PHYSIOLOGY - Parturition and Neonatal Adaptation

Question 1

Why is progesterone production so important during gestation?

Answer 1

Progesterone reduces myometrial contractions allowing the uterine myometrium to remain in a state of quiescence during gestation essential for foetal development

Question 2

Which two structures produce progesterone during gestation?

Answer 2

Placenta
Corpus luteum (regresses in most species as the placenta develops)

Question 3

Which species relies on both the placenta and the corpus luteum for progesterone production during gestation?

Answer 3

Bovine (Cow)

Question 4

What are the two essential changes that must occur within the female reproductive tract to allow parturition to occur?

Answer 4

Coordinated uterine myometrium contraction
Dilation of the cervix

Question 5

What stimulates parturition?

Answer 5

Hypothalamic-pituitary-adrenal (HPA) axis activity in the foetus leading to a surge in adrenal foetal cortisol production

Question 6

How does foetal cortisol alter the steroid hormone ratio in the placenta?

Answer 6

Foetal cortisol travels to the placenta and stimulates 17α hydroxylase which converts the progesterone precursor pregnenalone into oestrodiol. This leads to an increase in oestrodiol and decrease in progesterone in the maternal circulation

Question 7

What are the three steps of parturition?

Answer 7

1. Preparation
2. Expulsion of the foetus(es)
3. Placenta expulsion and first suckling/standing

Question 8

What occurs during the first stage of parturition?

Answer 8

The foetus changes position within the uterus and enters the birth canal

Question 9

What are some of the behavioural changes seen during the first stage of parturition?

Answer 9

Restlessness, sweating, raising tail, vomiting, looking back at the abdomen, nesting, grumbling and licking of other neonates

Question 10

Why does the bitch often vomit during the first stage of parturition?

Answer 10

The bitch will often vomit during the first stag of parturition as a side affect of the PGF2α that is secreted from the placenta

Question 11

What is the hormone which causes behavioural changes in the dam to prepare her for mothering (nesting etc..)?

Answer 11

Prolactin

Question 12

What are some of the physical signs of the onset of parturition?

Answer 12

Mammary gland oedema
Dripping colostrum (Waxing)
Temperature decline
Relaxation of pelvic ligaments
Expulsion of cervical plug

Question 13

What occurs to signify the end of the first stage of parturition?

Answer 13

Bursting of the allantois

Question 14

What occurs during the second stage of parturition?

Answer 14

Foetus is delivered and expulsed through the birth canal within the amnion (which may or may not burst)

Question 15

How long should foetal expulsion take once to foetus can be seen within the birth canal?

Answer 15

Foetal expulsion should occur within 15-20 minutes

Question 16

What are the two reflexes which occur during the second stage of parturition?

Answer 16

Ferguson reflex
N. pudendus reflex

Question 17

What is the Ferguson reflex?

Answer 17

The Ferguson reflex is a neuroendocrine reflex where vaginal and cervical stretching results in oxytocin release from the posterior pituitary gland increasing myometrial contractions

Question 18

What is the N. pudendus reflex?

Answer 18

The N. pudendus reflex is a spinal reflex where vaginal stretching stimulates abdominal contractions

Question 19

What happens to the dam during the third stage of parturition?

Answer 19

Placenta is delivered and the onset of puerperium (postpartum) and lactation occurs

Question 20

Within how may hours should the entire placenta be shed after birth in the mare?

Answer 20

The entire placenta should be shed within three hours

Question 21

What are the complications of a retained placenta in the mare?

Answer 21

Metritis which can lead to septicaemia or endotoxaemia

Question 22

What can be used to treat a retained placenta in the mare?

Answer 22

Oxytocin therapy
Fluid therapy

Question 23

What happens to the neonate during the third stage of parturition?

Answer 23

Onset of post-natal development, suckling and standing

Question 24

What are ‘foal slippers’?

Answer 24

‘Foal slippers’ are soft tissue present on the hooves of the neonatal foal which should break off as soon as they stand

Question 25

What is flexural laxity a sign of in the neonatal foal?

Answer 25

Flexural laxity is a sign of prematurity or dysmaturity but can also be commonly seen in the hind limbs of larger equine breeds

Question 26

What are the three main risks to the neonate at the start of it’s extra-uterine life?

Answer 26

Hypoxia
Hypothermia
Hypoglycaemia

Question 27

What are the three hormones responsible for postnatal survival of the foetus?

Answer 27

Cortisol
Catecholamines
Thyroid hormone

Question 28

What are some of the essential perinatal metabolic processes which are essential for the postnatal survival of the foetus?

Answer 28

Initiation of breathing
Thermogenesis
Glycolysis
Gluconeogenesis
Organ maturation
Maturation of the circulatory system

Question 29

What are the three postnatal lung adaptations that need to occur to allow survival of the neonate?

Answer 29

Clearance of foetal lung fluid from the alveoli
Surfactant production
Achievement of a continuous breathing pattern

Question 30

What achieves thermogenesis within the first few hours of neonatal life?

Answer 30

Thermogenesis is achieved by brown adipose tissue and non-shivering thermogenesis

Question 31

What are the three adaptations found in foetal circulation?

Answer 31

Ductus venosus
Foramen ovale
Ductus arteriosus

Question 32

What is the function of the Ductus venosus, Foramen ovale and Ductus arteriosus in the foetal circulation?

Answer 32

In utero, gas exchange occurs at the level of the placenta and not the lungs due to the high pulmonary vascular resistance compared to the low resistance placenta. The Ductus venosus, Foramen ovale and Ductus arteriosus allow the majority of the foetal circulation to bypass the lungs (as well as the liver) to reach the placenta

Question 33

Why do the Ductus venosus, Foramen ovale and Ductus arteriosus need to be closed off after birth?

Answer 33

To complete the maturation of the foetal circulation into a neonatal circulation where the gas exchange occurs at the level of the lungs

Question 33

How does the ingestion of colostrum assist in the neonatal passing of meconium?

Answer 33

Colostrum has a laxative effect on meconium

Question 34

How should colostrum be administered to a neonate with insufficient colostrum?

Answer 34

Nasogastric tube