Difference between revisions of "Normal Parturition - Anatomy & Physiology"

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{{OpenPagesTop}}
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<big><center>[[Reproductive System|'''BACK TO REPRODUCTIVE SYSTEM''']]</center></big>
==Stages of Parturition==
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<big><center>[[Reproductive_System#Parturition|'''BACK TO PARTURITION''']]</center></big>
  
*Stage 1: this is the preparatory stage, starting at the onset of regular uterine contractions followed by cervical dilatation and the foetus assuming the correct disposition for passage through the birth canal.
 
*Stage 2: the expulsive stage, characterised by the onset of abdominal contractions which together with uterine contractions lead to foetal expulsion
 
*Stage 3: separation and expulsion of the foetal membranes. In polycotous species second and third stages are often inter-mixed.
 
  
The following table summarises the normal time taken to progress through the stages of parturition in different species.
 
 
{| style="width:75%; height:200px" border="1"
 
{| style="width:75%; height:200px" border="1"
  
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| '''Stage 2: Foetal Expulsion'''
 
| '''Stage 2: Foetal Expulsion'''
 
| 12-30 minutes
 
| 12-30 minutes
| 30 minutes - 4 hours
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| 30-60 minutes
 
| 30-120 minutes
 
| 30-120 minutes
 
| 150-180 minutes
 
| 150-180 minutes
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The step in the reproductive process that immediately precedes lactation, uterine involution and return to cyclicity.  It is initiated by the foetus and involves a complex cascade of endocrine events. Parturition is the process by which the conceptus (foetus, placenta and placental membranes) is expelled from the [[Uterus - Anatomy & Physiology|uterus]]; this requires [[Cervical Softening - Anatomy & Physiology|cervical softening]],[[Uterine Contraction - Anatomy & Physiology|coordinated myometrial contractions]] and contraction of abdominal muscles
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to occur
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Parturition is the Process by which the conceptus (foetus, placenta and placental membranes) are expelled from the [[Female_Reproductive_Tract_-The_Uterus_-_Anatomy_%26_Physiology|Uterus]] requires:
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* [[Parturition - Cervical Softening - Anatomy & Physiology|Cervical Softening]]
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* [[Parturition - Coordinated Myometrial Contraction - Anatomy & Physiology|Coordinated Myometrial Contraction]]
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* Voluntary contraction of abdominal muscles
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 +
 
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= Stage 3: Placental Expulsion =
 +
 
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In most species, expulsion of foetal membranes quickly follows expulsion of the foetus. 
 +
 
 +
* After the birth of the young, regular abdominal contractions largely cease.
 +
* Myometrial contractions persist.
 +
** Decreased amplitude, but become more frequent and less regular.
 +
** Important for dehiscence and expulsion of foetal membranes.
 +
* Waves of contractions from uterus to the cervix persist.
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** Act in a peristaltic fashion in the cow and sow in the reverse direction.
  
 
== Placental Changes ==
 
== Placental Changes ==
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* Open endometrial crypts
 
* Open endometrial crypts
 
* Foetal villi have shrunk due to the escape of blood from the foetal side of the placenta when the umbillical cord ruptures.
 
* Foetal villi have shrunk due to the escape of blood from the foetal side of the placenta when the umbillical cord ruptures.
* [[Uterine Contraction - Anatomy & Physiology|Myometrial contractions]] aid exsanguination of the placenta.
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* Myometrial contractions aid exsanguination of the placenta.
 
* Separation of foetal membranes.
 
* Separation of foetal membranes.
 
* Apex of the allantochorionic sac becomes inverted.
 
* Apex of the allantochorionic sac becomes inverted.
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** Not the mare or camelids.
 
** Not the mare or camelids.
  
== Placental Expulsion ==
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= Parturition Behaviour =
  
In most species, expulsion of foetal membranes quickly follows expulsion of the foetus.
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== Mare ==
 +
 
 +
=== Stage 1 ===
 +
 
 +
* Mammary hypertrophy, waxing of the teats and possible escape of milk from the glands.
 +
* Patchy sweating behind the elbows and around the flanks.
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** Commences ~4 hours before the birth of the foal and increases as the stage progresses.
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* Yawns
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* No indication of pain.
 +
* Food is taken readily
 +
* Respirations are normal
 +
* Pulse is ~60
 +
* Body temperature may become slightly subnormal (36.5-37◦C).
 +
* Restlessness, wanders aimlessly.
 +
* Tail is frequently raised or held to one side.
 +
* May swish the tail or slap it against the anus.
 +
* Kicking of the abdomen
 +
* Towards the end of this stage:
 +
** Crouching
 +
** Straddling of hindlimbs
 +
** Going down on knees or sternum and rising again
 +
** Glancing at flank
 +
* This stage terminates with the rupture of the allantochorionic membrane and the escape of allantoic fluid from the vulva.
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** No visible straining during this period.
 +
 
 +
=== Stage 2 ===
 +
 
 +
* Abrupt onset, lasts~17 minutes
 +
* Appearance of the amnion or commencement of forceful straining
 +
** Not much delay between them, often coincide.
 +
* Soon after straining begins, the mare goes down.
 +
* Lies on her side with the limbs extended
 +
** Generally remains in this position until the foal is born.
 +
* Transperent blue/white 'water bag' (amnion) visible at the vulva
 +
* Quickly followed by the appearance in it of a digit.
 +
* Straining at regular intervals.
 +
** Each comprises 3/4 powerful expulsive efforts followed by a period of rest.
 +
** Generally 3 minutes long
 +
* One forelimb procedes the other by 7-8cm
 +
** One elbow passes through the pelvic inlet before the other preventing minimal obstruction.
 +
* Head is usually in the oblique position, but may be transverse with the cheek lying on the limbs.
 +
* Greates and longest effort is with birth of the head.
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* After expulsion of the foal, the mare may remain on her side exhausted for up to 30 minutes.
 +
* Umbillical cord is intact when the foal is born.
 +
** Subsequently ruptures 5-8cm below the belly due to movement of the mare or foal.
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* Foal is usually born within the amnion, which is ruptured by movements of the forelegs.
 +
* Lower portions of the hindlimbs often remain within the vagina for minutes after the rest of the foal is born.
 +
 
 +
=== Stage 3 ===
 +
 
 +
* Membranes expelled quickly after the birth of the foal.
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* Usually within 3 hours.
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* Duration of stage 3 is ~30 minutes.
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* Afterbirth is expelled by myometrial contractions with no straining.
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 +
== Cow ==
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 +
=== Stage 1 ===
 +
 
 +
* Lasts ~6 hours
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* Relaxing of pelvic ligaments.
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* Mammary secretions change from transparent,honey-like to opaque, cellular colostrum.
 +
* Body temperature subnormal by ~0.6◦C.
 +
* Parturition will begin 12 hours after complete relaxation of the posterior borders of the sacrosciatic ligaments.
 +
* Heifers may show signs of abdominal pain for up to 24 hours before the cervix is fully dilated.
 +
* Occasional straining may occur.
 +
* Picks at feed, irregular rumination
 +
* 'Lowing'
 +
* Kicking of the abdomen
 +
* Restless, may stand with her back arched and tail raised.
 +
** May go down and rise again frequently
 +
* Pulse rate often increased to 80-90.
 +
 
 +
=== Stage 2 ===
 +
 
 +
=== Stage 3 ===
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 +
== Ewe ==
 +
 
 +
== Sow ==
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 +
=== Stage 1 ===
 +
 
 +
=== Stage 2 ===
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 +
=== Stage 3 ===
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 +
== Bitch ==
  
* After the birth of the young, regular abdominal contractions largely cease.
+
=== Stage 1 ===
* Myometrial contractions persist.
 
** Decreased amplitude, but become more frequent and less regular.
 
** Important for dehiscence and expulsion of foetal membranes.
 
* Waves of contractions from uterus to the cervix persist.
 
** Act in a peristaltic fashion in the cow and sow in the reverse direction.
 
  
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=== Stage 2 ===
  
== Parturition Behaviour ==
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=== Stage 3 ===
  
=== [[Parturition Behaviour - Mare|Mare]] ===
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== Cat ==
  
===[[Parturition Behaviour - Cow| Cow]] ===
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=== Stage 1 ===
  
===[[Parturition Behaviour - Ewe| Ewe]] ===
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=== Stage 2 ===
  
===[[Parturition Behaviour - Sow| Sow]] ===
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=== Stage 3 ===
  
===[[Parturition Behaviour - Bitch| Bitch]] ===
 
  
===[[Parturition Behaviour - Cat| Cat]] ===
 
  
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<big><center>[[Reproductive System|'''BACK TO REPRODUCTIVE SYSTEM''']]</center></big>
  
{{OpenPages}}
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<big><center>[[Reproductive_System#Parturition|'''BACK TO PARTURITION''']]</center></big>
[[Category:Parturition]]
 
[[Category:Bullet Points]]
 

Revision as of 08:49, 6 August 2008

BACK TO REPRODUCTIVE SYSTEM
BACK TO PARTURITION


Species Mare Cow Ewe Sow Bitch
Stage 1: Contractions and Cervical Dilation 1-4 hours 2-6 hours 2-6 hours 2-12 hours 6-12 hours
Stage 2: Foetal Expulsion 12-30 minutes 30-60 minutes 30-120 minutes 150-180 minutes 6 hours (up to 24 hours with large litters)
Stage 3: Placental Expulsion 1 hour 6-12 hours 5-8 hours 1-4 hours Placenta Exits with Foetus



Parturition is the Process by which the conceptus (foetus, placenta and placental membranes) are expelled from the Uterus requires:


Stage 3: Placental Expulsion

In most species, expulsion of foetal membranes quickly follows expulsion of the foetus.

  • After the birth of the young, regular abdominal contractions largely cease.
  • Myometrial contractions persist.
    • Decreased amplitude, but become more frequent and less regular.
    • Important for dehiscence and expulsion of foetal membranes.
  • Waves of contractions from uterus to the cervix persist.
    • Act in a peristaltic fashion in the cow and sow in the reverse direction.

Placental Changes

During the last 5 days of gestation, there are changes in the placenta.

  • Collaginisation of the placentome.
  • Flattening of maternal crypt epithelium.
  • Leucocyte migration and increased activity.
  • Reduction of binucleate cells in the trophectoderm.
  • Weakening of the acellular protein layer between cotyledonary and caruncular epithelium.

Contractions

  • Open endometrial crypts
  • Foetal villi have shrunk due to the escape of blood from the foetal side of the placenta when the umbillical cord ruptures.
  • Myometrial contractions aid exsanguination of the placenta.
  • Separation of foetal membranes.
  • Apex of the allantochorionic sac becomes inverted.
  • As the sac is 'rolled' down the uterine horns, foetal villi are drawn out of the crypts.
  • When a large portion becomes detached and inverted, it forms a mass in the maternal pelvis.
    • Stimulates reflex contractions of abdominal muscles.
    • Completes expulsion of the allantochorionic sac.
  • In polytocious species, dehisence and expulsion of foetal membranes are interspersed with births of the young.
    • Only expulsion of the last afterbirth stimulates abdominal contractions.
  • The final stage of allantochorionic expulsion lasts 1 hour (mare) - 6 hours (cow).
  • Domestic animals normally eat the afterbirth.
    • Not the mare or camelids.

Parturition Behaviour

Mare

Stage 1

  • Mammary hypertrophy, waxing of the teats and possible escape of milk from the glands.
  • Patchy sweating behind the elbows and around the flanks.
    • Commences ~4 hours before the birth of the foal and increases as the stage progresses.
  • Yawns
  • No indication of pain.
  • Food is taken readily
  • Respirations are normal
  • Pulse is ~60
  • Body temperature may become slightly subnormal (36.5-37◦C).
  • Restlessness, wanders aimlessly.
  • Tail is frequently raised or held to one side.
  • May swish the tail or slap it against the anus.
  • Kicking of the abdomen
  • Towards the end of this stage:
    • Crouching
    • Straddling of hindlimbs
    • Going down on knees or sternum and rising again
    • Glancing at flank
  • This stage terminates with the rupture of the allantochorionic membrane and the escape of allantoic fluid from the vulva.
    • No visible straining during this period.

Stage 2

  • Abrupt onset, lasts~17 minutes
  • Appearance of the amnion or commencement of forceful straining
    • Not much delay between them, often coincide.
  • Soon after straining begins, the mare goes down.
  • Lies on her side with the limbs extended
    • Generally remains in this position until the foal is born.
  • Transperent blue/white 'water bag' (amnion) visible at the vulva
  • Quickly followed by the appearance in it of a digit.
  • Straining at regular intervals.
    • Each comprises 3/4 powerful expulsive efforts followed by a period of rest.
    • Generally 3 minutes long
  • One forelimb procedes the other by 7-8cm
    • One elbow passes through the pelvic inlet before the other preventing minimal obstruction.
  • Head is usually in the oblique position, but may be transverse with the cheek lying on the limbs.
  • Greates and longest effort is with birth of the head.
  • After expulsion of the foal, the mare may remain on her side exhausted for up to 30 minutes.
  • Umbillical cord is intact when the foal is born.
    • Subsequently ruptures 5-8cm below the belly due to movement of the mare or foal.
  • Foal is usually born within the amnion, which is ruptured by movements of the forelegs.
  • Lower portions of the hindlimbs often remain within the vagina for minutes after the rest of the foal is born.

Stage 3

  • Membranes expelled quickly after the birth of the foal.
  • Usually within 3 hours.
  • Duration of stage 3 is ~30 minutes.
  • Afterbirth is expelled by myometrial contractions with no straining.

Cow

Stage 1

  • Lasts ~6 hours
  • Relaxing of pelvic ligaments.
  • Mammary secretions change from transparent,honey-like to opaque, cellular colostrum.
  • Body temperature subnormal by ~0.6◦C.
  • Parturition will begin 12 hours after complete relaxation of the posterior borders of the sacrosciatic ligaments.
  • Heifers may show signs of abdominal pain for up to 24 hours before the cervix is fully dilated.
  • Occasional straining may occur.
  • Picks at feed, irregular rumination
  • 'Lowing'
  • Kicking of the abdomen
  • Restless, may stand with her back arched and tail raised.
    • May go down and rise again frequently
  • Pulse rate often increased to 80-90.

Stage 2

Stage 3

Ewe

Sow

Stage 1

Stage 2

Stage 3

Bitch

Stage 1

Stage 2

Stage 3

Cat

Stage 1

Stage 2

Stage 3

BACK TO REPRODUCTIVE SYSTEM
BACK TO PARTURITION