs of T. gondii infection in ewes?

A

Early - EED - late return to oestrus or dry-dry ewes Mid - Undeveloped fetal immune system - Fetal death - Mummification - Abortion Late - Immune competency in fetus - Born immune - Lambs are normal

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19
Q

Are there any signs in ewes of T.gondii infection?

A

No - there are no systemic signs in ewes

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20
Q

How do you diagnose T.gondii infection?

A
  • Gross lesions - Mummified foetus - Strawberry cotyledons - Histopath of cotyledons, foetal lung, liver and brain - Indirect fluorescent antibody test on foetal fluid - Sera from ewe
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21
Q

How do you control T.gondii infection?

A
  • Limit the breeding cat population! - Vaccinate with toxovax – Live vaccine – 2mL dose into neck – short shelf life – single dose to maiden ewes confers life long immunity – Give more than 4 weeks before mating and not during pregnancy
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22
Q

Describe the epidemiology of Salmonella Brandenburg…

A
  • Emerging cause of ovine abortion in South Island - Introduced by carrier sheep, gulls etc and dust fomites? - Survives ~>4 months in environment - Ingested in contaminated feed, inhaled on dust? - High stock density leads to increased stress leads to increased shedding - Both MA and 2ths susceptible - often multiple bearing!
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23
Q

Describe the clinical features of Salmonella Brandenburg…

A
  • Abortion in late pregnancy - Foetus autolysed and smelly - Ewe often has difficulty expelling lambs - Ewe sick due to necrotising metritis - ~50% of aborting ewes die
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24
Q

How do you diagnose S. brandenburg infections?

A
  • Location - History - Abortion late gestation with sick ewes and autolysed foetuses - Culture foetal stomach contents - Liver, placenta and vagina swabs - Histopath of placenta
25
Q

How do you treat infection of S. brandenburg?

A
  • V. guarded prognosis - Ewes treated with LA oxytetracycline given early may prevent ewe death but not abortion - Potentiated sulphonamides may be better - daily for 5-7 days - Penicillin + Clavulanic acid + Amoxicillin at high dose for 7 days + NSAID + Fluid therapy for sick ewes )v. intensive!) - Enrofloxacillins very effective but expensive
26
Q

How do you control S. brandenburg infection with a vaccine?

A
  • Vaccination with Salvexin + B - Incomplete protection - Inactivated vaccine - 2 doses 4-6 weeks apart, pre mating and in early preg - Annual Booster - Vaccinate in face of outbreak is recommended
27
Q

How do you control S. brandenburg infection with farm management?

A
  • Vaccinate - Avoid high stocking densities - Minimise pre-lambing yarding and stressors - Avoid purchasing stock from infected properties - Hygiene
28
Q

What do you do in the face of an outbreak of S. brandenburg?

A
  • Spread ewes out to decrease Stocking Rate and F-O contamination - Ensure plenty of clean fresh water and good feed levels - Vaccinate - Try not to stress ewes further
29
Q

What is Hairy Shaker Disease/ Border Disease?

A
  • Pesti virus related to BVD - Transmitted via mucous membranes - Introduced to flock by clinically normal sheep - Surviving lambs + previously affected ewes are sources of infection - Ewes affected last season will breed successfully due to immunity
30
Q

Describe the pathogenesis of Hairy Shaker Disease…

A

Dependent on when pregnant ewe becomes infected - Early gestation: EED - late return to oestrus or dry-dry ewes Mid - Mummification - Abortion Late - Birth of hairy shakers

31
Q

What are some clinical features of Hairy Shaker Disease?

A
  • Embryonic death - Abortion Birth of hairy, stunted lambs - No subsequent decrease in fertility - Outbreaks usually involve the mixing of infected and susceptible flocks at/ soon after mating
32
Q

How do you diagnose HSD?

A
  • Presence of HSD in lambs is usually diagnostic - Live lambs are hairy and stunted - Lambs often have a discoloured patch of hair on the back of the neck or back - ELISA for antigen or antibody serum
33
Q

How do you control Hairy Shaker Disease?

A
  • Avoid exposure of pregnant ewes to infection - Be careful when mixing bought in ewes with existing ewes - Mix new stock months before mating or closely after mating - Cull affected lambs - Cull infected ewes who have HSD lambs consistently!
34
Q

Apart from the three main causes of abortion, what are some other infectious causes?

A
  • Bacillus - Fusobacterium spp - Brucella ovis (rare) - Listeria - Yersinia usually sporadic and opportunistic - Wet muddy paddocks and high stocking density etc. are predisposing factors
35
Q

What is a non-infectious cause of ewe abortion?

A

High nitrate - Rare - Hypoxia

36
Q

What are two international causes of ewe abortion?

A
  • Enzootic Abortion (OEA) - Schmallenburg virus
37
Q

Describe Ovine Enzootic Abortion…

A
  • gm -ve intracellular bacterium Chlamydia abortus - Particularly in UK - Intensely managed flocks over lambing are most at risk - Not in NZ or Aus - Zoonosis - Replacement stock are the source - Starts slow and builds up until many ewes abort - Oral infection - Up to 30% of lambs born to infected ewes are likely to abort themselves next season - Lifelong immunity after aborting - Invades placenta at around 90 days gestation - Necrotising placentitis and abortion - Shed in vaginal fluids and membranes leading to oral infection - Abortions occur in last month of pregnancy - Lambs fresh and well grown when aborted - Placenta thickening ans opacity - Ewes clinically normal + or = vaginal discharge
38
Q

How do you diagnose ovine Enzootic abortion?

A
  • Foetal stomach sample for culture - Foetal brain for histo - ZN stain of placental smears or vaginal swabs - Rising serological titres diagnoses flock exposure - PCR vaginal swabs
39
Q

How do you control ovine enzootic abortion?

A

Vaccination - Live vaccine given 4 weeks prior to mating as a single dose

40
Q

How do you treat ovine enzootic abortion?

A

Oxytetracycline for entire flock 3-6 weeks prior to lambing

41
Q

Describe Schmallenburg virus abortion…

A
  • Orthobunyavirus - Transmitted by Culicoides midges to sheep, goats, cattle and alpacas - Found across Europe and UK
42
Q

Describe the pathogenesis of Schmallenburg virus…

A
  • Culicoides is a biting midge - Stillbirths and abortions in sheep - Congenital malformations – Hydrocephalus – Scoliosis – Arthrogryposis – Enlarged thymus – Cerebella hypoplasia - Dummy lambs: unable to suck, blind, ataxia, convulsions - Infected ewes should develop immunity and not abort the next year
43
Q

How do you diagnose Schmallenburg virus?

A
  • Paired sera collection 3 weeks apart for seroconversion to ID infected flocks (ELISA) - EDTA blood for virus particle detection - PCR from foetal tissues
44
Q

How do you treat Schmallenburg virus?

A

No treatment - No vaccine available

45
Q

How do you control Schmallenburg virus ?

A
  • Housed animals less likely to be bitten by midges - Ecto-parasites may be beneficial
46
Q

What kind of history questions can you ask a farmer if he has an abortion storm?

A
  1. Period in Gestation when client has seen abortions? Toxo vs Campo 2. Number ewes involved? 3. Age of ewes – is it specific to one mob or is it across the entire farm? 4. Ask farmer what do the abortions look like? 5. Any sick ewes? 6. Previous History of farm? – test results from any previous investigations on abortion? 7. Vaccination Policy for Toxo / Campo / Salmonella 8. Introduction of any new animals? 9. Does he have a cat problem?
47
Q

What do you do when you visit a farm that has had an abortion storm?

A
  1. PM lambs on farm or get client to bring them into practice PM room. 2. Take all samples as can have dual infections - Foetal stomach contents – culture + microscopy examination - Foetal liver / lungs / heart blood – culture / IFAT - Foetal Brain / heart / Liver / lung – histology - Placenta – fixed and fresh for culture and histology
48
Q

What is this aborted foetus indicative of?

A

Campylobacter fetus fetus

  • Opaque placenta
  • Foetus usually looks fresh

-

49
Q

What is this liver foetus indicative of?

A
  • Campylobacter fetus fetus abortion
  • Necrotic liver lesions in 20-30% of aborted C. fetus fetus foetuses
50
Q

What are these aborted foetuses indicative of?

A
  • Toxoplasma gondii
  • A mid-pregnancy abortion due to foetal death and mummification
51
Q

What are these aborted foetuses indicative of?

A
  • T.gondii
52
Q

What are these cotyledons indicative of?

A

T. gondii

  • Placental ‘strawberry’ cotyledons
  • White-grey areas of necrosis
53
Q

What is this placenta indicative of?

A
  • T. gondii
  • clear, intercotyledonary areas
  • Should be able to read a newspaper through the membrane
54
Q

What has caused this abortion?

A
  • T.gondii
  • mummification of foetuses
55
Q

What has caused the abortion of these two twins?

A
  • T.gondii abortion
  • Common for one twin to be mummified and the other to look relatively normal
56
Q

What has caused this foetus to abort?

A
  • S. brandenburg infection
  • Foetus is autolysed and smelly
57
Q

What is this?

A

Metritis : inflammed uterus wall

  • Ewe died from infection following S. brandenburg abortion
58
Q

What is this?

A

Placentitis : severe necrotising inflammed placenta

  • Ewe died from infection following S. brandenburg abortion
59
Q

What is wrong with this lamb?

A
  • Has Hairy Shaker Disease
  • Ewe was infected with pesti virus in late pregnancy
  • Lambs are hairy and stunted in growth

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