Normal parturition in bovine

Question 1

Parturition means…

Answer 1

(partus, tocos) e. delivery: Expulsion of fully grown fetus and fetal membranes from the uterus through the birth canal.

Normal parturition (eutocia)

Right time (in cow, the length of pregnancy is 270 – 290 days).

One week before or after the term we consider as normal in cow.

Question 2

the length of pregnancy in days in the cow

Answer 2

270 – 290 days

Question 3

The Birth canal is divided into: (2)

Answer 3

Bony canal and soft tissues

Bony = (pelvis, 2 coxal bones, sacral bone)

Question 4

Obstetrical pelvimetry

Answer 4

is the assessment and measurement of the dimensions of the pelvis, particularly focusing on its suitability for vaginal delivery.

Not used much in practice (in vet med).

Pelvic cavity narrows in caudal direction.
Cranial and caudal terminal line anatomic points.

Question 5

Answer 5

Question 6

Answer 6

Question 7

Answer 7

Question 8

Fetal postures can change until

Answer 8

the beginning of first stage of parturition (opening of birth canal).

Before parturition fetus front legs will be extended towards to birth canal, but the elbow joints will be flexed.

Final extension of front legs will happen during the second stage of parturition (fetus expulsion stage).

In normal parturition the fetus will be born in anterior presentation, dorsal position and extended postures (front legs and head are extended toward the birth canal).

Question 9

Hormonal activity to induce parturition.

Answer 9

Activation of fetal hypothalamus-hypophysis-adrenal glands axis and fetal cortisol release.

Placental origin estrogens, progesterone, PGF2α and corticotropin release factor (CRF) will influence hypothalamus.

Question 10

Two major endocrine-change events in the dam aiding parturition:

Answer 10

1. Removal of the myometrial „progesterone block“ enabling myometrial contractions to begin.

Fetal cortisol promotes the synthesis of three enzymes that convert progesterone to estradiol.

2. Increased reproductive tract secretions (particularly by the cervix).

Fetal cortisol triggers androstenedione which is converted finally to estrogen (initiates secretory activity of the reproductive tract in general and particularly the cervix).

Question 11

Progesterone block removal“

Answer 11

Fetal cortisol promotes the synthesis of three enzymes that convert progesterone to estradiol.

Question 12

Relaxin is a Glycoprotein that is produced by

Answer 12

either the CL or the placenta, depending upon the species.

Synthesis is stimulated by PGF2α.

Question 13

In the cow, from 150 – 200 days of pregnancy the main source of progesterone is

Answer 13

the placenta, however the presence of CL in an ovary is necessary until parturition.

If we will remove the CL after day 200 of pregnancy, the pregnancy will continue, but the normal hormonal mechanism which will cause the start of parturition process will be disturbed.

Question 14

Body temperature in cows before parturition.

Answer 14

Body temperature rise during last months of pregnancy 38.8° – 39.3°, when parturition approaches 39.4° – 39.7°.

Sharp drop 12h before parturition (as low as 38°).

Question 15

According to what 3 factors can we predict the parturition time in all cows with accuracy 22h?

Answer 15

pelvis ligament relaxation,
body temperature drop
and progesterone level decrease

Question 16

define Ferguson reflex

Answer 16

a neurohormonal reflex that triggers strong uterine contractions during labor. It is initiated when the fetal head presses against the cervix, stimulating stretch receptors.

This pressure sends nerve signals to the hypothalamus, leading to the release of oxytocin from the posterior pituitary gland.
Oxytocin then increases the strength and frequency of uterine contractions, further enhancing cervical stretch and facilitating labor progression. This positive feedback loop continues until delivery occurs.

Question 17

On average up to ? abdominal muscle contractions are needed for expulsion of fetus.

Answer 17

On average up to 60 abdominal muscles contractions are needed for expulsion of fetus.

Question 18

An Opening cervix feels…?

Answer 18

shorter in rectal palpation

Question 19

Stages of birth:

Answer 19

1. opening of the birth canal.
2. fetal expulsion stage.
3. expulsion of fetal membranes.

Question 20

Describe opening of the birth canal.

Answer 20

very difficult to determine the beginning of it (beginning of labor). Duration approx. 2-6 h.

Cow is restless, apparent discomfort, cessation of eating, pawing the ground, circling. Lying down and then fairly quickly rising again.

bluish, vascular semitransparent membrane appearing at the vulva is the chorioallantois. It may be termed the „the first water bag“.

Its rupture together with appearance of fetal front legs and head in vagina is considered also as end of the first stage of birth.

Question 21

Describe the Second stage of birth (fetus expulsion stage):

Answer 21

length of the stage is 0.5–4h (average 70 min)

The calf is normally preceded by its amnion as it enters the birth canal and unless prior rupture occurs, the amnion appears as a gray-white avascular sac at the vulva (different to the earlier blue one, the chorioallantois.

The calf should be born within 2 hours of the first appearance of the amnion at the vulva

During second stage of birth one uterine contraction lasts 1 – 2 min (during that time several abdominal contractions).

During delivery, the position of the calf may rotate approximately 45⁰ to the right or left allowing it to take advantage of the greatest pelvic diameter of the mother.

Question 22

In case of twins, after the expulsion of first fetus the labors will cease for

Answer 22

10 – 15 min and then the second fetus will be delivered.

Question 23

The calf should be born within ? hours of the first appearance of the amnion at the vulva.

Answer 23

The calf should be born within 2 hours of the first appearance of the amnion at the vulva.

Although the bovine fetus can survive for up to 8 hours during the second-stage of labor, this is not always the case and any delay should be investigated.’

Question 24

What stimulates the calf to breath at birth?

Answer 24

Obstruction of umbilical cord,
increase in carbon dioxide,
stimulation of respiratory center.

Question 25

Describe the Expulsion of fetal membranes stage:

Answer 25

For fetal placenta separation from mother placental maturation should taken place.
The same hormonal cascade which leads to parturition leads to placental maturation.

Caruncular crypt epithelium will degenerate. After the rupture of umbilical cord, the placentome tissue turgor will decrease with uterine contractions.

Cotyledon villi will separate from caruncular crypts and fetal membranes will be expelled.