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
2
Q
What are some less common causes of ovine abortion in NZ?
A
- Listeria monocytogenes - Yersinia - Bacillus - Hairy shaker disease
3
Q
What are some causes of ovine abortion overseas?
A
- Enzootic abortion - chlamydia psittaci - Schmallenberg virus
4
Q
Describe campylobacter fetus fetus abortion…
A
- Only associated with late gestation losses - Prevent throughout world - NZ has high prevalence - Bacterial disease
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
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
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
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
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
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
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
12
Q
Are all ‘Campylobacter’ Abortions caused by C. fetus fetus?
A
No - there is also another campylobacter strain called C. jejuni
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
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
15
Q
In what ewes do you see T.gondii abortions most?
A
In maiden ewes or naive flocks - due to immunity being lifelong
16
Q
What is the time from infection with T.gondii to abortion?
A
40 days
17
Q
What else can be infective apart from faecal-oral route of T.gondii?
A
Ram Semen!
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
19
Q
Are there any signs in ewes of T.gondii infection?
A
No - there are no systemic signs in ewes
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
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
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!
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
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
How do you treat infection of S. brandenburg?
- 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
How do you control S. brandenburg infection with a vaccine?
- 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
How do you control S. brandenburg infection with farm management?
- Vaccinate - Avoid high stocking densities - Minimise pre-lambing yarding and stressors - Avoid purchasing stock from infected properties - Hygiene
28
What do you do in the face of an outbreak of S. brandenburg?
- 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
What is Hairy Shaker Disease/ Border Disease?
- 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
Describe the pathogenesis of Hairy Shaker Disease...
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
What are some clinical features of Hairy Shaker Disease?
- 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
How do you diagnose HSD?
- 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
How do you control Hairy Shaker Disease?
- 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
Apart from the three main causes of abortion, what are some other infectious causes?
- Bacillus - Fusobacterium spp - Brucella ovis (rare) - Listeria - Yersinia usually sporadic and opportunistic - Wet muddy paddocks and high stocking density etc. are predisposing factors
35
What is a non-infectious cause of ewe abortion?
High nitrate - Rare - Hypoxia
36
What are two international causes of ewe abortion?
- Enzootic Abortion (OEA) - Schmallenburg virus
37
Describe Ovine Enzootic Abortion...
- 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
How do you diagnose ovine Enzootic abortion?
- 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
How do you control ovine enzootic abortion?
Vaccination - Live vaccine given 4 weeks prior to mating as a single dose
40
How do you treat ovine enzootic abortion?
Oxytetracycline for entire flock 3-6 weeks prior to lambing
41
Describe Schmallenburg virus abortion...
- Orthobunyavirus - Transmitted by Culicoides midges to sheep, goats, cattle and alpacas - Found across Europe and UK
42
Describe the pathogenesis of Schmallenburg virus...
- 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
How do you diagnose Schmallenburg virus?
- Paired sera collection 3 weeks apart for seroconversion to ID infected flocks (ELISA) - EDTA blood for virus particle detection - PCR from foetal tissues
44
How do you treat Schmallenburg virus?
No treatment - No vaccine available
45
How do you control Schmallenburg virus ?
- Housed animals less likely to be bitten by midges - Ecto-parasites may be beneficial
46
What kind of history questions can you ask a farmer if he has an abortion storm?
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
What do you do when you visit a farm that has had an abortion storm?
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
What is this aborted foetus indicative of?
Campylobacter fetus fetus
- Opaque placenta
- Foetus usually looks fresh
-
49
What is this liver foetus indicative of?
- Campylobacter fetus fetus abortion
- Necrotic liver lesions in 20-30% of aborted C. fetus fetus foetuses
50
What are these aborted foetuses indicative of?
- Toxoplasma gondii
- A mid-pregnancy abortion due to foetal death and mummification
51
What are these aborted foetuses indicative of?
- T.gondii
52
What are these cotyledons indicative of?
T. gondii
- Placental 'strawberry' cotyledons
- White-grey areas of necrosis
53
What is this placenta indicative of?
- T. gondii
- clear, intercotyledonary areas
- Should be able to read a newspaper through the membrane
54
What has caused this abortion?
- T.gondii
- mummification of foetuses
55
What has caused the abortion of these two twins?
- T.gondii abortion
- Common for one twin to be mummified and the other to look relatively normal
56
What has caused this foetus to abort?
- S. brandenburg infection
- Foetus is autolysed and smelly
57
What is this?
Metritis : inflammed uterus wall
- Ewe died from infection following S. brandenburg abortion
58
What is this?
Placentitis : severe necrotising inflammed placenta
- Ewe died from infection following S. brandenburg abortion
59
What is wrong with this lamb?
- Has Hairy Shaker Disease
- Ewe was infected with pesti virus in late pregnancy
- Lambs are hairy and stunted in growth
