Fetal abortion

Question 1

What is the difference between embryo and fetus?

Answer 1

Embryo:
- product of conception (zygote)
- used to define the embryonic mass that has not yet reached the stage of differentiation

Fetus:
- From the completion of differentiation onwards

Question 2

What is the difference between resorption and abortion?

Answer 2

Resorption – loss of the embryo
Abortion – loss and expulsion of the fetus

Question 3

Describe progesterone levels throughout pregnancy.

Answer 3

1. Ovulation occurs
2. P4 goes up & plateaus
3. P4 falls just before parturition

P4 levels vary between species
- In some P4 is produced entirely by CL (ovarian production of P4) throughout pregnancy
- In other species placenta takes over (luteal-placental shift)

Question 4

What are the possible outcomes of fetal death?

Answer 4

Abortion – Expulsion after P4 decline & uterine contractions

Mummification – Dehydration of fetus, P4 maintained, no bacteria

Maceration – Bacterial invasion, putrefaction, incomplete expulsion

Stillbirth – Fetus reaches full term but dies during delivery

Question 5

What are some common non-infectious causes of pregnancy loss?

Answer 5

Genetic abnormalities

Uterine disease (not able to form effective placenta)

Stress (nutritional, heat, other)

Maternal illness

Nutritional phytotoxins

Question 6

What are the infectious causes of pregnancy loss?

Answer 6

Exposure to reproductive pathogens
- Not always venereal – Many infections occur after pregnancy begins

Recrudescence of latent viral infections

Ascending infections (e.g. placentitis)

Few bacterial venereal pathogens cause pregnancy loss:
- CEM in mares → endometritis only
- Campylobacteriosis in cattle → Endometritis but may cause abortion if persistent