Pregnancy failure

Question 1

Describe pseudopregnancy following pregnancy loss

Answer 1

• Loss occurs after MRP
• CL doesn’t regress
• P4 secretion stays high
• Results in pseudopregnancy
• Occurs in mares, goats, sows, queens

Question 2

What is cloudburst?

Answer 2

• Hydrometra

- Embryonic death- CL persists and accumulation of sterile secretions builds up in uterus.

Question 3

How do chromosomal abnormalities occur?

Answer 3

• Abnormal meiosis
• Polyspermic fertilisation
• Failure to extrude polar bodies
• Failure of meiosis

Question 4

List some causes of embryonic and foetal loss

Answer 4

• Nutrition: vit A/ E deficiency
• Environment: stress, temperature, teratogens
• Infectious agents
• Trauma
• Insemination: poor semen quality

Question 5

Are we able to determine precisely developmental stage affected?

Answer 5

No, more than one stage may be affected.

Question 6

How can pathogens enter the pregnant uterus?

Answer 6

• Cervix (ascending infections): cervical incompetence
• Systemic infection (i.e. blood): endometrium/ placenta/ foetus
• Pathogens may effect the CL (IBR)

Question 7

List the venereal pathogens that can cause early embryonic death

Answer 7

• Bacteria in cattle: Campylobactor fetus
• Protozoa in cattle: Tritrichomonas fetus
• Bacteria in horses: Taylorella euigenitalis

Question 8

Discuss pyometra in cattle following loss of pregnancy

Answer 8

• Trichomonas fetus: protozoal disease-CL persists and cervix closes resulting in pus accumulation in uterus

Question 9

In which species is it more common for aborted fetus to be in a state of autolysis?

Answer 9

• Species with CL dependant pregnancy
• Because there is a delay between time of death and lysis of CL
• In CL independent species fetal death leads to cessation of fetal contribution so P4 declines and fetus expelled more rapidly.

Question 10

What can cause mummification in the bitch?

Answer 10

-Canine herpes virus

Question 11

What does SMEDI stand for and what are the classical signs?

Answer 11

Stillborn Mummification 
Embryonic 
Death
Infertility 
-Full term litter consisting of mummified piglets of different sizes
-It is a progressive infection in utero

Question 12

What is SMEDI often caused by?

Answer 12

• Porcine parvovirus
• PRRS (porcine reproductive respiratory syndrome)
• Less often by enteroviruses

Question 13

is the main cause of equine abortion infectious?

Answer 13

• NO

- Only 15% caused by infectious diseases

Question 14

What are the common infectious agents of abortion in the mare?

Answer 14

BACTERIAL:
Streptococcus zooepidemicus and E.coli–> these cause placentitis
FUNGAL: Aspergillus–> causes placentitis
VIRAL: Equine herpesvirus-1, Equine arteritis virus–> these infect the placenta AND fetus

Question 15

Explain equine twinning and pregnancy failure

Answer 15

• Equine placenta= epitheliochorial, the embryo needs all the SA to be sustained= remember microcotyledons.
• When twins are present the placental interface cannot get close enough to foetuses to absorb sufficient nutrients
• One fetus may be resorbed at early stage OR one fetus may be mummified at early stage OR both twins aborted at mid-late gestation.

Question 16

What are the common infective agents causing ovine abortion?

Answer 16

• Most commonly caused by infectious diseases
• Chlamydophila abortus
• Toxoplasma gondii
• Schmallenberg virus

Question 17

What fetal malformations are caused by Schmallenberg virus?

Answer 17

• Athrogryposis: stiff limbs due to muscles developing properly
• Hydraneceophaly: water on the brain
• Bracynathia: undershot jaw ‘parrot jaw’

Question 18

What part of the body does Schmallenberg target?

Answer 18

CNS
-if it infects at a critical point of CNS development it has huge impacts on the embryo= sheep between 2/3 months and cattle between 3/5 months

Question 19

Discuss chlamydial abortion (enzootic) abortion of ewes

Answer 19

• It is the main cause of ovine abortion in the UK
• Causes abortion in the last 3 weeks of pregnancy= very late because it lies dormant until day 90ish due to immune system.
• Placental inflammation caused
• Pathological features= placenta is thickened in intercotyledonary areas and has BROWNISH EXUDATE

Question 20

What is the main cause of ovine abortion in the UK?

Answer 20

-Chlamydophila abortus

Question 21

Discuss Toxoplasma gondii infection in the pregnant ewe

Answer 21

• It is a protozoan infection
• Timing of infection determines impact on fetus = worse earlier on
• Causes lesions in brains, liver and kidney of fetus
• Dark red cotyledons with white specks of necrosis BUT intercotyledonary areas are normal

Question 22

What is the affect of Campylobacter species on ovine abortion?

Answer 22

• Abortion occurs in last 6 weeks of gestation or sickly live lambs born
• No lesions present in placenta BUT areas of necrosis can be seen in fetal liver

Question 23

What is the most common infectious abortive agent in the cow?

Answer 23

-Neospora species

Question 24

At what stage of gestation will infection with Bovine BVD result in a PI?

Answer 24

• Days 90-120= this is before immunocompetance is formed : fetus will either die or be a PI
• If before day 90 then will result in abortion of mummification
• If after day 125-150 then immunocompitence is achieved and has no effect on the calf