Parturition

Question 1

Stages of Parturition

Answer 1

Stage of preparation
First stage
Second stage
Third stage

Question 2

Stage of preparation

Answer 2

1. Production of relaxin
   ○ Causes relaxation of soft tissues of reproductive tract and perineum
2. Fetal maturation

Question 3

First stage parturition

Answer 3

3. Stimulates increase in PG and decrease in progesterone from CL or placenta
4. Increase in relaxin allowing cervix to dilate
5. Results in myometrial excitability and onset of uterine contractions
6. Fetus assumes position for expulsion

Question 4

Second Stage Parturition

Answer 4

7. Uterine contractions push fetus into birth canal
8. Abdominal contraction are additive
9. Ferguson’s reflex produces additional uterine contractions
10. Fetus delivered

Question 5

Third stage parturition

Answer 5

11. Abdominal contractions largely cease
12. Myometrial contraction decrease in amplitude but are more frequent and less regular
13. Placenta expelled

Question 6

How does 2nd/3rd stage differ in polytocous species

Answer 6

2nd and 3rd stage overlap
Occurs between each fetus delivery

Occurs separately monotocous species

Question 7

Chronology of second stage parturition in different species

Answer 7

Second stage is complete when all foetuses have been delivered
○ Mare - 30 minutes
○ Cow - 1 hour
○ Ewe - 1 hour
○ Queen - 2 hours
○ Sow - 3 hours
○ Bitch - 6 hours

2nd stage is longer in polytocous species

Question 8

Dystocia

Answer 8

Difficulty in parturition
~5% of parturitions rest in dystocia
* varies according to:
○ Species
○ Breed
○ Age of dam
○ Match of sire to dam

Question 9

Dystocia in cows

Answer 9

• Heifers may be bred at an early age
  ○ Dystocia common
• Breed important
  ○ Holstein have high incidence
• Beef sires often used resulting in large calf
  ○ Feto-maternal disproportion is common
  ○ Common challenges are establishing if calf is deliverable
• Faulty disposition is less common
• Twin pregnancies occur and have 2.5x greater risk
• Fetal monsters not uncommon
• Maternal dystocia is uncommon
  ○ Include incomplete cervix dilation, and uterine inertia due to hypocalcaemia