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The Next Generation Exam 3 > Initiation of Parturition > Flashcards

Initiation of Parturition Flashcards

1
Q

What triggers the onset of parturition?

A

Fetal stress

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2
Q

How does fetal stress initiate parturition?

A

Maturation of the fetal HPA axis
Small space leads to fetal stress, increasing cortisol levels, leading to a chain of events

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3
Q

How do progesterone levels affect the onset of parturition?

A

Decreased progesterone removed the “block” on uterine contractions

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4
Q

How do estrogen levels affect the onset of parturition?

A

Increased estrogen causes induction of oxytocin receptors, pelvic ligament relaxation, vulvar swelling, and uterus becomes responsive to induction of contractions

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5
Q

Which hormones cause the pelvic ligaments to relax & what other clinical signs would be noticeable?

A

Relaxin, Estrogen
Gluteal muscles sink, tailhead becomes more prominent, sacrosciatic ligament softens

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6
Q

Cortisol levels in the fetus also enhances:

A

surfactant production (leads to lung maturation)

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7
Q

Expansion of the birth canal is caused by:

A

Relaxin, estrogens

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8
Q

Maternal behavior prior to parturition is controlled by:

A

Oxytocin

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9
Q

Which two hormones control milk production in the dam?

A

Prolactin (synthesis) and oxytocin (letdown/ejection)

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10
Q

Initiation of uterine contractions is caused by:

A

PGF, oxytocin

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11
Q

Which hormone is responsible for the termination of pregnancy?

A

PGF

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12
Q

Signs of impending parturition:

A

Mammary enlargement and colostrum production, Enlargement/elongation and laxity of vulva
Pelvic (sacrosciatic) ligament relaxation and softening of the perineum area, isolation, decrease in appetite (off feed)

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13
Q

Gestation lengths of large animals:

A

Camelids/mares: 11-12 months
Cattle: 283 days (~9.5 months)
Sheep: 152 days (~5 months)
Goats: 150 days (~5 months)
Pigs: 114 days (3 mo, 3 weeks, 3 days)

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14
Q

First stage of parturition is initiated by:

A

The fetus

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15
Q

What happens during the first stage of parturition?

A

Relaxation/Dilation of the cervix, uterine contractions commence, fetus adopts birth posture, chorioallantois enters vagina

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16
Q

What are some clinical signs seen during the first stage of parturition?

A

Isolation/off feed, colic signs, tail flagging/raising, vaginal discharge, milk & colostrum production (Wax plugs in mares)

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17
Q

What is the ‘Ferguson Reflex’?

A

Positioning of the fetus so that it triggers a neuroendocrine response in the cervix, resulting in oxytocin synthesis

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18
Q

How does dystocia occur?

A

Failure of Ferguson Reflex to take effect- fetus does not position itself correctly and does not stimulate the neuroendocrine events in the cervix, preventing full oxytocin production

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19
Q

What happens during the second stage of parturition?

A

Cervix is completely dilated
Uterine contractions continue (Ferguson Reflex)
Abdominal contractions begin
Fetus enters birth canal –> causing rupture of chorioallantois
Fetus is expelled

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20
Q

What clinical signs are seen during the second stage of parturition?

A

Water breaks (chorioallantois rupture, lubrication)
Active abdominal contractions
Delivery of fetus

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21
Q

What happens during the third stage of parturition?

A

Placental circulation is lost
Placental dehiscence and separation occurs
Uterine and abdominal contractions continue
Placental expulsion

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22
Q

What clinical signs are observed during the third stage of parturition?

A

Expulsion of the placenta!

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23
Q

If you see a placenta hanging from an animal should you pull it to help them pass it?

A

NO.

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24
Q

How long should stage two (fetal expulsion) last in each species?

A

Camelid: 5-90 min
Bitch: ~6h
Queen: 30-60 min/kitten (2-4h)
Cow: 30-60 min
Ewe: 30-120 min
Mare: 12-30 min
Sow: 150-180 min (20-30 min b/w piglets)

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25
Q

Best methods for predicting parturition in bitches?

A

Twice daily rectal temps, look for transient drop (98-97.5)
Ultrasound for fetal gut motility & renal pelvis
P4 levels can help, but not practical

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26
Q

Best methods for predicting parturition in mares?

A

Milk calcium > 200ppm; foaling in 24-72 hours
Fast decrease in milk pH from slightly alkaline (7.5) to slightly acidic (6.5-6.8); foaling within 24 hours

27
Q

Best methods for predicting parturition in ruminants?

A

Breeding dates/physical changes
Size of fetus (U/S v. palpation)
Calving sensors
Drop in rectal temp by 0.5 degrees F at 24 hours before parturition

28
Q

Other possible (but impractical) tests for predicting parturition in ruminants:

A

blood glucose, blood progesterone, measurement of sacrosciatic ligament relaxation

29
Q

Best methods for predicting parturition in sows?

A

Breeding dates/physical changes
Enlarged mammary glands 1-2 days before farrowing
Restlessness and nesting behavior 12-24 hours prior
Frequent defecation & urination, inc. resp rate
Lie in lateral recumbency last 15-60 min

30
Q

What is dystocia?

A

Anything that impedes the process of parturition (can be maternal or fetal causes)

31
Q

General maternal causes of abortion include:

A

Failure of expulsive forces
Obstruction of the birth canal
Lack of cervical dilation
Uterine torsion

32
Q

What are the uterine causes leading to lack of expulsive forces?

A

Primary & secondary uterine inertia
Uterine damage/rupture

33
Q

What is primary uterine inertia?

A

Myometrial defects (overstretching, degeneration, infection, heredity)- Hydrops
Biochemical deficiencies (milk fever/hypocalcemia; pregnancy toxemia/ketosis)
Environmental disturbance (heat/cold stress)

34
Q

What is secondary uterine inertia?

A

Consequence of another cause of dystocia (exhaustion); i.e. running out of calcium stores

35
Q

What is the most common cause of uterine related dystocias?

A

Secondary uterine inertia

36
Q

What are abdominal causes leading to lack of expulsive forces?

A

Inability to strain: age, prepubic tendon rupture, abdominal herniation

37
Q

What things can lead to a “bony” obstruction of the birth canal?

A

Bony pelvis: fracture, breed, diet, immaturity, neoplasia, disease

38
Q

What is the minimum area the pelvic inlet should be for parturition?

A

150 cm squared

39
Q

What are some soft tissue abnormalities of the vulva leading to obstruction of the birth canal?

A

congenital defects, fibrosis, immaturity (heifers)
May require episiotomy or C-section

40
Q

What are some soft tissue abnormalities of the vagina leading to obstruction of the birth canal?

A

congenital defect, fibrosis, prolapse, neoplasia, perivaginal abscess, hymen

41
Q

What are some soft tissue abnormalities of the cervix leading to obstruction of the birth canal?

A

Congenital defect, fibrosis, failure to dilate

42
Q

What are some soft tissue abnormalities of the uterus leading to obstruction of the birth canal?

A

Torsion, deviation, herniation, adhesion, stenosis

43
Q

What causes lack of cervical dilation? How do we manage these causes?

A

Ringwomb (sheep) –> CULL
Lack of stimulation (malpositioning of the fetus; prolapse–> manual stimulation)
Adhesions/fibrosis (previous traumas, cull female)

44
Q

What is Ringwomb?

A

Heritable condition in sheep
Idiopathic failure of the cervix to dilate
C-section required; cull ewe & do not breed offspring

45
Q

How do you address a uterine torsion with a closed cervix?

A

C-section (usually can untwist after delivery)
Rolling or planking cow

46
Q

How do you address uterine torsion with an open cervix?

A

Detorsion rod
If detorsion rod fails: C-section

47
Q

What are fetal causes of dystocia?

A

Hormone deficiency (failure to initiate birth w/ ACTH/Cortisol; immaturity)
Feto-maternal disproportion
Fetal maldisposition
Fetal death

48
Q

What are examples of causes of fetomaternal maldisproportion?

A

Sire genetics
IVF/Cloned calves: large offspring syndrome
Fetal monsters/anomalies: conjoined twins, schistosomus, ankyloses, hydrocephaly

49
Q

Why does fetal death result in dystocia?

A

Dead fetus cannot initiate parturition- indicator for inducing!

50
Q

What clinical signs might be seen if a fetus is dead?

A

Mummy/macerated fetus
Black vulvar discharge in bitch
Premature placental separation in mares (Red bag delivery)

51
Q

Reasons for induction of parturition?

A

Mismating (should be done early)
Prolonged gestation (be 110% SURE!)
Edema of mammary gland (dairy)
Medical necessity (pregnancy toxemia, hydrops)
If likelihood of intervention is high (large fetus, young heifer)
Convenience: planned assistance/attendance

52
Q

Golden rule for induction of parturition:

A

Don’t induce!
Let nature run its course

53
Q

Induction of parturition in cattle:

A

20-40mg Dexmethasone if beyond 270 days (Calve 24-72 hours; avg 48)
Tighten interval with prostaglandin (Lutalyse, 25mg - 24-48h, abg 36)
Survival good if within 1-2 weeks of due date

54
Q

Common sequelae of induction of parturition in cattle:

A

Retained placenta
Oxytocin to expel

55
Q

Induction of parturition in sheep:

A

15-20mg Dexamethasone if beyond 137 days (lamb within 36-48 hours)
+/- Prostaglandin
Dinoprost (Lutalyse), 5-10mg; Cloprostenol (Estrumate), 75-100 micrograms/45kg
Survival good if within 1 week of due date

56
Q

Induction of parturition in goats?

A

CL DEPENDENT!
Dinoprost/Lutalyse 5-10mg
Cloprostenol/Estrumate 75 micrograms/45 kg
At least 144 days gestation, kid within 30-36 hours
Survival good if within 1 week of due date

57
Q

If there are concerns for prematurity in goats, before inducing parturition, what should you do?

A

Give 10-20mg Dexmethasone 6-12 hours before you induce

58
Q

Induction of parturition in pigs?

A

CL DEPENDENT!
10-20mg PGF2a (Lutalyse) at least 112-113 days in gestation (farrow in 18-36 hours)
Can give 5-30 IU oxytocin 20 hours AFTER Lutalyse to inc. % to farrow in subsequent 6 hours

59
Q

What is the stipulation with giving oxytocin IU to sows/gilts for induction?

A

Higher dose more effective for synchronizing farrowing; BUT
lower doses recommended due to risk of fatigue

60
Q

Induction of parturition in mares?

A

Oxytocin IV or IM
10 IU IV q15-30min by slow drip IV
May need 4-6 doses
Min 2 cm dilation of cervix
May then inc. to 20 IU; can go up to 40-60 IU but watch for colic signs

61
Q

When would be the right time to induce parturition in mares?

A

ONLY if the mare’s life is in danger

62
Q

Induction of parturition in bitches/queens?

A

Difficult, fetal death can result prior to parturition
P4 receptor blocker (Aglepristone) shown effective
Not available in US; no agent to induce queens

63
Q

How would you determine if an animal is truly overdue?

A

Know gestation lengths!
Expectancy dates
Owner must be 100% sure of breeding date (be wary, use U/S)

The Next Generation Exam 3 (4 decks)

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