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Y4 FA - Reproduction > Bovine Abortion: Causes > Flashcards

Bovine Abortion: Causes Flashcards

1
Q

Define abortion

A

Calving that occurs less than 270d gestation

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2
Q

What needs to be done when cattle abort?

A
  • Must be reported
  • May need statutory testing for Brucellosis (we are currently free of this)
  • May need investigation
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3
Q

What are the problems caused by abortion

A
  • Decreased reproductive performance
  • Increased change of failing to conceive again
  • Reduced milk production
  • Lower maternal survival: mortality/cull
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4
Q

What are the cost implications of abortion in dairy herds

A
  • No calf + lost milk +treatment
  • Do you rebreed the cow?
  • OR cost of replacement animal £1500-2000 (more than the culled cow)
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5
Q

What are the cost implications of abortion in beef herds?

A

Loss of calf + cost keeping unproductive cow

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6
Q

Describe the features/important of Brucellosis

A

Notifiable
Zoonosis
In the UK all abortions must be reported
Monthly routine bulk milk sampling

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7
Q

Describe stat testing for Brucellosis

A

Dams blood + vaginal swab + milk (if milking)

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8
Q

What % of bovine abortion is due to infectious disease?

A

40%

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9
Q

Why is it important to try and diagnose the reason for abortion?

A
  • Economically important
  • Vaccination
  • Zoonotic infections
  • Venereal infections
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10
Q

How do primary abortive agents cause abortion?

A

Cross the feto-maternal barrier e.g. Brucella abortus

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11
Q

How do opportunistic pathogens cause abortion?

A

Cross pre-damaged barrier e.g. Salmonella

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12
Q

List some non-infectious cases of abortion

A
  • Nutritional: may get calves born alive that are very weak - selenium, iodine, vit A
  • Developmental abnormalities
  • Toxins: aflatoxins, nitrite/nitrate
  • Trauma, Insemination, Hyperthermia, Twinning
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13
Q

List the target tissues for abortive agents

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)
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14
Q

What are primary abortive agents?

A
  • Destroy the integrity of the feto-maternal unit e.g. placentitis due to hypoxia
  • May/may not cause abortion
  • Allows opportunistic pathogens to invade placenta and fetus
  • Alters the microbiological profile within the pregnant uterus
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15
Q

List the primary abortive agents of cattle

A
  • Brucella abortus
  • BVDv
  • Leptospirosis
  • Neospora
  • BHV-1
  • Parainfluenza virus 3
  • Bacillus licheniformis
  • Fungi
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16
Q

Secondary opportunistic pathogens cause an inflammatory cascade and prostaglandin release. What are the consequences of this?

A
  • Luteolysis
  • Relaxation of cervix
  • Fetus expelled
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17
Q

Name the secondary opportunistic pathogens of cattle

A
  • Truperella pyogenes
  • Listeria monocytogenes
  • Staphylococcus aureus
  • E.coli
  • Fusobacterium necrophorum
  • Leptospira
  • Salmonella
  • Pseudomonas
  • Mycoplasma
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18
Q

Describe the 3 routes of infection of abortive agents

A
  • Resident flora of the reproductive tract during pregnancy
  • Transplacental
  • Haematogenous
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19
Q

Name 2 agents that cause abortion at any month in gestation

A

BVDv
Salmonella

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20
Q

Infectious bovine Rhinotracheitis is what kind of virus?

A

Herpes virus
BHV-1

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21
Q

What are the signs of Infectious bovine Rhinotracheitis?

A
  • Pustular vaginitis
  • Abortions
  • Milk drop
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22
Q

What is the most commonly diagnosed cause of abortion in cattle?

A

Neospora

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23
Q

When does abortion with neospora most commonly occur?

A
  • Congenitally infected heifers most at risk of abortion in first gestation
  • Cows infected by oocyst ingestion (exogenous) – life cycle through a canine -> Abortion OR persistently infected calf born
  • Recrudescence of infection in the cow: transplacental (endogenous) -> Abortion OR persistently infected calf born
24
Q

What are the %s of different outcomes with Neospora infection?

A

10% abort
80% PI
10% normal / weak

25
Q

Describe the two types of neospora infection in dogs

A
  1. Bradyzoite ingestion -> no disease -> variable antibody response -> oocysts in faeces
  2. Transplacental -> pup = intermediate host - Ab response -> disease
26
Q

How is neospora diagnosed?

A
  • Maternal serology
  • Testing calves at birth
  • Brain histopathology of dead foetus
27
Q

How can neospora be controlled?

A
  • Keep dogs away from cattle feed and water and don’t allow to eat placentas
  • Culling seropositive animals and offspring
  • Breed to beef and do not keep or sell as replacement heifers.
  • Use sexed semen to get more heifers from uninfected animals.
28
Q

How does the time of infection with bovine viral diarrhoea link with the likley outcome?

A

Day 0-95 = foetal reabsorption or abortion
Day 95-120 = PI status
Day 120-285 = Seropositive foetus +/- congenital lesions. Abortions can occur due to placentitis

29
Q

Describe the fertility 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

30
Q

Describe the consequences of BVD on calves

A

Persistently infected calves
Congenital abnormalities

31
Q

What is a persistently infected calf?

A

Antibody negative & antigen positive (serum for antibody, heparin for antigen)
Infection 95-120 days gestation

32
Q

When can you test for PI calves? Why?

A

Once a calf has had colostrum, even if it is virus positive, it may not show up on a blood test. So will have to wait 30 days to test if they’ve had colostrum

33
Q

What congenital abnormalities may be seen with BVD?

A

Cerebellar hypoplasia
Microphthalmia and cataracts

34
Q

PI calves with BVD are susceptible to which other disease in adulthood?

A

Mucosal disease

35
Q

Describe the aetiology of mucosal disease

A
  • PI animals infected then with cytopathic biotype
  • They are susceptible to mucosal disease (MD) if they “encounter” secondary infection with cytopathic virus as they do not mount an immune response. This is usually via mutation of the resident non-cytopathic strain to cytopathic
36
Q

Describe the clinical signs of mucosal disease

A
  • Ulcerations of mucosae (particularly tongue, soft palate, gingiva & oesophagus)
  • Ill thrift
  • Diarrhoea
    +/- Concurrent respiratory disease (immune suppression)
37
Q

How is BVD/mucosal disease diagnosed?

A
  • Bulk milk antibodies (quarterly)
  • Detect PI in blood from one month of age (< 30 days MDA interferes)
  • Ear notch tissue test
  • Check test: antibodies (five bloods per group) – if then +ve further testing needed
38
Q

How is BVD/mucosal disease controlled?

A
  • Test the bull (blood and semen)
  • Test bought- in animals
  • Good biosecurity (faecal contamination of fomites = risk)
  • Eradicate by testing and removal of PI’s +/- vaccination depending on level of infection and attitude to biosecurity and risk
  • Sheep : avoid co-grazing
  • Vaccination protects the pregnancy; before first breeding
39
Q

Why is leptospirosis important to diagnose?

A

Zoonotic

40
Q

How is leptospirosis spread?

A
  • Bacteria can reside in kidneys
  • Excreted for months to years, usually via urine
  • Spread by contact with skin, mucous membranes or orally
41
Q

Why must you not confused L. icterohaemorrhagiae with L.interrogans serovar and L.borgpetersensii?

A

L. icterohaemorrhagiae - causes jaundice and renal failure with the source being rats

42
Q

What are the clinical signs of Leptospirosis in cattle?

A
  • Often unapparent and cow in latent state
  • Persistent infection of reproductive tract (bull and cow) can result in infertility and shedding in discharges
  • Abortions, stillbirths and weak calves in acute infection
  • Retained foetal membranes
  • Milk drop (flabby bag) = uncommon
43
Q

How is leptospirosis diagnosed?

A
  • Bulk milk antibody testing gauges level of infection in herd
  • Serology by MAT (some debate as to what is a significant titre)
  • Identification of leptospires from aborted tissue, blood or urine by IF or PCR
44
Q

How are clinical cases of leptospirosis treated?

A

Antibiotics – prolonged course of dihydrostreptomycin or oxytetracycline – category C antimicrobial
- Early treatment aids prognosis in preventing latent carrier status (can be over a year)

45
Q

What are the risk factors for leptospirosis?

A
  • Buying in stock
  • Natural service
  • Co-grazing with sheep
  • Watercourses
46
Q

Is there a vaccination for leptospirosis?

A

Yes

47
Q

Which spp of salmonella is the most common serovar associated with bovine abortion?

A

S.dublin - zoonotic

48
Q

What are the sources of salmonella?

A

Faeces
Feed
Fomites

49
Q

What increases shedding of Salmonella?

A

Stress

50
Q

What is key for Salmonella control?

A

Hygiene

51
Q

How does Campylobacter affect fertility?

A
  • Causes mild endometritis
  • Likely infertility is due to early embryonic loss within 3 weeks of conception
52
Q

Which spp of Campylobacter causes abortion?

A

C. fetus fetus

53
Q

How is campylobacter spread?

A

Venereally

54
Q

Where is trichomonas fetus located in the body?

A

Confined to reproductive tract of cow and bull

55
Q

How is Trichomonas spread?

A

By natural service
- now less common due to AI

56
Q

What are the clinical signs of Trichomonas fetus infection?

A
  • Occasionally causes abortion
  • More commonly causes poor pregnancy rates
  • Pyometra and endometritis

Y4 FA - Reproduction (10 decks)

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