Bovine Abortion Part 1 - Overview

What can circling vultures indicate in a pasture setting?

They may indicate an expelled fetus.

What is a classic case of early term fetal abortion in cows?

A cow previously diagnosed as pregnant is now no longer pregnant with an expelled fetus.

What are signs of early-term abortions in cows?

Return to estrus and delayed estrus following insemination.

What happens to a cow's estrus cycle following early-term fetal abortion?

The cow may return to estrus.

What does Blackleg infestation indicate in fetal age determination?

Cloudy corneas in fetuses indicate death roughly 12 hours prior.

Which organism is associated with early-term abortion in cattle?

Tritrichomonas foetus.

How is neosporosis primarily transmitted to adult cows?

Through canine fecal contamination of feed.

What may happen to calves born from cows infected with Neospora caninum?

They may be non-autolyzed and dead or born alive with varying severity of CNS disease.

What is the abortifacient found in ponderosa pine needles?

Labdane resin and isocupressic acid.

What does the presence of soft ticks indicate in relation to abortion in cattle?

They are vectors for foothill abortion.

What are the two primary causes of abortion associated with Chlamydia and Leptospira?

Chlamydia abortus and Leptospira spp. (various serovars).

What disease is recognized as a cause of abortion in the second half of gestation?

Brucella abortus.

What is the typical gestation period when abortions due to Brucella abortus are observed?

Around 7 months of gestation.

What is a potential diagnosis method for BVD in abortion cases?

PCR or fluorescent antibody tests.

How can nitrates cause abortions in cattle?

At intakes greater than 700 ppm nitrate in feed.

What prevention strategy helps keep abortion rates in cattle below 1%?

Good husbandry practices.

What vaccination is recommended against infectious bovine rhinotracheitis (IBR)?

Modified-live vaccines at 6 months of age with annual revaccination.

What is the recommended action for infected and at-risk cows regarding Campylobacter?

Vaccination.

What is the recommended intervention for nitrates in cattle feed?

Diluting or excluding feeds with toxic concentrations of nitrates.

What is the economical significance of Tritrichomonas foetus in relation to cattle?

It leads to fetal resorption, delayed estrus cycles, and is economically significant.

What should be done to prevent neosporosis in cattle?

Keep dogs away from cattle feed and pastures.

Classic case of abortion in cows?

Cows previously pregnant but now no longer are, we can find an expelled fetus, vaginal discharge or handing placenta. Vultures circling due to rotting tissue.

What happens in early term abotions?

They return to estrus and they can have delayed estrus following insemination

What can occur during late term abortions?

Dystocia, retained placenta, uterine discharge or fetus or remnants can remain in uterus

How can we determine how long fetus has been dead in utero?

12h - Cloudy cornea

24h - Soft and pulpy kidneys; cloudy, flocculent and mucoid abomasal contents

36-96h - SC tissue is gelatinous and blood tinged. Lifer is soft and friable. Abomasal content is pink-red

What are the causes of early/1 term gestation abortions?

Tritrichomonas foetus and heat

What occurs during trichomoniasis?

The fetus is reabsorbed and NOT expelled, the cow returns to estrus. They can have multiple breedings and delayed estrus cycles.

How is trichomoniasis transmitted?

Venereal transmission to and from bulls via infected cows.

How long is the trichomoniasis infection?

Cows have a short term vaginal infection with self cure and immunity, while bulls are permanently infected in the sheath

How does heat affect pregnancy?

Ambient temps >100C cause fever and fetal resporption

What are the causes of mid term abortions?

Neospora caninum

What is neospora caninum and how is it transmitted?

A protozoa which is transmitted through canine fecal contamination of feed (dogs are primary hosts and shed the oocytes) and also can occur vertically.

When does neospora caninum cause abortion and what are are the effects on the fetus/calf?

Mostly between 4-6 (possible between 3-9). Calves may be non autolyzed and dead, those born alive have varying severity of CNS diz

Causes of late term abortions?

Brucella abortus, epizootic bovine abortion, sarcocystis spp., chlamydia abortus, leptospira spp, listeria monocytogenes, mycoplasma/ureaplasma spp., nitrate poisoning, ponderosa pine needles, ergots, anaplasma marginale, drugs like dexamethasone and xylazine.

When does brucella abortion occur?

Second half of gestation around 7 mos.

How does brucella infection occur?

Pregnant cows get infected by contact with aborted fluids and tissues from infected cows. May cause abortion storm

Which causes of abortion are reportable?

Trichomoniasis, brucellosis

What causes foothill abortion?

Pajaroellobacter abortibovis, a G- rod transmitted by Ornithodorus coriaceus (soft tick or argasid tick)

Where does foothill abortion occur?

In the western US

When do foothill abortions occur?

60-120 days after naive heifers are moved to contaminated pastures. It wont occur if they’re >120 days.

What do fetuses aborted due to foothill have

Lymphadenopathy and petechial hemorrhages

What are the 5 common leptospirosis serovars?

Hardjobovis, Gryphotyphosa, Pomona, Canicola, Icterohemorrhagica

Fetuses aborted due to lepto characteristics?

White spots on kidneys and petechiae in scleral membranes

Lepto transmission?

Mostly environmental urine to oral transmission, except Hardjobovis which can be venereally transmitted

When does nitrate poisoning cause abortions?

When the intakes are over 700ppm nitrate in feed on a dry mater basis. Abortion can be delayed in respect to exposure.

CS of nitrate poisoning?

Muscle tremors, weakness anxiety. Brown or cyanotic MM, dyspnea or tachypnea. These are followed by abortions

How does ponderosa pine cause abortion?

The high dietary protein increases the risk of abortions

Concurrent CS of anaplasma infection?

Anemia and icterus + abortions

Which agents cause variable abortions in term of the timing?

BVD, campylobacter (vibrio) veneralis), exogenous prostaglandins, IBR, trueperella pyogenes

When can BVD abortions occur?

At any stage, also common 3-4 months

How do fetuses aborted due to BVD look?

Depending on the stage, can look normal or be in early stages of mummification

BVD transmission

Venereally from persistently infected bull semen

Hos is campylobacter transmitted?

Venereal from bull or cow to bull. Reinfection can occur after several years

What is PGF used for?

For mismating. Give 7-9 post mating then re dose in 7-9d. Used for pregnancy termination, but like dexa has a high risk of retained placenta.

IBR abortion time

Any time, but esp 4mos to term. They can abort weeks to months after last clinical case of IBR

Fetuses IBR?

White abomasal plaques

WHy is it hard to dx cause of abortion?

Because fetuses are autolyzed, physical non infectious causes may self correct, toxic agents have disappeared by the time abortion occurs

What spec to collect to dx cause of abortion?

1. Abomasal content (frozen or refrigerated)

2. Decomposed fetus ( frozen or refrigerated)

3. Kidney (f or r plus formalin)

4. Infected cotyledons (f/r and f)

5. Intestine (formalin)

6. Lung (f/r and f)

7. Serum (dam and fetus) or peritoneal fluid from fetus (f/r)

8. Vaginal discharge (f/r)

9. Any organ with lesion (formalin)

BVD test?

PCR or fluorescent Ab

N. caninum tests?

Titers on dam are very high in cases of abortion

Trichomoniasis tests?

• Confirm identity of + culture

• Non pathogenic intestinal trichomonads sometimes contaminate specimen

• Tag carrier bulls and report to state and neighbors

Campylobacter dx?

• Cervical mucus for Ab or culture and fetal tissues for culture

• Cow will eliminate it after several estrous cycles

Leptospira dx?

• Microscopic agglutination titers:

  • Short lived post abortion

  • Confusing if cow vaccinated

  • Vaccine titers rarely exceed 1:400

• PCR or fluorescent Ab on aborted fetal tissues and placentomes

IBR dx?

Immunofluorescence on fetal cotyledons, fetal abomasum, and fetal lung

Nitrates dx?

Analysis of water and feed (>700ppm dry matter)

B. abortus Dx?

Serology on dams blood, culture fetal abomasum contents

Foothill abortion Dx?

PCR on fetal tissues

Listeriosis Dx?

Culture placenta and fetal abomasum contents

IBR and BVD prevention?

Appropriate vaccination at 6mos with modified live vaccines and then annual revaccination pre breeding

B. abortion prevention?

RB 51 vaccine at 4-6mos

Leptospira prevention?

Vaccinate pre breeding and mid gestation. Identify hardjobovis carriers, treat carriers with long acting oxytetracycline

C. fetus prevetion?

Vaccinate infected and at risk cows

N. caninum prevention?

Keep dogs and other canines from commodities and pastures

T. foetus prevention?

Test bulls prior to introduction to cows and repeat test 2 or more times

Nitrates prevention?

Dilute or exclude feeds with toxic concentrations of nitrates

Foothill abortion prevention?

Wait until third trimester (>160 days) to introduce heifers to known infected pastures