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 Gestation length: 280 days

Cattle Gestation length: 283 days

Swine Gestation length: 114 days

During Gestation: Progesterone levels remain high

Keeps uterus in a stage of inactivity (“dormant”) Maintains pregnancy

Humans 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 C̊

Canadian studies in 2002 reported a 20% reduction in piglet mortality when a second heat lamp behind the sow provided a zone at 31 C̊ 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 cervixContractions of the uterusProgesterone levels decreaseCL and placenta increase production of relaxin

Hormonal Mechanisms Controlling Parturition Cattle

Nearing term Pressure within the uterus causes stress on the fetus,

stimulating the release of fetal cortisol Estradiol increases

Stimulates vaginal and cervical mucous secretion Prostaglandin increases

Contraction of the uterus Oxytocin production

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 canalFetus 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 stagesStage 1: Cervical dilationStage 2: Delivery of the fetusStage 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 passage- can 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 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=iN4lKCiOGVE

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 occursPhysical 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 failure to recognize onset of parturition Seen in recipient dams carrying cloned fetuses

Maternal 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.

Managing Dystocia 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

Incurred veterinary cost is high Cause scarring in the uterus

Difficult for the animal to breed back Drugs such as oxytocin, prostaglandin, and corticoids are

administered

Force of Assistance 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=_HyApxVijCU calf jack

https://www.youtube.com/watch?v=9aIcnLBXdL0 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 and feline C-sections Differ from large animal and humans Small animals are put under general anesthesia

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)

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 gestationSize and development of fetus

CattleLong 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 corticosteroidsFrequently used, very effective Injected within 2 weeks of due dateParturition usually occurs in 24-72 hoursColostral immunoglobulins are normal Influence fetal lung developmentRetained fetal membranes are high

Also related to gestational age of calf: younger calf = high incidence of retained membranes

Induction of Parturition

ProstaglandinsEffective methodNo advantage over corticosteroids

EstrogensOld methodPoor efficacy

Induction of Parturition

CombinationsGoal: reducing rate of retained placentas,

avoiding induction failures and calf mortalityShort acting corticosteroids + estrogenLong acting corticosteroids + short acting

corticosteroids or prostaglandinsShort acting corticosteroids + prostaglandin

Multiple Pregnancies

Greater demand on the mother and increased risk on fetusNutritional demand is higher Iron and folate needs increaseAnemia is reported more frequentlyMorbidity and mortality of twins is higher

compared to singleton pregnancies Increased risk of delivering prematurely

Multiple Pregnancies

Mode of delivery can be more difficultPlays 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: Saves labor and saves money Herd animals do not like to be isolated Presence of other cows calving stimulates other cows

Group Calving Cons: 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 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

Individual Calving Pros: 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