Abortion in cattle
Non infectious causes
1. Toxic eg nitrates
2. Hereditary
o Protoporphyria
o Mannosidosis
3. Metabolic
o Iodine
o Vitamin A
4. Stress??
5. Iatrogenic
o Bad pregnancy testing
o Prostaglandins (PGF2)
 Are luteolytic – cause decrease in prog level & induce uterine
contraction.
 Also used to induce & synchronise oestrus, and retained
placenta.
o Corticosteroids eg Dexamethasone
 Can be used (25mg) for abortion with PGF2 after 150 days of
gestation
 May induce parturition when 20-30mg IM given within 2 wks of
normal term.
Infectious causes
1. Viral
o BHV-1
 aka Infectious bovine rhinotracheitis (IBR), red nose, bovine
herpes virus
 more Canada, USA
 Subtype 1.2a isolates cause abortions
 Worldwide occurrence – high prevalence & low incidence
 transx – nasal exudate/droplet – aerosol; genital secretions,
semen, foetal fluids & tissues – venereal
 Virus may survive up to 1 year in semen frozen at –196oC
 Virus may be transported by peripheral leukocytes to placenta
& transferred to foetus  abortion.
 Foetus highly susceptible – peracute infection, usually fatal
 Infection last trimester – mummification, abortion, stillbirth,
weak calves with IBR lesions + lesions of stomach & intestines
 Infection of newborn calves – severe inflammation & necrosis
of respiratory & alimentary tracts. Severe laryngeal oedema &
resp distress  aspn pneumonia
 Beef feedlot cattle can get severe, highly fatal syndrome 
diffuse erosion & ulceration of upper alimentary tract, inc oral
cavity.
 Vaccines made with 1.1 subtype are abortifacient & can cause
infertility in cattle infected 14 days after breeding
o
**** Pestivirus (BVDV, Mucosal disease) ****
 Occurs worldwide
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 Persistently infected (PI) calves are major source of virus. Noncytopathic types crosses placenta, invades foetus  PI
infection.
 Cytopathic type usually only assoc with mucosal disease in
those already PI.
 Transx – PI viraemic animal, virus can be isolated from nasal
discharge, saliva, semen, faeces, urine, tears, milk. Direct
contact and transplacental. Indirect – blood feeding flies,
fomites (same glove, reusing needles)
 Clinical findings –
 Non-clinical/mild disease – high morbidity. Mild fever
leukopaenia, inappetence, mild diarrhoea  rapid
recovery in few days. Develops Ab’s. Occurs in
immunocompetent seroneg.
 Peracute BVD – severe enteric form. Often fatal. Occurs
in immunocompetent seroneg. Severe depression,
Respiratory distress, anorexia, ++ watery diarrhoea,
dysentery, conjunctivitis, fever (to42 C), agalactia. +/late abortion, oral lesions.
 Acute mucosal disease – sudden onset animals 6-24/12
infected early foetal life. Low morbidity, high mort.
Animals in good condition may be affected. May be ed
no’s of PI animals post outbreak b/c spread of infection
& devp acquired immunity inbreeding females. Affected
animals – depressed, anorexic, drool saliva, wet hair
around mouth, fever, tachy, polypnoea, absent ruminal
contractions, ++ watery diarrhoea (offensive +/mucous, blood, fibrinous casts) 2-4 d post onset. Oral
lesions – discrete, shallow  confluent  necrotic
epithelium on lips, gums, dental pad, hard palate,
tongue, commissures of mouth & muzzle. Nasal d/c –
mucopurulent & lesions on nares, +/- lacrimation,
corneal oedema, lameness (due to laminitis, coronitis,
erosive lesions of interdigital cleft). Dehydration,
weakness & death 5-7d post onset of signs.
 Chronic mucosal disease – may survive up to 18m. CS
include diarrhoea, inappetence, emaciation, rough dry
hair coat, chronic bloat, hoof deformities, chronic oral &
skin erosions. Lesions also on perineum, between legs,
skin horn junction of dewclaw.
 Unthrifty PI calves – smaller, fail to grow normally. +/curly haired coat. Seroneg. High incidence of fatal
respiratory disease when 7-9m old.
 Repro failure & neonatal disease – infection at time of
insem & during embryonic-mid foetal period 
conception failure, embryonic mortality, mummification,
abortion, prem birth, stillbirth, cong defects, stunted &
weak calves, PI calves. Losses may occur 2-4y. Weak
claves generally born during first 2-4w of calving
season.
 Ag detection – immunofluorescence, ELISA, PCR
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 Serology – detect & measure Ab’s. Acute infection – Se Ab first
detectable 2-3 wks, peak Ab levels 8-10 wks later.
 Herd screening – serum samples all animals >3/12 & whole
blood from calves <3/12. Test all herd.
 Histo – formalin fixed oral/oesophageal lesions, thymus,
peyers, colon
 Mx – isolate young & breeding from infected. Cull
infected/chronic.
 Vaccinate pre breeding (vacc heifers 6/52 pre-breeding)
 Tx – nil specific. If ++watery diarrhoea – slaughter/euthanase
o
o
o
Akabane
 Infection of dam in early pregnancy with subsequent infection
of the foetus.
 Transx – Arbovirus, by haematophagous insects (Culicoides).
 Epidemic pattern – get outbreaks periodically (every 5-7 y).
Naïve animals susceptible, strong immunity once had it.
 Clinical findings – abortions, stillbirths, calves with skeletal
deformities (arthrogryposis – “curly calves”) & neurological
disorders (hydroencephalopathy).
 Dx – CS, maybe serology. Virus isolation not reliable.
 North Australia, C. brevitarsis active throughout yr so cattle
infected with virus before their first pregnancy.
Aino
 Cause of disease in Australia & Japan
 Transx – mosquitoes & midges
Polyam

2. Bacterial
o Salmonellosis spp.
 Usually endemic or sporadically when individual animals
exposed to stress
 Abortion most commonly due to S.dublin may occur
spontaneously without any clinical evidence of Salmonellosis in
the herd
 Abortion occurs day 124 – 270 d (second ½) of gestation
 Calves may be born preterm & die in perinatal period, sick &
weak
 Cows may have a fever, anorexia, hypogalactia +/- RFM
 Serology
 Dx – CS, histpoath, bacto culture, serology
 Prevention – vaccination, cull carriers, treat, hygiene
o
Campylobacter spp.
 Includes C. fetus var. veneralis, C. fetus subsp fetus,
 C. fetus fetus – sporadic abortion in cattle
 C. jejuni – abortion in beef cattle herds, occurred late gestation
with RFM and weight loss. Necrotising and suppurative
placentitis and foetal bronchopneumonia with large numbers of
C. jejuni cultured from placental & foetal tissues.
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 Transx – faecal contamination of water supplies & feeding
grounds by carrier cows or wildlife
o
Arcanobacter pyogenes
o
E. coli
o
Leptospira spp.
 L. pomona & L. hardjo
 L. hardjo is important cause of bovine abortion.
 Previously known as Actinomyces
 Ubiquitous organism – found in environment, intestinal tract,
+/- tonsils of healthy cattle
 Gains access thru contaminated abrasions or wounds, insect
bites, post partum (esp. if retained foetal membranes)
 Post partum infections often accompanied with G –ve
anaerobes Fusobacterium necrophorum and Bacteroides
melaninogenicus which act synergistically.
 Abortion at any stage of pregnancy. Causes < 5% of cattle
abortions.
 Dx – aborted foetus + placentome

 Seroprevalence surveys have found that 25-65% of all cows
tested were positive.
 Abortion mainly second ½ of pregnancy (last trimester).
 Transx – infected animal which contaminates pasture, drinking
water & feed by infective urine, aborted foetuses & uterine
discharges. Infected semen via natural breeding or AI.
Organisms can be shed in urine for up to 6m. Organism can
enter thru cutaneous or mucosal abrasions.
 Worse in wet winters - ? longer survival time org in water
 Dx – difficult. Maternal serology. Urine – spirochaetes (low
sensitivity)
 Control – vaccination with 7in1 has decreased incidence.?
Twice yearly for L.hardjo – rarely done.
 CS  Zoonotic – care with infected urine or uterine contents.
o
Brucella abortus (not Australia)
 Transx – from infected animal to susceptible via uterine
discharge.
 Congenital infection in newborns due to in utero infection
 Natural infection & vaccination  immunity to abortion but not
infection. Infected animals serologically +ve long time.
 Sexually mature animals susceptible. Outbreaks in first calf
heifers. Older cows infected but don’t abort.
 Signs – abortion epidemics in first calf unvaccinated heifers
after 5th month gestation. Subsequent pregnancies carried to
term.
 Bulls – orchitis & epididymitis  synovitis (hygromas)
 Dx – Serology. Serum agglutination is standard test.
Complement fixation test. ELISA test. False +ve major problem.
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 Lesions – necrotising placentitis & inflammatory changes in
foetus.
 UK – DEFRA requires all cattle farmers to report abortions &
prem calvings.
o
Listeria monocytogenes
 May be an associated septicaemia. Cows which abort may die
of septicaemia near term.
 Low abortion rate. Usually about 7 mths.
 Foetus – autolysis. Foci of necrosis in liver & other organs.
 Isolate agent from foetal stomach, placenta & uterine fluid.
 Serology – agglutinn titres > 1:400 in contact animals are +ve.
3. Bacterial
o Neospora caninum
 Major cause of abortion in Australia
 Worldwide, mainly dairy cattle. Sporadic outbreaks common.
>20% of Qld dairy cows infected
 1st service pregnancy probability ~ 20-30%
 ** Repeat abortions from same cow common
 Abort b/w 4-6 mths gestation
 Abortion most commonly – resorption, mummification,
stillbirths
 Transx – vertical & horizontal
 Dx – Histopath - Isolate parasites from foetal brain (best is
squashed preparation) & myocardium. Degenerative lesions
widespread in foetus. Non-suppurative necrotising encephalitis
& myocarditis common
 Antibodies in foetus & cow. IFAT & ELISA.
 Definitive host – dogs, +/- foxes, +/- cats
 Control – remove foetal membranes from dogs/cats (difficult)
Prevent access of cats & dogs to cattle feed
ET to preserve genetics in herd (embryos unlikely +ve)
Culling +ves
Vaccination – trial in NZ
o Sarcocystis

o Trichomonias
 CS – infertility. Return to heat at 4-5 mths, abortion (2 – 4
mths) & pyometra
 Placenta – flocculent material & clear serous fluid in uterine
exudate
 Foetal maceration & pyometra common

4. Fungal and rickettsial
o Aspergillus
 Abortion occurs 3 – 7 months
 Placenta – necrosis of maternal cotyledon, adherence of
necrotic material to chronic cotyledon causes soft, yellow
cushion like structure.
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o
o
o
 Foetus may have small, raised grey-buff soft lesions or diffuse
white areas on skin. Resemble ringworm.
 Isolate agent from cotyledon, foetal stomach for hyphae +
culture.
Chlamydia psittaci
 Major source of infection is the placenta & uterine discharge of
aborting animals. Organism shed for week before and 2 wks
after aborting.
 Common in sheep & may transmit to cattle on the same farm.
 Zoonoses – preganat women working with infected ewes have
become infected and aborted.
 Abortion occurs last trimester. Infected calves born alive may
show lethargy, depression & may be stunted.
 Necropsy – aborted foetuses – no gross abnormality. Placenta
should be examined.
Coxiella burnetti (Q fever)
 High seroprevalence in ruminants
 Latent infection with recrudescence & excretion at parturition.
 Transx – direct contact & inhalation. High [] organism in
placenta & foetal fluids. Also in urine (& sheep faeces). In
semen of sero+ve bulls  venereal transx.
 Very resistant to physical & chemical influences. Survives in env
& soil for months.
 Rare cause of abortion in cattle.
 Zoonotic via inhalation
 Necropsy – placentitis. Organisms in trophoblast cells by
fluorescent Ab
 Dx – serology ltd value. Fluorescent Ab staining & PCR
 Control – isolation of aborting ruminants for 3 wks. Burn
aborted & placental material. Raise feed areas so not
contaminated from urine/faeces. Vaccination.
Anaplasma marginale
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Vaccination
5 in 1
Clostridium perfringens type D
Cl. tetani
Cl. novyi Type B
Cl. septicum
Cl. chauvoei
tetanus
Enterotoxaemia (pulpy kidney disease)
Black disease (occurs as sequel to liver fluke infestation)
Malignant oedema
Black leg (sheep & cattle)
Swelled head (rams)
6 in 1
7 in 1
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