Bovine Abortion: Investigation and control methods

How do you work out abortion incidence?

aborted / 100 calved

What questions do you ask regarding direct transmission within the herd?

• Are sick cattle isolated?

• Is the bull tested? (pre-putial wash and bloods)

What questions do you ask regarding BVD within the herd?

• are new females from not certified free herd tested/ are their calves tested?

• are bulls from not certified free herd tested?

• are non brreding cattle from not certified free herd tested?

What questions do you ask regarding youngstock within the herd?

• do you rear offspring from your breeding cattle such that could be in contact with adult breeding females?

• any youngstock of unknown dz status have contact with adult breeding females?

• youngstock screened for active infec (include PI) before in contact with adult breeding females?

Why is vaccine complience important?

• Half vaccines 1^o course given at incorrect interval.

• Only 24% given vaccine at correct time relative to service

• 20% given wrong dose/route

• kept longer than recommended

What do you do when you PM a calf?

• crown-rump length ref gestational age

• thyroid gland size/weight

• fractures/haemorrhages (ribcage + sternum, chest compression + epicardial bleed, liver rupture, skeletal trauma)

• fluid compartment –itis (inflam lesions - conjunctivitis, pericarditis, pleuritis, oedema in lungs)

  • culture (foetal stomach contents —> reflect what was in amniotic fluid)

• placentitis

• liver rupture

• meningeal haemorrhage / oedema

• developmental abnorm of GIT or other abdo ST

What different samples should you take and what do the labs look for in the different ones?

• Placentome or placenta

• Spleen -> bvd pcr

• Liver -> IBR + bacteriology

• Stomach contents -> bacti e.g. Salm; campy

• Kidney -> lepto

• Brain -> Neospora

• Left ventricle (myocardial exam, Se/vit E)

• Thyroid

• Eyelid -> ureaplasma; fungal hyphae in hair follicles

• Paired dam serology

What fastidious pathogens may the lab not be able to ID?

• Chlamydophila abortus

• Leptospira interrogans

• Anaplasma phagocytophilum

• Coxiella burnetii

• Listeria monocytogenes

• Caompy fetus

What should the thyroid weight in g be?

foetal weight(kg)/ 2 to 3

How can foetal age be determined?

CRL = crown rump length

What do bulk milk samples test for?

What are they useful for?

• BVD/Lepto/IBR/Neo antibody

• Useful for changing trends in the herd

• More useful if negative

• Antibody following natural infection is long lasting for BVD, BHV1 and L Hardjo.

• Antibody levels following inactivated vaccination can be low and short lived for BVD and BHV1

What are the other BVD diagnostics that can be used?

• Seroconvert over three weeks

• Detect PI in blood from one month of age (< 30 days MDA interferes) - or before colostrum

• Ear notch tissue test when tagged

• Check test (five bloods per group)

• Bulk tank PCR detection limit one in 300

• Probably 50% dairy herds are bulk tank BVD Ab +

Describe the preputial washing of bulls for diagnosis of campylobacter?

• Phosphate buffered saline warmed

• Prevent faecal contamination

• Discard urine contaminated samples

• Delivery to laboratory within 4-6 hours of collection

• Low sensitivity

How do you treat campylobacter?

• Systemic: Streptomycin 10mg/kg

• Sheath lavage: 100 mls pen/strep

How do you test females for campylobacter?

• Select 12 females most recently identified as problem —> Vaginal mucus collection

• Detects IgA

• From 7 weeks to 10 months PI

  • only 50% infected females prod +ve response

  • 50% of +ves become -ve within 6 months

What can you do in an outbreak of Infectious bovine rhinotracheitis (BVH-1)?

look for IPPV; look for symptoms in the bull; Abortions; Milk drop (herd)

Latent carriers (Trigeminal ganglion) —> Recrudescence (stress)

dx—> Serology – ELISA, Swabs – Immunofluorescence

• Vaccines

  • Intra-nasal

  • Marker vaccine

What is the best way to diagnose neospora?

PM (brain histopath of dead foetus)

can also Maternal serology, lowest antibodies at 12-18 m/o

increasing Ab levels as evidence of recrudescence

Test calf at birth ; indicates dam infected if calf is +ve

How do you diagnose lepto?

• Bulk milk antibody testing gauges level of infection in herd

• Serology by MAT

• Identification of leptospires from aborted tissue, blood or urine by IF or PCR

How do you treat/control lepto?

• Antibiotics – prolonged course of dihydrostreptomycin or oxytetracyclines

• early tx help prog. in prevent latent infec

• Vaccination (~4 months of age, repeat annually))

What is the timeline for getting BVD herd accreditation?

In which of these test results would you want to look for a PI animal for BVD?

• Left

• If +ve : next step : composite first lactation heifers

• Bleed groups of youngstock for antibodies

• For BVD use bulk tank PCR for antigen

antibody -ve + antigen +ve = PI animal

What should be done if bulk tank Ab +ve for L Hardjo?

zoonotic

vaccinate

What should be done if bulk tank Ab +ve for IBR?

not zoonotic but production losses

vaccinate

What are the different situations in which biosecurity should be considered?

• Added animals

  • Young calves

  • Pregnant females

  • Bulls

• Management of quarantine

• Management of breeding animals at grass

• Management of show and sale animals

• Visitors and equipment