Abortion Flashcards
Want is the maximum acceptable abortion rate on a farm?
5%
What are some causes of non-infectious abortion?
Nutrition - selenium deficiency, NEB
Hormone abnormalities
Aflatoxins
What abortive agent can cause abortion at any time during gestation?
BVD
Salmonella
Arcanobacter pyogenes
Mycobacterium tuberculosis
Which abortive agent only causes abortion in early pregnancy?
Trichomonas
What abortive agent only causes abortion in mid pregnancy?
Neospora
List some primary abortive agents
Brucella abortus BVD Leptospirosis borgspetersenii Neospora BHV 1 Parainfluenza 3 Bacillus lichenoformis
List some secondary abortive agents.
Gram + Arcanobacter pyogenes Listeria monocytogenes Staph aureus Beta haemolytic strep
Gram - E.coli Salmonella Dublin Salmonella typhimurium Fusobacterium necrophorum Histophilus somni Leptospira borgspetersenii Pseudomonas aeruginosa
Others: Mycoplasma bovigenitalium
What lesions will you find in a foetus infected with BHV1?
Centrilobular necrosis of the liver
Bronchitis and vasculitis
What lesions will you find in a foetus with BVD in utero infection?
Cerebellar hypoplasia
Cataract
Myocarditis
Pale liver
Hypoxia changes in foetus due to placentitis
Radio-opaque lines in the developing bones
What lesions will you find in a foetus with iodine deficiency?
Thyroid hyperplasia
Large thyroid weight compared to BWt
What lesions will you see in selenium and vitamin E deficiency?
Myocardial degeneration in foetus
Chorionitis
Evidence of secondary bacterial invasion
When does the foetus start to develop a T cell immune system?
90-120 days of gestation
What is a notifiable cause of abortion?
Brucella abortus
How can you monitor for brucellosis in a herd and what samples must you take in a suspected case?
Bulk milk test - monitoring
Dam blood + vaginal swab + milk sample in a suspected case
How can you control brucellosis?
AI
What is a major source of BHV1?
The Bulls
Virus lies latent and recrudescence at times of stress
How can you diagnose BHV1?
ELISA
Intra-vaginal or intra-nasal swabs for PCR
How can you prevent BHV1?
Vaccination
Ensure bull is not infected
What is the most common cause of bovine abortion the uk?
Neospora
How is neospora spread?
By dogs - oocytes can be shed in faeces
Transplacental transfer from cow to cow
When does neospora cause abortion?
4-6 months of gestation
Which group of animals are at the highest risk of abortion?
Congenitally infected heifers in their first gestation
What are the possible outcomes of neospora infection?
Abortion
Clinically normal Calf born carrying infection
Uninfected weak calf
How can you diagnose neospora infection?
Maternal serology
- test ping calf at birth can show dam infection
Brain histopathology on a dead Foetus
How can abortion patterns indicate the source of infection with neospora?
Abortion storm - exogenous infection (oocysts)
Endemic, low, chronic levels - endogenous infection (trans-placental)
How can you control neospora?
Keep dogs away from cattle feed and water
Don’t allow dogs to scavenge bovine carcasses
Cull seropositives
Breed to beef
Use sexed semen to get more heifers from uninfected animals
At what stage of pregnancy does foetal reabsorption occur with BVD?
0-95 days
1st trimester
At what stage of gestation is a persistently infected calf created if infected with BVD?
95-120 days
2nd trimester
Infection with BVD at what stage of gestation creates a sero-positive foetus +/- congenital lesions, or abortion due to placentitis?
120-285 days
3rd trimester
What BVD bio types cause what types of disease?
Pestivirus genotype 1 is the causative agent of BVD in Europe
Non-cytopathic biotype - crosses fetomaternal barrier
Cytopathic biotype - mucosal disease
What is the effect of BVD infection in the herd?
Lowered pregnancy rate due to reproductive system damage
Abortion
What effect does BVD have on the persistently infected calf?
Causes immunosuppression - risk of other disease
Poor doers
She’s virus
Get mucosal disease when infected with a cytopathic biotype
- ulcerations of the mucosa
- diarrhoea
- concurrent respiratory disease due to immunosuppression
What congenital abnormalities are commonly caused by BVD if infected between 120 and 285 days of gestation?
Cerebellar hypoplasia
Micropthalmia
Cataracts
How can you diagnose BVD in a herd?
Quarterly Bulk milk Ab - doesn’t detect PIs
Ear tag Ag testing - detects PIs (9-18wo)
5 blood tests bet group
- heparin tube for antigen
- serum tube for antibodies
How can you control BVD in a herd?
Vaccination before the first breeding
Test the bull - blood and semen
Test any bought in animals
Good biosecurity
Cull persistently infected animals (ear tag test)
Don’t co-graze with sheep - border disease risk
What are the two strains of leptospirosis that cause abortion in cattle?
Leptospira interrogans
Leptospira borgspetersenii
Not leptospira icterohaemorrhagiae - causes jaundice and renal failure
ZOONOTIC
What are the clinical presentation of leptospirosis?
Latent phase - no clinical signs
Persistent infection - infertility, shedding into environment
Acute infection - abortion, still birth, weak calves
Milk drop
Flabby bag! Empty and flaccid udders
Retained foetal membranes
How can you diagnose leptospirosis?
Bulk milk antibody testing - shows infection has been there
Microagglutination test on blood serum
Immunfluroescence / PCR on aborted tissues, blood or urine
= most diagnostic
How can you treat leptospirosis?
Long courses of antibiotics
Dihydrostreptomycin
Oxytetracycline / doxycycline
What control methods ca you employ to keep leptospirosis out?
Test or avoid bought in animals
Use AI instead of a bull
Do not do graze with sheep
Fence off water courses
Vaccinate all breeding stock and replacements from 4mo
- annual boosters
What is the most common cause of salmonella abortion in cattle?
Salmonella Dublin
Auto genius vaccines available
What is the seasonality of Salmomellosis?
Abortion in September to December
What are common sources of salmonella?
Soya
Feed and water contaminated by bird faeces
When should you vaccinate against salmonella Dublin?
2 months before calving
How else can you control salmonella Dublin?
Vaccinate Calve outside in the summer Good hygiene Treat and cases Reduce stress (increases shedding)
How does campylobacter foetus venereallis present?
Mild endometritis
Apparent infertility due to early embryonic loss (1st 3w)
Abortion in mid to late gestation (4m onwards)
How can you diagnose campylobacter foetus venereallis?
Preputial washing in Bulls
Vaginal mucus aspiration in cows for culture
How does abortion due to trichomonas foetus present?
Natural service spreads infection
Abortion at 2-4m of gestation
Poor pregnancy rates
Pyometra
Endometritis
What should you look for in a foetus post mortem in an abortion investigation?
Crown to rump length - indicated gestational age Thyroid gland weight Fractures / haemorrhages Pericarditis Pleuritic Peritonitis Placentitis Liver rupture - dystocia Meningeal haemorrhage / oedema
What samples should you take in an abortion investigation?
Placentome or placenta Spleen - BVD PCR Liver - IBR + bacteriology Stomach contents - salmonella + campylobacter Kidney - leptospirosis Brain - neospora Left ventricle Thyroid Eyelid - ureaplasma & fungal hyphae in hair follicles Paired dam serology
What causative agents of abortion can be tested for in a bulk milk sample?
BVD
Leptospirosis
IBR
Neospora antibody
BVD antigen PCR can be performed on bulk milk tank if there are less than 300 cows
What are the problems with bulk milk tank testing?
Dilution effect
Need time to develop antibodies
Can’t tell if it is current infection or historic
How can you diagnose campylobacter?
Preputial wash from bull
Use phosphate buffered warm saline
Prevent faecal and urine contamination of samples
Send to lab within 4-6 hours
Vaginal mucous collection
Collect a minimum of 12 samples from 12 females
What approach should you take to managing BVD?
Quarterly bulk milk screening for BVD,p IBR and lepto
If negative - continue as normal
If positive test 1st lactation heifers
Work your way down the different age groups of young stock
Pregnant heifers, bulling heifers, growing heifers
What would you suspect if the bulk tank is test positive for BVD antibodies but the 1st lactation heifers are BVD negative?
Historic infection
How are BVD herds classified using bulk milk tank testing?
Ab negative, Ag negative - BVD free
Ab positive, Ag negative - historic infection
Ab positive, Ag positive - current infection
What is the most obvious sign of IBR in a herd?
Milk drop
How can you treat campylobacter?
Systemic streptomycin
Sheath lavage with pen/strep
