Parturition and dystocia

Question 1

List the 3 stages of parturition

Answer 1

1) Initiation of myometrial contraction
2) Expulsion of the foetus
3) Expulsion of the foetal membranes

Question 2

What initiates parturition?

Answer 2

-Hormonal signals from foetus= FOETAL CORTISOL

Question 3

What does puerperium mean?

Answer 3

Stage between parturition and when cycle starts again

Question 4

What does the stage of preparation for parturition involve?

Answer 4

• Production of relaxin
• Relaxin= produced in placenta of horse/ dog/ cat but produced in CL in ruminants/ sow
• Relaxin causes increased elasticity of the pubic symphysis, vulval and perineal tissues

Question 5

Describe stage 1 of parturition

Answer 5

• Increased foetal cortisol- enzymes activated which switch P4 to E2- increased E2 causes increased repro tract secretions (lubrication)- decreased P4 removes inhibition on myometrial contractions
• Increased foetal cortisol also causes increased prostaglandin which causes lysis of CL (if present) and also increases relaxin to remodel cervix etc

Question 6

What effect do uterine contractions have on the placenta?

Answer 6

-Cause the placental attachments to the endometrium to loosen.

Question 7

What are the signs of first stage parturition?

Answer 7

• Uterine (not abdominal) contractions
• Shivering
• Nesting behaviour
• Vulval discharge

Question 8

In which type of species can second/ third stage parturition not be separated?

Answer 8

-Polytocous

Question 9

What are the signs of second stage parturition?

Answer 9

-Onset of abdominal contractions

Question 10

Describe Fergusons reflex

Answer 10

• Abdominal/ uterine contractions–> push foetus against cervix –> neuro–hormonal reflex stimulated causing the brain to release oxytocin –> results in myometrial contractions
• Fergusons reflex is separate to the abdominal contactions!

Question 11

How much of the workload do uterine contractions do?

Answer 11

90%

Question 12

What is the stimulus to breathing?

Answer 12

The air hitting the nostrils

Question 13

When the umbilical ruptures, what prevents haemorrhage?

Answer 13

-The two umbilical arteries and urachus retract into the abdomen

Question 14

Describe the events that occur during second stage parturition

Answer 14

• Abdominal/ uterine contractions
• Fergusons reflex (NOT part of abdominal contractions)
• ALLANTOCHORION ruptures due to movement against vulva
• Contractions continue and AMNION ‘water bag’ is visible
• Foetus becomes hypoxic once enters the birth canal
• Forceful contractions continue
• Foetus either both inside amnion or it ruptures during birth.

Question 15

During third stage parturition what do the uterine contractions do?

Answer 15

• Cause the opening of endometrial crypts
• Removal of the placenta
• Separation of the foetal membranes

Question 16

Describe the expulsion of the placenta in the mare

Answer 16

• Has a diffuse placenta so the apex of the allantochorionic sac starts to invert as the foal exits
• Foal bursts through the cervical start within the amnion and the placenta everts as it is pulled out
• When the placenta is out it is the allanchoic (fetal) side you see

Question 17

What happens during puerperium?

Answer 17

-The reproductive tract reduces in size similar to that before pregnancy

Question 18

Define the term foetal disposition

Answer 18

The spatial arrangement of the foetus relative to the pelvis and the birth canal of the dam

Question 19

What does the foetal position indicate?

Answer 19

• The quadrant of the dam’s birth canal that the foetus’ vertebrae is next to
• Dorsal position, ventral position, right lateral position, left lateral position

Question 20

What does the term foetal posture relate to?

Answer 20

The disposition of the moveable appendages of the foetus, involves flexion/ extension of the neck and limb joints e.g. diving position is in the extended posture

Question 21

What are the common causes of dystocia?

Answer 21

• Foetus too big/ too small
• Abnormal foetal disposition
• Multiple foetuses
• Uterine inertia

Question 22

In dogs what is the primary cause of dystocia?

Answer 22

-Primary intertia

Question 23

What is the term used for correcting presentation, position or posture?

Answer 23

Mutation

Question 24

What is repulsion?

Answer 24

Pushing the fetus out of the pelvis and back into the abdomen to give you more room to reposition

Question 25

What angle gives the largest diameter of the birth canal?

Answer 25

5 past 7 or 5 to 5

i.e. diagonal

Question 26

Why do you have to be careful once the foetus enters the birth canal?

Answer 26

• The umbilical cord is obstructed and so the foetus becomes hypoxic.
• Once the umbilicus engages the pelvis you have to deliver very fast. Especially if in caudal longitudinal presentation.