32, 33, 34 - phys and induction of partirution Flashcards

1
Q

what controls and influences gestational length?

A

controlled genetically

influenced by feto-maternal size ratio

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2
Q

cow gestation length?

variation?

A

280

+/- 14 d
longer in Bos indicus

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3
Q

mare gestation length?

variation?

A

340 days

320–360

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4
Q

sow gestation length?

A

114 d

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5
Q

doe and ewe gestation length?

A

150 days average for both

dow: 148-1555
ewe: 145-150

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6
Q

bitch gestation length and timing?

A

65 d from LH surge
+/- 1

also: 57 +/- 2 from cytological diestrus 1

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7
Q

queen gestation length and timing?

A

63 days from ovulation

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8
Q

hembra gestation length and timing?

variation?

A

334 d from breeding

320-360 variation

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9
Q

pregnancy is complex interplay btwn what entities?

A

dam, endometrium, myometrium
ovaries with CLs on them

placenta
fetus, fetal membranes

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10
Q

what hormone controls endometrial secretions in the bitch?

A

p4

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11
Q

what hormone maintains preg?

A

p4

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12
Q

how does p4 maintain pregnancy?

what mechanisms in the bitch?

A

endometrial gland secretions
uterine circulation
myometrial quiescence
cervical closure

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13
Q

what is a source of p4 in all species?

A

CL

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14
Q

the placenta is an additional source of p4 in what species?

A

mare
ewe
queen

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15
Q

what additional source of p4 is suspected in cattle?

A

adrenal gland

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16
Q

what must occur in the fetus and dam in order for parturition to occur?

A

fetal maturation - prep for extra uterine life
induction of lactation
cervical ripening - prep for passage of fetus
pelvic lig relaxation
myometrial contractility - evacuation of uterine contents

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17
Q

what is basic structure of myometrium?

A

smooth muscle structure

actin and myosin muscle fibers - slide across each other to contract

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18
Q

what enzyme is required for myometrial contraction?

what is it activated by?

A

MLC kinase

activated by calmodulin

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19
Q

what activates calmodulin in the myometrial muscle cells?

therefore, what is required to initiate the cascade that leads to myometrial contraction?

A

ionized calcium

influx of ionized Ca into the cells

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20
Q

what contributes to the Ca levels in the myometrial cells?

A

sarcoplasmic reticulum

extra cellular fluid compartment

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21
Q

what governs the influx of Ca into myometrial cells?

A

CAPS

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22
Q

what is the structure of CAPS?

what is the function of each component?

A

CAPS are made of 3 fraction associated proteins

2 are receptors: 1 for PG and 1 for oxytocin
3rd is formation of gap junctions to allow passage of Ca through junctions

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23
Q

when PG and oxy bind to the CAPS receptors, what do they induce?

A

the formation of more gap junctions and further Ca influx

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24
Q

describe the interaction btwn oxy and PG.

which is a better ecbolic agent?

A

oxy drives PG release

PG is stronger ecbolic agent

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25
Q

how is the myometrium prevented from contracting during pregnancy?

A

the contraction cascade is suppressed

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26
Q

what is the “rate limiting step” in a normal pregnancy, to begin the parturition cascade?

A

fetal hypoxia

b/c the fetus needs outgrow the supply capacity of the placenta

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27
Q

fetal hypoxemia triggers what hormonal cascade in the fetus, which leads to parturition?

A

hypoxia induces sec of CRH from hypothalamus

stim fetal pituitary to sec ACTH

stim fetal adrenal glands to sec cortisol

stim sec of PG in the placenta

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28
Q

in general, most end products of cascades are regulated by their own negative feedback mechanism.

in the fetus, at the time of parturition, this is suppressed by 3 mechanisms.

what are they?

A
  1. cortisol being released by fetus is highly protein bound
  2. some cortisol is inactivated to cortisone, which suppresses the cortisol receptor at the level of the pituitary gland, so cortisol cannot feedback and cause inhibition
  3. PG does not reach maternal circulation - it remains in the feto placental compartment, where it is neutralized by PG dehydrogenase
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29
Q

t/f

neither PG nor cortisol leave the feto-placental compartment to enter the maternal circulation at the time of parturition

A

true

both remain in the feto-placental compartmenet

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30
Q

what is the action of PG in the placenta?

A

PG upregulates the enzymes P450 and c17, which is responsible for the early conversion of early steroids to late steroids => p4 steroids to androgenic steroids

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31
Q

what is the role of fetal cortisol in the hormonal cascade at initiation of parturition?

A

induce enzymes that convert androgens into estrogens

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32
Q

after e2 prod inc, as a result of the fetal hormonal cascade, where does it go and what does it do?

A

e2 crosses the placenta into maternal circulation

induces the formation of CAPS in myometrial cells -> to prepare them for contraction ability

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33
Q

for species with the placental source of p4, what hormonal changes occur at initiation of parturition?

A

pathway changes from p4 production to e2 production

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34
Q

for animals that rely on the CL for p4 at the end of the pregnancy, what triggers luteolysis to end the pregnancy?

A

sec of oxytocin => stim sec of PG => luteolysis

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35
Q

where is oxy that lyses the CL at the end of pregnancy sec from?

A

from the placenta or the CL itself

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36
Q

where is PG sec from, after stimulation by oxy?

A

the endometrium

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37
Q

what hormone causes ripening or softening of the cervix?

A

relaxin

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38
Q

what is the mechanism of relaxin?

A

dissociation of collagen disuphide bonds => dissociation of fibers => cervix opens

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39
Q

what is the origin of relaxin?

A

placenta or CL

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40
Q

in addition to relaxin, what other molecules contribute to softening of the cervix?

A

metalloproteinases

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41
Q

what molecule is selectively up regulated in the cervical muscle cells to promote cervical softening?

A

cAMP

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42
Q

what cell influxes into the cervix?

what cytokine stimulates this movement?

result?

A

NTs influx into cervix under the stimulation of Interleukin 8

degranulate -> sec inflammatory mediators -> dec uptake of Ca into myometrial cells -> promotes relaxation

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43
Q

what happens to conc of Ca in myometrial cells during softening of cervix?

A

dec

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44
Q

what effect does e2 have on cervix?

A

softening -> opening

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45
Q

what stimulates the transition of the allanto-chorion into the cervix?

A

the inc pressure in the myometrium d/t contraction

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46
Q

what mechanical force helps push the cervix open as it ripens?

A

the allanto-chorion pushing on the cervix forces it to open

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47
Q

what stimulates stage 2 of labor?

A

the onset of abdominal pressure

subsequent the neuro endocrine reflex - Ferguson’s reflex

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48
Q

what is Ferguson’s reflex?

A

stretch receptors in the cervix and cranial vagina are activated

connect in posterior pituitary gland to oxy producing neurons loc in hypothalamus

stim sec of oxy -> further contraction

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49
Q

in response to pelvic filling, what voluntary action must occur?

A

mare must abdominal press

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50
Q

t/f

you can see uterine contractions from outside the body

A

false

you see abdominal contractions, NOT uterine contractions

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51
Q

what is stage 3?

A

expulsion of fetal membranes

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52
Q

what species expels a whole placenta rather than fetal membranes?

A

bitch

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53
Q

what is involved in separation of fetal membranes from the endometrium?

A
proteolytic enzymes 
leukocyte enzymes
oxytocin
PGs
mechanical pull
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54
Q

what does the presentation of the fetus describe?

A

longitudinal axes of dam and fetus

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55
Q

how can a fetus appear if in a longitudinal presentation?

A

cranial or caudal longitudinal - axis of fetus parallel to axis of dam

head or butt facing out

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56
Q

what is a transverse presentation?

A

ventral if legs/belly first

dorsal if spine first

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57
Q

what does the position of fetus describe?

examples?

A

the portion of the maternal pelvis against which fetal spine lies

dorso-sacral
dorso-pelvic
dorso-ileal (Left or Right)

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58
Q

MC position of fetus at time of parturition?

A

dorso-sacral -> spine directed against sacrum of dam

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59
Q

what does posture of fetus describe?

what is MC / proper posture?

A

the angulation / flexion of head, neck and presenting limbs

head and forelimbs should be extended in most animals with both front limbs extended

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60
Q

what are sings of pre partum cow indicating she will calve soon?

what hormones is she under the influence of?

A
last week: vulva swells and lengthens
48-24 hours: cervical musus
24 h: tone of tail is poor
udder development 
pelvic ligg relaxation 

e2

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61
Q

when does the udder develop in the heifer?

cow?

A

heifer - as early as 4 mos in heifers

cow - 2-4 weeks before parturition

62
Q

what is the appearance of colostrum pre partum?

A

thick, yellow, turbid

63
Q

first stage of parturition - signs in a cow?

how long?

A

dec appetite
restlessness and separation

lasts 6-12 hours or up to 24 in heifers

64
Q

MC time of day for calf delivery?

A

night

65
Q

how does rumen fill affect calving?

A

rumen fill may delay calving b/c it delays the onset of active parturition

66
Q

what happens during 2nd stage parturition in cows?

A

water breaks - rupture allanto chorion

67
Q

what is the presentation and position and posture of the fetus at 2nd stage labor?

A

longitudinal, cr and dorsosacral

head and neck extended

muzzle at fetlocks

68
Q

what is the widest diameter of the pelvis?

and of the calf?

A

diagonal across the pelvis

at the trochanters on the calf

69
Q

how much force required to deliver a calf?

what % from abdominal press vs myometrial contractions?

A

70 kg

40% from myometrial contractions
60% from abdominal press

70
Q

how long after parturition are fetal membranes expelled in the cow?

A

w/in 8 hours

71
Q

what must occur for normal passage of fetal membranes?

A

the membranes must be mature
villi shrink and maternal crypts dilate to show separation

uterine contractions help with delivery
weight of fetal membranes hanging from birth canal aids in expulsion

72
Q

indications to induce parturition?

A

severe udder edema - risk of suspensory apparatus of udder breaking

vaginal prolapse - need to remove sutures for birth

abnormal pregnancy
elective / c section

supervised calving if suspected issue

73
Q

minimum gestation of cow to induce parturition?

A

265 days

74
Q

what drugs used to induce parturition in cow?

A

dexamethasone

PgF2a

75
Q

fxn of dex in parturition induction in cow?

A

crosses placenta into fetal compartment -> induces endocrine cascade for labor

also: induces fetal lung maturation via inc surfactant production for c section

76
Q

even for a c section, it is necessary to induce parturition in the cow medically.

why?

A

to ensure the calf if mature

77
Q

what is the schedule of injections for a planned c section in the cow?

A

20 mg dex
12 hrs later: 20 mg dex and 25 mg PgF
labor 36 hours after initial dex injection

c sectino 30 h after initial dex injection

78
Q

when parturition is induced in the cow, what % likely to have retained fetal membranes?

significance?

A

80%

usually resolves and no consequences

79
Q

how does induction of parturition affect colostrum and passive transfer capability of dam in the cow?

A

it does not - this occurs normally

80
Q

in the equine, what is the mechanism of action of fescue intoxication and interference with parturition?

A

px the rise in progestagens

81
Q

late in gestation, what maintains pregnancy in the mare?

source?

A

5a pregnanes

the precursor is sec from fetal adrenal and converted by the placenta in the 5a pregnanes

82
Q

what is the change in hormone profile at time of parturition in the mare that induces mammary development?

A

inc in p4

dec in e2

83
Q

what action of fescue intoxication leads to agalactia?

A

suppress prolactin sec

84
Q

what is waxing in the mare?

A

colostrum production -> see milk accumulate at tips of teats

85
Q

when does the mare begin milk prod?

A

when oxy levels inc and myometrial contractions begin

86
Q

what does waxing in the mare indicate?

A

parturition is eminent

87
Q

what is a very specific parameter that is easy to measure and means that the mare will go into labor very soon?

A

high Ca conc in milk
abrupt change

she will foal w/in 2 days

88
Q

what are physical signs of parturition nearing you can see externally on the mare?

A

vulva becomes very looooong

pelvic ligaments become lax

89
Q

what is the appearance of the teats in the mare when she is near foaling?

A

flat teat cistern will become cylindrical

90
Q

what is best method / sampling protocol for tracking Ca conc in mare milk to predict foaling?

what levels of Ca indicate foaling?

A
  • begin sampling 10-14 d prior to expected foaling
  • test 2x daily when Ca reaches 125 ppm
  • 50% of mares foal w/in 24 hours of Ca reaching 200 ppm
  • 300-500 ppm Ca means she will foal anytime
91
Q

when Ca levels are below ____ ppm, foaling is RARE

A

200

92
Q

MC time of day for mare foaling?

A

night

93
Q

signs mare will foal that night?

A

inconspicuous

sweating, restless
running milk
colic

94
Q

t/f

mares can “hold off” labor, and will do so if they are nervous or are being watched

A

true

give them space and quiet and to NOT bother them

95
Q

what stage of labor in the mare does the foal assume his appropriate birthing presentation/position/posture?

A

during the first stage of labor

96
Q

2nd stage of labor in foals?

how long until birth?

A

water breaks
very forceful, abdominal contractions

birth in 30 mins

97
Q

typical position of mare during foaling?

A

lateral recumbence

98
Q

in order to Px the foal from suffering and proceed with a normal birth, what membranes must rupture?

A

allanto chorion

if this does not rupture - if the water does not break - then that indicates the foal is suffocating

99
Q

if the allanto chorion does not rupture appropriately, what should you do?

A

tear it open

100
Q

t/f

the foal passes thru the birth canal w/in the allanto chorion

A

false

foal is in the amnion
the allanto chorion ruptures first

101
Q

what occurs during the transition from 1st stage labor to 2nd stage labor?

this is often surpassed or not allowed to happen when intervention occurs, and predisposes mare to tearing

A

stretching and dilation of the cervix

prone to cervical tearing if this is not allowed to happen - just b/c you can intervene immediately does NOT mean you should

102
Q

t/f

you should tear the umbilical cord immediately after birth

A

false - placenta is still functional just after delivery

let the blood in it go into the fetus - allow placental circulation to continue as long as it naturally does - do not deprive the fetus of that last bit of oxygen, before the amnion ruptures

may take 3 seconds or 30 mins for it to tear on its own and that is okay

103
Q

how long should the 3rd stage of labor last in the mare?

at what point is it an emergency if the mare does not expel her membranes?

A

less than 60 minutes

emergency after 4 hours

104
Q

once expelled, which surface of the membranes are facing you?

A

the allantoic side is facing you and the chorion is the inner surface

the membranes get turned inside out with tension during parturition

105
Q

what is minimum gestation length of mare?

A

320 days

106
Q

t/f

it is relatively simple to determine fetal maturity in mare

A

false

why induction of parturition should be considered carefully and NOT rushed into and avoided if possible

107
Q

what specific gravity should colostrum have to indicate it is mature?

A

1050 or higher

108
Q

indications for parturition induction in the mare?

A

deformed pelvis, fracture, colic, etc

premature colostrum leakage

Hx of NI

109
Q

how to induce fetal maturation in pregnant mare?

how long does it take?

A

dex

3 days

110
Q

parturition induction drugs in mare?

how soon do they take effect?

A

mare
oxy => 10-20 units

should see 1st stage of labor w/in 20 mins
foal should be delivered w/in 60 mins

111
Q

most reliable indication of parturition in small ruminants?

A

mammary gland development

behavior: separation from rest of the flock

112
Q

what are timing of each of the 3 stages of labor in small ruminants?

A

1: separation from flock, 6-12 hours
2: Cr or Cd - 30-60 mins per lamb
3: 30-120 mins

113
Q

indications for induction of parturition in small ruminants?

A

preg tox
vaginal prolapse
caprine arthritis encephalitis virus - observe birth to Px suckling and dec transmission

114
Q

drugs to induce parturition in ewe?

A

16 mg dex

birth in 48 hrs

115
Q

drug to induce parturition in doe?

A

16 mg dex
10 mg PgF2a

kid in 30-35 hours

116
Q

why is dex important for induction of parturition in small ruminants?

A

induces fetal maturation of lungs

117
Q

sow signs of parturition nearing?

A

7-10 days: mammary enlargement
3-4 days: vulva swollen
24 hrs: milk expressed from mammary gland

anorexia, restless, build nest (environment dependent)

118
Q

length of each stage of labor in sow?

A

1: 2-12 hours
2: 1-4 hours
3: fetal mem expelled during 2nd stage in between pig births and/or at the end

119
Q

how much time is appropriate in btwn delivery of successive piglets?

A

15 mins avg

120
Q

what is earliest a sow can be induced to farrow?

A

72 hours prior to due date

121
Q

what drugs to induce parturition in sow?

when given relative to each other?

A

PgF: 10 mg

oxy: 5-30 units

give oxy 20-24 hrs AFTER PgF administration

122
Q

t/f

dex is not necessary for piglet maturation

A

true

123
Q

what are reliable signs of impending whelping in the bitch?

A

core temp drop by 2*, means birth in 12 hours

124
Q

what hormone can be measured to indicate birth w/in 24 hours is likely in bitch?

A

p4

should be less than 2 ng/mL

125
Q

first stage of parturition in bitch?

sign and timing?

A

nesting behavior

6-24 hours before birth

126
Q

2nd stage labor in bitch?

A

0.5-3 hours

green/black vulvar discharge

127
Q

what is the green / black vulvar discharge that occurs in 2nd stage parturition of bitch?

A

marginal hematomas

it is utero-verdin that is secreted

128
Q

3rd stage of labor in bitch?

A

green / black parturient discharge

birth of pups and expel fetal membranes

129
Q

t/f

puppies are born w/in the amnion

A

true

130
Q

t/f

it is normal for bitch to lick her vulva a lot during birth

A

true

yes, she should be doing this - she is cleaning the allantoic fluid

131
Q

why does the bitch’s tail arch during parturition?

A

it arches when something is engaged in the birth canal

132
Q

t/f

it is normal bitch to chew the amnion with her incisor teeth and ingest it

A

true

she likely did not eat her last meal so needs calories

133
Q

t/f

it is best to be present to assist the bitch during her labor

A

false

leave her alone - you being there likely stresses her out

134
Q

queen signs of impending parturition?

A

body temperature falls to less than 99* F

mammary glands will swell

135
Q

2nd stage of labor in queen?

how much time btwn each kitten?

A

first kitten delivered in 30-60 mins

5 mins to 1 hour may occur btwn kittens

entire litter w/in 2-6 hours (up to 12 is okay)

136
Q

3rd stage?

what does the queen do?

A

she eats fetal membranes as they are expelled

137
Q

t/f

queens, like bitches, have utero verdin expelled

A

false

138
Q

t/f

induction of parturition in dogs and cats is simple and done frequently

A

false

NO induction of parturition in dogs and cats

elective c section is the option

139
Q

when is elective c section performed in dogs and cats?

A

1-2 days before term or at first sign of labor

140
Q

what is minimum age of pups for survival?

A

cannot be more than 2 days pre mature or they will not thrive and have high chance of death

141
Q

which horn is MC pregnancy in alpaca?

A

left

142
Q

MC time for alpaca to give birth?

A

daylight

mid morning

143
Q

c/s of impending birth in alpaca?

what does the hembra do in first stages of labor?

A

udder development

seek solitude
humming sounds
spends more time on the dung pile

lasts 2-6 hours and up to 24 if it is her first birth

144
Q

duration of 2nd stage of labor in hembra:

A

30 mins - 2 hours

145
Q

what membrane covers fetus in alpaca birth?

A

epidermal membrane

146
Q

volume of placental fluid in the hembra?

A

small

147
Q

duration of 3rd stage of labor in hembra?

A

fetal membranes normally passed by 1 hour

4-6 hrs is okay

148
Q

when can labor be induced in hembra?

A

over 360 days of gestation

149
Q

what drug to induce labor in alpaca?
mechanism
how soon will labor occur?

A

250 ug - MICRO grams - of cloprostenol

destroy CL!

labor w/in 24 hours

150
Q

t/f

cria need dex for maturation of lungs at induction of parturition

A

false

NOT needed