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FARM ANIMAL > 17.4.3: Farm animal abortion > Flashcards

17.4.3: Farm animal abortion Flashcards

1
Q

Which is more common in cattle:
a) abortion due to an infectious cause
b) abortion due to a non-infectious cause

A

b) abortion due to a non-infectious cause

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2
Q

Which is more common in sheep:
a) abortion due to an infectious cause
b) abortion due to a non-infectious cause

A

a) abortion due to an infectious cause

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3
Q

True/false: abortion is the main cause of reproductive failure in cattle.

A

False
Early embryonic death is the main cause of reproductive failure in cattle.

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4
Q

What are some possible non-infectious causes of abortion?

A
  • Hereditary disorders/congenital defects
  • Teratogens e.g. plants (lupins)
  • Poisons e.g. ergot, nitrates, brassicae, mycotoxins, hemlock
  • Trauma/physical factors
  • Prostaglandins: endogenous (stress/inflammation/pyrexia) or exogenous
  • Nutritional deficiencies e.g. severe starvation, Vitamin A, Iodine, Selenium
  • God only knows
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5
Q

Any systemic infection can make a cow lose her calf if it leads to sufficient ________________ release to cause regression of the corpus luteum.

A

Any systemic infection can make a cow lose her calf if it leads to sufficient prostaglandin release to cause regression of the corpus luteum.

In these cases it is important to take a good history of the dam’s health as there may be nothing wrong with the foetus.

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6
Q

Of the following bacterial causes of abortion in cattle, which ones are zoonotic and notifiable?
1. Leptospira hardjo
2. Salmonella spp.
3. Bacillus licheniformis
4. Listeria monocytogenes
5. Brucella abortus
6. Trueperella (Arcanobacter) pyogenes

A

All are zoonotic and notifiable.

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7
Q

Of the following viral causes of abortion in cattle, which ones are notifiable?
1. BVD
2. IBR

A

Neither

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8
Q

What is a possible protozoal cause of abortion in cattle and is it notifiable?

A

Neospora caninum
Not notifiable

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9
Q

What is a possible fungal cause of abortion in cattle and is it notifiable?

A

Aspergillus
Not notifiable

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10
Q

True/false: typically a foetus is expelled immediately after the dam has come into contact with a toxin.

A

False
It may take weeks-months for the foetus to be expelled so the cause of the abortion may be a historical issue.

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11
Q

Which is easier to diagnose:
a) infectious causes of abortion
b) non-infectious causes of abortion

A

a) infectious causes of abortion

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12
Q

What is the causative agent of EAE?

A

EAE: enzootic abortion of ewes
Causative agent: Chlamydia abortus

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13
Q

Describe the characteristics of Chlamydia abortus, and when abortion generally occurs with this pathogen

A
  • Chalmydia abortus: gram-negative, intracellular bacterium
  • Abortion is generally in the last 3 weeks of gestation
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14
Q

How is EAE transmitted and how does it infect ewes?

A
  • Infection is oral
  • Animals affected before or during pregnancy may abort
  • Organism is spread in aborted material and venereal fluids
  • Some ewes become carriers and may excrete organism in their faeces (this is uncommon)
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15
Q

True/false: if animals are infected with Chlamydia abortus before pregnancy, they will not abort.

A

False
Animals infected before or during pregnancy may abort

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16
Q

True/false: Toxoplasma can be transmitted directly from one sheep to another.

A

False
Cats are the definitive host; sheep and other mammals are intermediate hosts.
Toxoplasma cannot pass directly from one sheep to another.

17
Q

What is the result if non-pregnant sheep are infected with Toxoplasma?

A
  • If non-pregnant sheep are infected, they form immunity.
18
Q

What are the most common causes of abortion in sheep? Of these, which are zoonotic?

A
  • Most common: EAE (causative agent Chlamyophila abortus) - zoonotic
  • Second most common: Toxoplasma - zoonotic
19
Q

What type of organism is Toxoplasma? How does it infect sheep?

A
  • Toxoplasma = protozoal parasite
  • Infection occurs through ingestion of oocytes shed in cat faeces
20
Q

What effect does Toxoplasma have on pregnancy?

A
  • Toxoplasma can cause infertility, mummification, stillbirth, and abortion, depending on the stage of gestation and infective dose
21
Q

Which species of Campylobacter cause abortion in sheep and cattle? What type of organism is this?

A

Campylobacter jejuni and Campylobacter foetus foetus

Campylobacter is a gram -ve bacteria.

22
Q

Describe the difference between Campylobacter spread in sheep and cattle

A
  • Campylobacter spreads from sheep to sheep (e.g. via aborted material)
  • Campylobacter spreads venereally in cattle (bull to cow)
23
Q

What is the effect of Campylobacter infection in a group of pregnant ewes?

A
  • Infection during pregnancy results in abortion 7-25 days later, followed by strong immunity
  • Abortions occur in the last 6 weeks of gestation and weak lambs born alive
  • May see diarrhoea as well as abortion
  • Up to 25% of ewes may abort in naïve flocks
  • Can see waves of disease every 4-5 years as immunity wanes in individuals and through addition of naïve animals to the flock
24
Q

What gross placental lesions would you expect with EAE infection?

A

Thickening of the placenta between cotyledons (placentitis) and brown exudate

25
Q

What gross placental lesions would you expect with Toxoplasma infection?

A
  • Dark cotyledons and white speckles of necrosis
  • Inter-cotyledonary area grossly normal
26
Q

If you have a number of barren ewes at scanning, what could you do immediately relevant to an infertility investigation?

A
  • Take blood from these barren ewes at scanning
  • Serology is no substitute for a PM but could be useful
27
Q

Grey areas of necrosis on foetal lamb livers are pathognomonic for which infectious agent?

A

These lesions are not pathognomonic - many bacterial infections can cause this.

28
Q

What immediate control actions could you take in the case of several abortions in a group of ewes? Which infectious agents are each of these steps relevant for?

A
  • Isolate the ewe (not required for Toxoplasmosis but a sensible precaution)
  • Treat any systemic diseases
  • Don’t foster on any lambs (especially ewe lambs that may be kept as replacements) to affected ewes - EAE risk
  • Mark ewes so that they can be can identified for serology at a later date if required
  • Maintain good hygiene and biosecurity (i.e. cleaning and disinfection when moving from affected to unaffected animals, keep lambing pens empty for a period after abortion)
  • Highlight zoonotic risk of Toxoplasma and EAE to the farmer
29
Q

After an abortion storm in a flock, what steps should be taken in future to prevent this happening again? Specify which pathogens these steps take action against.

A
  • To protect against EAE - purchase accredited disease-free stock and keep separate until after first lambing
  • To protect against Toxo - prevent transmission via definitive host i.e. keep cats out of the feed stores
  • To prevent against both Toxo and EAE - vaccinate!
30
Q

How can antibiotics be used in EAE control? Which antibiotic would you choose?

A
  • Oxytetracycline
  • Oxytetracycline can help maintain the placenta in ewes infected with Chlamydophila abortus to try and allow lambs to be born alive
  • Must be given after 90 days (when the placenta starts to deteriorate) and before Day 126 (3 weeks before lambing)
  • This protocol should not be used routinely; once a fully implemented vaccine protocol is in place, antibiotics shouldn’t be required
31
Q

If antibiotics are to be used in a flock to try to promote lamb survival despite C. abortus infection, which antibiotic should be used and when?

A

Oxytetracycline, after 90 days but before Day 126

32
Q

If ewes 6-8 weeks from lambing (i.e. day 91-105) have been infected with C. abortus , what could be used aside from oxytetracycline to try to improve lamb survival?

A

Could give a dead/inactivated vaccine e.g. Inmeva
Inmeva is not recommended in the last month of gestation

33
Q

If a ewe is close to lambing (i.e. less than 3 weeks to go) but is surrounded by ewes infected with C. abortus , what concerns do you have? What could you do about these concerns?

A
  • This ewe will not abort if she is infected because she is <3 weeks to lambing
  • However, if she becomes infected, she might abort next year
  • Could give a live vaccine pre-tupping next year (this will reduce abortions but not completely prevent) or use oxytetracycline at Day 91-129 in next gestation
34
Q

Which vaccines (live, attenuated, or inactivated) are suitable for use in pregnant animals?

A

Inactivated

35
Q

What are health and safety concerns with the live attenuated EAE vaccine?

A
  • Live attenuated EAE vaccine should not be used by women of childbearing age/ immunocompromised individuals

FARM ANIMAL (53 decks)

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