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Infectious Causes Impacting
Reproduction
Fetal Mummification
Fetus dies, uterus contracts, and fluid is resorbed  fetus
becomes dry/firm
–Thickened uterus
–CL present on ovary
–No palpable cotyledons
–No membrane slip
–No fremitus in uterine artery
–Palpable mass in uterus
Fetal Mummification
• Most common at 4-6 months of gestation, but may go beyond
gestation length
– Genetic (uncommon) – Jerseys, Guernseys, certain Holstein
families
– Torsion of umbilical cord
– Infectious diseases that cause minimal inflammation:
• Campylobacter fetus
• BVDV
• Tx:
– PGF2a IM to lyse CL and expel fetus in 2-3 days
+/- 2nd dose in 96 hrs if needed
– Manually remove with lube
– C-section
Fetal Maceration
• Fetal death with partial cervical dilation  uterine
contamination  bacterial growth (great medium!)
• Any age of gestation
• CS: abdominal straining, foul fetid vulvar discharge, fever,
anorexia, milk production +/- diarrhea
• Rectal: distended swollen uterus, gas crepetation in fetus
• Prognosis for future reproduction POOR - treatment not
always successful, endometrial damage extensive
• Tx:
– Cervix dilated: fetus removed manually with LUBE and
SLOW manipulation. Re-examine for 2nd fetus!
– Cervix closed: PGF2a +/- oxytocin (less successful than
with mummies; may not be functional CL)
Abortion
• Severe maternal illness:
– Infectious diseases: high fever, inflammation (mastitis,
pneumonia, virus…)
– Toxins: plants and chemicals (nitrates, moldy sweet
clovers, fescue molds, lupines, gossypol in cottonseeds,
and industrial pollutants…)
– Hypoxia (anemia, pneumonia…)
– Endotoxemia
• Placentitis:
– Hematogenous
– Ascending via cervix
• Fetal origin:
– Fetal stress → death
Abortion
• Mechanism:
– P4 and PGF2a  luteolysis + expulsion of
fetus
Abortion
• Due to the degree of autolysis and edema of
fetuses in utero after death but before
expulsion, gross placental/fetal lesions are
not usually diagnostically significant.
Abortion
• What tissues samples shall I send off ?
– Fetal membranes/aborted fetus – BEST!
– Fetal lung, liver, intestines, brain, kidneys…
– Maternal serum, urine, vaginal discharge…
• FRESH, keep cool
• Better too many than too few samples…
Abortion
Infectious Causes: *Especially if abortion storm!
• Bacterial
• Protozoal
– Brucella spp
– Trichomonas
– Listeriosis
– Neospora
– Leptospirosis
• Viral
– Arcanobacterium pyogenes
– IBR
– Vibriosis
– BVD
• Mycotic
Brucellosis
“Contagious abortion”, “Bangs disease”
• Brucella abortus
• ZOONOTIC – Undulent fever in humans (via milk)
• Eradication program  ~rare in US herds, but still in
free-ranging bison/elk
• Highly infectious – spread via aborted fetus, placenta,
vaginal discharge, milk, or semen from infected bull
• Lesions – chorionic placentitis,
Moroccan leather appearance,
focal necrosis of cotyledons,
thickened intercotyledonary
areas with yellow exudate
Brucellosis
• Abortion usually between 5th-8th month of gestation
– Also frequently causes retained placenta, weak calves and
infertility
• Dx: serology/culture of fetal abomasal fluid, lung, and
liver, placenta, uterine fluid, milk, serum, seminal
plasma
• Prevention/Control: Official calfhood vaccination
– RB-51 vaccine (“bangs” vaccine) + Official USDA
Brucellosis eartag + official ear tattoo
– Calves 4-10 months of age
– By state and federal brucellosis program personnel and
USDA accredited veterinarians
Listeriosis
• “Circling Disease”
• Listeria Monocytogenes
• ZOONOTIC
• Widespread in environment; transmission via ingestion
of poorly fermented silage
• Fever, weight loss, endometritis, encephalitis
• Lesions: suppurative placentitis,
small white foci on fetal liver
and cotyledons, fibrin in fetal body cavity
Listeriosis
• Abortion usually during 3rd trimester
– Sporadic or abortion storm
– Retained fetal membranes
• Control: stop feeding spoiled material, isolate
aborting cows
– Broad Spectrum Antibiotics  milk withdrawal
due to milk residues!
– NO vaccine in US
Leptospirosis
• Leptospira interrogans serovars hardjo & pomona
• Transmission via infected urine, placental fluids,
milk, or contaminated environment/water source
• Abortion from 4 months to term
• +/- yellow MM, blood tinged urine and milk
– Weak calves or infertility is also common
• Dx: Culture - organisms in fetal kidney
• Tx: Vaccinate annually
Arcanobacterium pyogenes
• Abortion at any stage of pregnancy
• Normal inhabitant in nasopharynx of many cows, also
in abscesses, NOT in fetuses or fetal membranes =
always significant!
• Bloodstream  endometritis & placentitis (diffuse
with a reddish brown to brown color)
• Fetus: autolyzed, with fibrinous pericarditis, pleuritis,
or peritonitis possible, as well as bronchopneumonia
• Dx: culture from placenta or abomasal contents
• NO effective bacterin available
Arcanobacterium pyogenes
• *Important cause of pyometra post-calving
in DAIRY cows!
– Diagnosed at pre-breeding check (~ 40 d post
calving)
– Occurs when cow ovulates in face of A. pyogenes
in uterus  pyometra
• Usually uterine contaminates are expelled from uterus
during normal involution process
• Pre-disposing factors: dystocia, RFM, metritis
Vibriosis
• Campylobacter fetus subsp venerealis
• Bulls are asymptomatic carriers, permanent carries when > 4
yrs
• Venereal transmission  organism attacks conceptus  early
embryonic death (occasional abortions ~ 4-7 months of
gestation)
• Cows develop immunity and conceive, and maintain the disease
in the herd (carriers)
• Dx: Blood agar culture of preputial smegma, fetal abomasal
contents, vaginal/cervical mucous
• Tx: ID and cull carriers, topical antibiotic ointment
• Control/Prevention: AI, prevent re-infection, blood culture all
non-virgin bulls 6-8 weeks before breeding season,
VACCINATE cows and bulls
Trichomoniasis
• Trichomonas foetus
• Bulls are asymptomatic permanent carriers
• Venereal transmission  organism attacks conceptus
• Cows develop immunity and conceive (carriers)
• *Important cause of pyometra post-breeding in
BEEF cows
• CS: infertility, pyometra, abortion
• Dx: microscopic isolation of organism (preputial
smegma or vaginal/cervical mucous) with Diamond’s
medium (Klaas modification)
• Control/Prevention: AI, use of virgin bulls
– NO vaccine available
Neospora
• Neospora caninum
• Cycles between canids and ruminants – oral
or vertical transmission
• Mid-gestation abortion (~4-6 months), premature calf, birth of impaired calf, or normal
calf
• Brain hemorrhage, myocarditis
Oocysts ingested while grazing
 Sporozoites released, enter SI  reticulo-endothelial system
Tachyzoites = invade different tissues, placenta  fetus in pregnant animals
Bradyzoites = dormant, within tissue cysts (found mainly in neural tissue)
•In future pregnancies, bradyzoites  tachyzoites  invade the fetus via the placenta
Infectious Bovine Rhinotracheitis (IBR)
• Acute, contagious Bovine Herpes Virus
• Infertility, respiratory infections, conjunctivitis,
abortion storm usually > 5 months gestation
• RFM, placental edema/vasculitis
• Fetus: red serous body fluid, white foci on
liver/lungs
• Tx: Vaccinate annually
“red nose”
Infectious Pustular Vulvovaginitis
• Also a Bovine Herpes Virus
• Venereal/mechanical spread
• Genital pustules (balanoposthitis)
• Spontaneous recovery
Bovine Viral Diarrhea Virus
(BVD)
• Affects the digestive, respiratory, immune, nervous
and reproductive systems
• BVD Type I and Type II, each with:
– Cytopathic (CPE) strains  cellular vacuolation
and cell death
– Non-cytopathic (non-CPE) strains  no visible
cytopathic change in cell cultures
Bovine Viral Diarrhea Virus
(BVD)
• BVD infection in-utero:
– Slows fetal growth  lower birth weight, bone
growth
– Abortion (at any trimester)
– Early embryonic death
– Stillbirth
cerebellar hypoplasia
– Congenital Birth Defects (eye, thymus, brain)
– Arthrogryposis
– PI Calves (immunotolerant and persistently infected
shedders)
– Normal calf born with antibodies to the BVD virus
Bovine Viral Diarrhea Virus (BVD)
Results of fetal infection with BVDV
Outcome
Gestational age at time of in utero infection.
0 - 40 days
40 - 125
125 - 180
> 180 days
Normal, antibody negative calf
X
X
X
X
Abortion
X
X
X
X
Early embryonic death, resorption
X
Mummification
X
X
Stillbirth
X
X
Congenital defects, antibody negative
X
Congenital defects, antibody positive
Persistently infected, "normal" calf
Normal, antibody positive calf
X
X
X
+/+/-
http://www.livestocktrail.uiuc.edu/dairynet/paperDisplay.cfm?ContentID=220
X
Bovine Viral Diarrhea Virus (BVD)
• Mucusal disease:
– PI calf (infected in-utero from 42-125 d of
gestation with non-CPE strain, seem normal, but
have no immunity to the virus)
– + encounters CPE strain after birth
(vulnerable to severe effects of the CPE cellkilling strain)
– ~6 months – 2 yrs old
– High mortality
Bovine Viral Diarrhea Virus (BVD)
• BVD infection after birth:
– Usually 6 months to 2 yrs of age
– CS: vary depending on the virulence of the strain
– Viremic  develop antibodies  clear virus within 710 days
– Subclinical (estimated 70-90% of BVDV infections)
• Mild elevation in body temp, drop in milk production
– Clinical = Acute BVD
• Depression, fever, inappetence, nasal discharge,
transient leukopenia, thrombocytopenia, petechial
hemorrhages, diarrhea, high morbidity, low mortality
• Eliminate Carriers = CULL!
• VACCINATE before breeding
Mycotic Abortion
• Aspergillus, Absidia, Mucor, Rhizopus, Candida
• More in WINTER when cattle housed/fed inside
• Injury to respiratory/GIT  hematogenous 
uterus  severe necrotic placentitis
– Thick, leathery cotyledons + intercotyledonary
placenta
• Abortions in 3rd trimester
• Head and neck lesions on fetus
“Given the low diagnostic success rate, the
high cost of laboratory work, and the low
profit margin in both the beef and dairy
industries, veterinarians should not attempt to
make an etiologic diagnosis in every
abortion. Instead, veterinarians should
become concerned if fetal loss is >3-5% per
year or per month.”
~ The Merck Veterinary Manual