Bovine abortion: Causes Flashcards

1
Q

What is the definition of abortion?

A

An abortion is the expulsion before full term of a conceptus incapable of independent life, while a premature delivery is the expulsion before full term of a fetus capable of independent life

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What should be done with cattle abortions?

A
  • Must be reported
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why is abortion a problem?

A
  • Reduced milk production - peak lactation
  • Poor reproductive performance - more days open, increased RFMs, reduced conception
  • Lower maternal survival - mortality / cull
  • Many abortion agents are zoonotic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the basic cost of abortion?

A
  • Dairy = no calf, loss of milk + Tx (+cost of replacement animal)
  • Beef = loss of calf + cost of keeping unproductive cow
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How do infectious agents cause abortion?

A
  • Primary abortion agents: cross the feto-maternal barrier e.g. Brucella abortus
  • Opportunistic pathogens: cross pre-damaged barrier e.g. Salmonella
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What non-infectious agents can cause abortion?

A
  • Nutritional
    -Nutrient deficiency e.g. selenium, iodine, vit A
    -Energy deficiency
  • Developmental-hormones, CVM
  • Toxins-aflatoxins, nitrite/nitrate
  • Trauma, Insemination, Hyperthermia, Twinning
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Whats the difference between primary and secondary abortifacients?

A
  • A primary abortion pathogen can cross the fetomaternal barrier itself e.g. Brucella
  • A secondary pathogen needs another agent to create damage so it can cross the fetomaternal barrier e.g. Salmonella
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are examples of primary infectious abortifaceints?

A
  • Brucella abortus
  • BVDv
  • Leptospirosis hardjo
  • Neospora
  • BHV-1 - IBR
  • Parainfluenza 3
  • Bacillus licheniformis
  • Fungi
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What happens monthly with dairy farms?

A
  • Bulk milk sampling for brucellosis and other diseases
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How do secondary pathogens cause abortion?

A
  • Usually associated with chorionitis /amnionitis
  • Placental steroidogenesis abolished (progesterone)
  • Associated inflammatory cascade and prostaglandins cause:
  • luteolysis
  • relaxation of cervix
  • fetus expelled
    e.g = LPS from E.coli
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the most important secondary abortion pathogens?

A
  • Listeria monocytogenes
  • Leptospira borgpetersenii
  • Salmonella dublin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the different routes of infection?

A
  • Resident flora of reproductive tract during pregnancy (ascending) - Streptococcus equi in mares
  • At time of service in cattle e.g. Ureaplasma diversum
  • Transplacental
  • Bacillus licheniformis in cattle; Chlamydophila abortus in ewes
  • Haematogenous – systemic infection
  • viruses e.g. pestivirus (BVDv); bovine herpesvirus-1
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are consequences to the foetus if exposed to pathogen?

A
  • Reabsorption
  • Maceration
  • Autolysis
  • Mummification
  • Abortion
  • Emphysematous
  • Born alive with congenital defects
  • Born alive but weak
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are foetal target tissues of abortion pathogens?

A
  • Chorio-allantois
  • Amnion
  • Bone = radiopaque lines
  • Soft tissues e.g. lungs
  • Endocrine glands e.g. adrenal
  • Immune cells of foetus
  • Specific cell types associated with organogenesis e.g.
    neuroglial cells = cerebellar hypoplasia (BVD)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How long into gestation does T cell recognition occur?

A
  • 90-120days into gestation (T cell recognition of self)
    Antibody production against:
  • BVD after 140d
  • Salmonella dublin after 165d
  • fungi after 200d
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

When do different pathogens cause abortion?

A
  • Campylobacter = 4-8 months
  • Trichomonas = 2-4 months
  • Mycotic, lepto, listeria = 4-9 months
  • IBR / IPV, bacillus, chlamydia = 5-9 months
  • Brucella = 6-8 months
  • Neospora = 4-6 months
  • BVD, salmonella, A. pyogenes + TB = throughout pregnancy
17
Q

What is seen with IBR?

A
  • Herpes virus
  • Unusual to have resp + repro symptoms
  • Look for IPPV, abortions, milk drop
  • Latent carriers
18
Q

What is seen with Neospora?

A
  • Most commonly diagnosed cause of abortion
  • 12.5% UK abortions; usually 4-6 months gestation
  • May cause early embryonic death which manifests clinically as infertility – rare
  • Congenitally infected heifers most at risk of abortion in first gestation
  • Cows infected by oocyst ingestion (exogenous)
  • Abortion OR persistently infected calf born
  • Recrudescence of infection in the cow = transplacental (endogenous)
  • Abortion OR persistently infected calf born
  • Outcome of infection: 10% abort; 80% PI; 10% normal / weak
19
Q

How can you control neospora?

A
  • Keep dogs away from cattle feed + water + dont allow to eat placentas
  • Breed +ve to beef do not keep + sell as replacement heifers
  • Use sexed semen to get more heifers from uninfected animals
20
Q

What are consequences of BVD?

A
  • Lowered pregnancy rates –
  • Epithelia lining reproductive tract and follicle infected
  • Only during viraemic stage
  • Abortion –
  • BVDv compromises foeto-maternal barrier allowing secondary bacterial infection (placentitis and foetal pathology) -> foetal death and abortion
  • PI calves
  • Congenital abnormalities
  • Mucosal disease
21
Q

How would you control BVD?

A
  • Test + biosecurity
  • Avoid co-grazing
  • Vaccinate
22
Q

What does Campylobacter fetus veneralis + fetus fetus cause?

A
  • Mild endometritis
  • Infertility due to early embryonic loss
  • Venereally spread