Bovine Abortions Flashcards
What cows should you assess first in abortion storm work-ups?
Those who have aborted most recently
What should you always submit to the lab when working up abortion cases when available? What should you always collect from moms?
Fetus and placenta
Blood
What does campylobacteriosis usually result in?
Infertility
What strains of campylobacter are more likely to cause sporadic late term abortions in cattle and small ruminants?
Campylobacter fetus ssp fetus and C jejuni
How is campylobacter spread from cow to cow?
Feco-oral
When does the majority of pregnancy loss occur with campylobacteriosis infections?
30-70 days gestation
What is the pathogenesis of how campylobacteriosis leads to abortion?
A heat stable endotoxin is produced with leads to placentitis. Swelling of placenta then leads to fetal hypoxia
How long does it take for infected cows to develop immunity against campylobacteriosis?
4-8 months
How do you diagnose campylobacteriosis?
rtPCR or IHC
What can mollicute (mycoplasma/ureaplasa) cause in pregnant animals?
Embryonic death, abortion, stillbirth, weak calves, neonatal pneumonia- AKA abortion can occur anytime!
How do you diagnose mollicute infections?
PCR of vaginal/preputial swabs, abortion-culture/PCR from fetal tissues
What type of antimicrobial is most effective against mollicutes?
Macrolides
What type of virus is BVD?
RNA, pestivirus, flaviviridae
Where is the site of inoculation of BVD infections?
Tonsils and Respiratory tract- then disseminates to other epithelial/lymphoid tissue. Can result in transplacental infections
What occurs when cows are affected at breeding with BVD?
Decreased conception rate due to embryonic loss
-etiology: oophoritis, salpingitis, hormone alteration
During what time frame during pregnancy can infection with BVD lead to persistent infection in fetus?
40-125 days!
What occurs if cows are affected between 100-150 days in pregnancy with BVD?
Congenital malformations-organogenesis, cerebellar hypoplasia, hydrancephaly, hydrocephalus, porencephaly, ocular changes
What occurs if infection with BVD occurs >125 days into pregnancy?
Abortions rarely, usually clinically normal calf with high levels of precolostral antibodies
How can you control BVD infections?
ID and remove PI animals, enhance immunity through vaccination (MLV before pregnancy ideal), biosecurity to prevent exposure
What type of virus is bluetongue and how is it transmitted?
orbivirus transmitted by culicoides varripennis
Describe the pathogenesis of bluetongue virus
After inoculation it replicates in the lymph nodes. Through hematogenous spread it then can lead to cell damage and thrombosis
- it can cause prolonged viremia (several weeks) but not persistent infections
What occurs if cow infected <70 days gestation with bluetonge? 70-130 days? >150 days?
<70: fetal death/absorption
70-130: stillbirth, weak calves, hydrancephaly, abortion
>150 days: premature birth +/- encephalitis
Which is detectable to diagnose bluetonge: virus or antibody?
Antibody
Is there a bluetongue vaccine?
Yes, but not labelled for cattle in US
What causes infectious bovine rhinotracheitis?
Bovine herpesvirus type 1 (double stranded DNA virus)
What are the different clinical manifestations of IBR?
- Mild to severe respiratory disease
- Ocular, neonatal, GI or neuro disease
- Genital symptoms
- Abortions
What are the sources of infections for IBR?
Nasal exudate, cough droplets, preputial secretions, semen, fetal fluids/tissue
Describe the pathogenesis of abortion due to IBR in non-immune cows?
Infection in pregnant cows leads to viremia and rapid fetal infection, leading to abortion
-there is variable autolysis
When are abortions most common with IBR infections?
Between 4-8 months
- dams may or may not have clinical signs
What are some post-mortem findings on necropsy of a fetus that died of IBR?
Varying degrees of autolysis, white tan foci on liver and lung, edematous placenta
When do opportunistic pathogens tend to cause abortion?
In the second half of gestation
Describe how cows get infected with neospora caninum
Dogs ingest tissue cysts in intermediate hosts and release unsporulated oocyts in feces. These can then be consumed by the cow if fecal contamination of food and water occurs. Once tachyzoites are transmitted through placenta, fetus can be infected
Compare/contrast endogenous and exogenous transmission of neospora?
Exogenous is when the cow gets infected during pregnancy and passes to babe. Endogenous is when cow gets infected in utero and then passes on infection to her calf after infection reactivates during pregnancy
When does abortion occur with neospora infections?
Early second trimester (5-6 months)
Describe how neospora affects the developing fetus?
It invades and damages the fetal placental villi
T/F: there is a vaccine for neospora
F- no vaccine and no treatment!
Which leptospirosis serovar leads to the highest abortion rate? during what trimester?
Serovar pomona leads to a 50% abortion rate during the third trimester (1-6 weeks after initial infection)
Serovar hardjo leads to a 3-10% abortion rate during the 2nd-3rd trimester (4-12 weeks after acute infection)
How is lepto transmitted?
Direct contact with infected urine, placental fluids, milk, or transplacental or venereal transmission
Describe the pathogenesis of lepto
After infection (takes 4-10 d to incubate) bacteremia allows bacteria to localize and persist in kidney and genital tract
-leads to persistent shedding of bacteria in urine and repro fluids
What are the findings on the fetus during necropsy in lepto case?
Fetuses autolyzed, icteric, diffuse cotyledonary necrosis
T/F: Listeria is zoonotic
True!
When does listeria cause abortions? How?
Last trimester- sporadic and rarely exceeds 15%
-causes meningoencephalitits and neonatal septicemia
In what weather are listeria infections most common?
cold temps
What are some fetal post mortem findings in listeria cases?
Multifocal cotyledonary necrosis, placentitis, fibrin polyserositis, and white necrotic foci in liver and spleen
When does brucellosis lead to abortions?
In the last trimester
-also causes premature calving, infertility in cows, orchitis in bulls
Describe the pathophysiology of brucellosis?
The mucosa of oral or nasal cavities are invaded, then localizes in lymph nodes.
-bacteremia allows spread to uterus leading to trophoblastic necrosis and chorioallantoic ulceration
What are some gross findings due to brucella infection?
Placenta may be dry, thickened, cracked (moroccan leather looking)
-intercotyledonary placenta may be covered by thick yellowish exudate
Why is the brucella vaccine restricted?
Human health concerns- can find virus in raw milk
When can aspergillus fumigatus lead to abortion in cows?
Late pregnancy (6-8 months)
Where is epizootic bovine abortion common?
California, Oregon, Nevada
-caused by the tick ornithodoros
-most abortions occur in 3rd trimester
What are some gross signs of infection with epizootic bovine abortion?
Petechial hemorrhage in mucosa of conjunctiva and oral cavity, enlarged lymph nodes, ascites, enlarged liver
When are cows most susceptible to infection with foothill abortion?
60-140 days (mid-gestation)
-slow infection
