Parturition Module
AnS 536
Spring 2015

We need to be able to picture what is
going on on the inside by what we see on
the outside…

Do not intervene the process unless
absolutely necessary

Humans


Cattle


Gestation length: 283 days
Swine


Gestation length: 280 days
Gestation length: 114 days
During Gestation:

Progesterone levels remain high



Humans


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Keeps uterus in a stage of inactivity (“dormant”)
Maintains pregnancy
Human chorionic gonadotropin (hCG) responsible for maintaining
corpus luteum (CL)
CL produces progesterone
Third Trimester = “late gestation”


Uterus becomes more excitable
Hormone levels change
Before Parturition, Focus on
Environment
Keep
the pen clean, dry and well ventilated
Swine: The farrowing pen temperature should be
approximately 20 ̊C and the piglets’ nest area, 30
to 32 ̊C
 Canadian
studies in 2002 reported a 20% reduction in
piglet mortality when a second heat lamp behind the
sow provided a zone at 31 ̊C during farrowing.
Cleanliness
of stall and perineal region of mother
is KEY to keeping neonate healthy
 Prevents
sepsis, umbilical infection
 If not, increased exposure to any fecal- orally
transmitted pathogens= increase in mortality
Clean perineal region vs. Dirty
Clean environment vs. Dirty
Hormonal Mechanisms Controlling
Parturition

In general, these physiological events occur
during parturition:
 Dilation
of cervix
 Contractions of the uterus
 Progesterone levels decrease
 CL and placenta increase production of relaxin
Hormonal Mechanisms Controlling
Parturition

Cattle
 Nearing


Fetal adrenal gland matures and fetal cortisol levels increase
dramatically initiating the cascade leading to parturition
Estradiol increases


Contraction of the uterus
Oxytocin production


Stimulates vaginal and cervical mucous secretion
Prostaglandin increases


term
Caused by increased pressure on the cervix, further increases
contractions
Relaxin production

Relaxes pelvic ligaments
Hormonal Mechanisms Controlling
Parturition

Cattle cont…
 Muscular

contractions continue to increase
Pressure causes membrane rupture
 Fetus
begins to move into the birth canal
 Fetus becomes hypoxic
Increases fetal movement
 Increased muscle contraction and expulsion of
fetus

Hormonal Mechanisms
Controlling Parturition

Sows…
 Parturition
is initiated by increased cortisol levels,
which also stimulate release of prostaglandin (PG) F2α
from the uterus.
 PGF2α causes luteolysis of the corpora lutea and
release of relaxin.
 Oxytocin is released from the pituitary gland, which
causes uterine contractions and onset of labor.
Process of Parturition

Three separate stages
 Stage
1: Cervical dilation
 Stage 2: Delivery of the fetus
 Stage 3: Expulsion of the placenta
Process of Parturition


Stage I –
Uterine contractions:

Myometrial ischemia: decreased blood flow to myometrium of
uterus


Causes release of potassium, bradykinin, histamin, serotonin
Cervical dilation

Cervical opening expands to a maximum of 10 cm
 Longest stage of labor

Lasting a few hours up to 24 hours
 Cervix dilates with increased pressure from the fetus

Normal presentation – fetal head applies pressure

Fetal head is the largest circumference among the body besides
shoulders

Abnormal presentation – pressure on cervix may not be as great
to promote maximum cervical dilation needed for fetal passagecan lead to dystocia
Process of Parturition

Stage II – Delivery of the fetus
 Occurs
once cervical dilation is complete
 Fetus is able to pass through cervix and vagina
 Fetal passage triggers stretch receptors in the vagina
activating a neural reflex


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Triggering contraction of the abdominal wall in synchrony
with uterine contractions
Increased force pushes fetus through birth canal
Additional voluntary force via abdominal muscle
 Complete


passage through the canal
Fetus is still attached via umbilical cord
Umbilical cord is severed after complete delivery
 https://www.youtube.com/watch?v=lN4DTps8Iuo
Sows or other litter-bearing species..
 Piglets are usually delivered at frequent
intervals (10–15 min; 5–45 min range).
 Uterine horn evacuation is random.
 https://www.youtube.com/watch?v=iN4lKC
iOGVE

Human Pelvis
Human Fetal Presentations
Cow Pelvis
Normal Calf Presentation
Abnormal Calf Positions
Process of Parturition

Stage III – Expulsion of the Placenta
 Occurs

shortly after delivery
Varies among species
 Second
wave of uterine contractions occur
Separate the placenta from the uterus
 Expelled through the vagina
 Uterine contractions constrict blood vessels
supplying site of placental attachement


Prevent bleeding
 Shortest
stage of delivery
Dystocia

Noted when difficult, prolonged, or
abnormal parturition occurs
 Physical
signs of dystocia:
Cattle: anything other than two front feet showing,
ex; only one foot, two rear feet
 Lots of blood or meconium in amniotic fluid or on
neonate
 Neonate has it’s tongue sticking out


It is lacking muscle tone, is a color other than pink
Swine..
 Incidence of dystocia is low (1–2%)
 According to the Journal of Swine Health
and Production: Obstetrical intervention is
indicated if

 30
to 45 minutes have passed since the last
piglet was born
 if 24 hours have passed since the first signs
of impending parturition were observed and
no piglets have been born
 if the sow is not able to farrow despite strong
uterine contractions.
Dystocia

Contributing factors:
 Presentation
of fetus greatly affects the degree of
dystocia

Breech births, etc.
 Large
birth weight
 Small maternal pelvic measurements
 First parity mothers

First-calf beef heifers have 16.7% dystocia vs 2.7% seen in
cows
Dystocia

Contributing factors cont…
 Fetal

abnormalities
Genetic mutations
 Maternal

Seen in recipient dams carrying cloned fetuses
 Maternal



failure to recognize onset of parturition
health and/or body condition score
Affects the stress and health of fetus
Labor may be untimely, too early
Avoiding fetal mortality:
 Timely
recognition of problems
 Proper assistance in labor process
As with all polytocous species, uterine
inertia accounts for most dystocia in swine
 Other causes: fetal malposition,
obstruction of the birth canal, deviation of
the uterus, fetopelvic disproportion, and
maternal excitement.
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Managing Dystocia
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Forceps assisted vaginal delivery (humans)
Vacuum assisted vaginal delivery (humans)
Calf jack to pull calf out of birth canal
Cesarean section
 Performed often in humans
 Compromised delivery
 Mothers can opt for c-sections
 Livestock
 Often used as a last resort


Cause scarring in the uterus


Incurred veterinary cost is high
Difficult for the animal to breed back
Drugs such as oxytocin, prostaglandin, and corticoids are
administered
Force of Assistance

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


Pulling force should not exceed 150 pounds for Holstein and 75
pounds for Jersey
 Assist in dilation prior to pulling (5 minutes)
 Use appropriate lubricant (not soap and water)
 Watch your time and assess the calf condition
 One person pulls with ~100-150 pounds of force
 Two people pull with ~300 pounds of force
 600 pounds of force will fracture femur
 Calf jack can generate 1500-2000 pounds of force
Apply minimal force during contractions pull calf so head is pushing
on the cervix between contractions to speed up cervical dilation
Pull calf straight out until head delivered
Deliver shoulders and body at 30 to 400 angle
Stop assistance after last rib and allow dam to expel fetus

Assistance prior to full cervical dilation or the
use of excessive force is associated with a high
incidence of rib fractures (~40%) and a lower
incidence of front leg and vertebral fractures
(~10%)
Calf Jack and OB Chain Use

https://www.youtube.com/watch?v=_HyAp
xVijCU calf jack

https://www.youtube.com/watch?v=9aIcnL
BXdL0 OB chain placement
Piglet Dystocia Management
Managing Dystocia

Litter bearing animals
 First
sleeve and physically check
 First of several fetuses can be stuck in the birth canal


Can compromise the rest of the litter
Survivability declines with added time of stress
 Canine

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Differ from large animal and humans
Small animals are put under general anesthesia

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and feline C-sections
Better restraint of animal, fastest and safest way to deliver
Cattle and humans – epidural anesthesia
Dystocia Impacts:

Calves:

severe acidosis compared to a normal, unassisted birth
Depressed central nervous system
Decreased physical activity and reduced shivering
results in more heat loss and hypothermia.
Suckling and the consumption of colostrum may not
occur or be severely reduced
3.2% of unassisted calves (score of 1) were stillborn
compared with 8.4% of calves stillborn with a slight
assistance with no jack (score of 2), and 37.2% of calves
stillborn with use of jack (score of 3)
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Affect on COWS:
 calving
dystocia reduces milk production,
reproductive performance and cow survival
and can consequently reduce farm profitability

Swine:
A
2013 study showed that: Sows that had a
long duration of farrowing (>300 minutes)
have higher repeat breeding rate (pregnant
vs. not pregnant at first insemination after
weaning
Induction of Parturition

Protocols depend upon:
 Length
of gestation
 Size and development of fetus

Cattle
 Long
acting corticosteroids
Lead to parturition in 2-26 days
 Wide time range can be disadvantageous
 May have detrimental effect on dam influencing
preexisting health condition
 Fetal membrane retention is low

Induction of Parturition

Short acting corticosteroids
 Frequently
used, very effective
 Injected within 2 weeks of due date
 Parturition usually occurs in 24-72 hours
 Colostral immunoglobulins are normal
 Influence fetal lung development
 Retained fetal membranes are high

Also related to gestational age of calf: younger calf
= high incidence of retained membranes
Induction of Parturition

Prostaglandins
 Effective
method
 No advantage over corticosteroids

Estrogens
 Old
method
 Poor efficacy
Induction of Parturition

Combinations
 Goal:
reducing rate of retained placentas,
avoiding induction failures and calf mortality
 Short acting corticosteroids + estrogen
 Long acting corticosteroids + short acting
corticosteroids or prostaglandins
 Short acting corticosteroids + prostaglandin
Multiple Pregnancies

Greater demand on the mother and
increased risk on fetus
 Nutritional
demand is higher
 Iron and folate needs increase
 Anemia is reported more frequently
 Morbidity and mortality of twins is higher
compared to singleton pregnancies

Increased risk of delivering prematurely
Multiple Pregnancies

Mode of delivery can be more difficult
 Plays
major role in infant outcome, especially
second born twins
Cesarian-cesarian
 Vaginal-vaginal
 Vaginal-cesarian

 Vaginal-cesarian
mode is most detrimental to
second born twin
 Presentation and birth weight of twins greatly
affects mode of delivery and outcome of infant
Multiple Pregnancies

Congenital defects
 Neural
tube defects
 Cardiac abnormalities
 Bowel atresia

Other problems:
 Conjoined
twins
 Twin reversed arterial perfusion sequence
 Poor fetal growth
 Placentation
 Amniocity
 Freemartin (cattle)
Multiple Pregnancies

Animals designed to carry singleton pregnancies:
 Humans
 Cows
 Mares

Animals designed to carry multiple pregnancies:
 Sows
 Ewes
 Queens
 Bitches
 Rodents
Management of Calving

Group Calving Pros:

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Saves labor and saves money
Herd animals do not like to be isolated
Presence of other cows calving stimulates other cows
Group Calving Cons:

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Changing social dynamics
Biosecurity: transfer of fecal-oral pathogens
Herd animals when calving prefer to isolate themselves and
can’t
Other cows can get maternally aggressive to other calves that
are not theirs


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Calves can get injured and stepped on by other interested cows
More cows together= less individual attention especially with
dystocia
If individual attention is needed, harder to safely assist
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Individual Calving Pros:
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Can monitor cows individually for issues and feed intake
Minimize biosecurity issues
 Only one cows pathogen, only one to two calves exposed
No identification issues
Safer for cow and workers if assistance is needed
Safer environment for calf after birth
Individual Calving Cons:


More cost, more labor
Isolation is stressful for herd animals- especially heifers
Management of Farrowing

Stalls/crates:
 Con:
sows are completely restrained, thus
less exercise for sows
 Pros: stall/crate can protect pigs better,
reduce labor in cleaning/handling, economize
utilization of the space, assist sows/pigs
easily, and eliminate or reduce the use of
bedding

Pens:

Con: requires more cleaning labor, more
space, and sows must be restrained for any
physical treatment
 Pros: but they allow more sow movement &
pens can be converted into nursery or
growing pens