Pregnancy failure across species Flashcards
What are the key hormone changes during pregnancy in the mare?
Early pregnancy: Progesterone (from the corpus luteum) rises to maintain pregnancy.
~40 days: Equine Chorionic Gonadotropin (eCG) is produced by endometrial cups, supporting secondary CL formation and further progesterone production.
~120-150 days: Luteo-placental (L-P) shift occurs—progesterone production shifts from the CL to the placenta.
After L-P shift: Progesterone declines, and estrogen levels rise.
Late pregnancy (~280 days): Estrogen peaks and gradually declines near parturition.
Exogenous Prostaglandins (PG): Cause resorption early but have no effect after L-P shift.
What are the key differences between embryonic death, fetal death, stillbirth, mummification, and maceration?
Embryonic death: Occurs early in pregnancy, often leads to resorption.
Fetal death: Happens after fetal mineralization, may result in mummification or expulsion.
Stillbirth: A full-term fetus that dies before or during birth.
Mummification: Fetal death without bacterial infection, leading to desiccation.
Maceration: Fetal death with bacterial invasion, causing tissue breakdown.
How does the timing of pregnancy loss affect the clinical outcome?
Early embryonic death: Resorption.
Fetal death before luteoplacental shift: Mummification is possible if CL persists.
Fetal death after luteoplacental shift: Expulsion is more likely.
How does maternal recognition of pregnancy and luteoplacental shift affect pregnancy loss outcomes?
If the CL is required throughout pregnancy (e.g., sow, bitch), fetal death may lead to mummification.
If a luteoplacental shift occurs early (e.g., mare, ewe), fetal death leads to expulsion rather than mummification.
Why are multiple conceptuses a common cause of pregnancy loss in mares?
Multiple ovulations result in multiple CLs.
Early detection allows selective crushing of one embryo.
After day 17, fixation occurs, making reduction harder.
Competition for placental space can lead to loss.
What are the likely outcomes of fetal death in species with no luteoplacental shift (e.g., sow, bitch, rabbit)?
Fetal death often leads to mummification because the CL persists.
Exogenous prostaglandin can terminate pregnancy at any stage.
Why does pregnancy failure in cows not always lead to immediate fetal expulsion?
The luteoplacental shift occurs late (210-250 days), meaning a dead fetus may remain in the uterus.
This delay increases the risk of mummification or maceration.
What is the significance of placentitis in mares?
Poor vulval conformation can lead to bacterial contamination.
Since the cervix is open in late pregnancy, bacteria can reach the placenta.
Can cause fetal growth restriction, septicemia, or abortion.
Local antibiotic therapy may help prolong pregnancy.
