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
2
Q
cow gestation length?
variation?
A
280
+/- 14 d
longer in Bos indicus
3
Q
mare gestation length?
variation?
A
340 days
320–360
4
Q
sow gestation length?
A
114 d
5
Q
doe and ewe gestation length?
A
150 days average for both
dow: 148-1555
ewe: 145-150
6
Q
bitch gestation length and timing?
A
65 d from LH surge
+/- 1
also: 57 +/- 2 from cytological diestrus 1
7
Q
queen gestation length and timing?
A
63 days from ovulation
8
Q
hembra gestation length and timing?
variation?
A
334 d from breeding
320-360 variation
9
Q
pregnancy is complex interplay btwn what entities?
A
dam, endometrium, myometrium
ovaries with CLs on them
placenta
fetus, fetal membranes
10
Q
what hormone controls endometrial secretions in the bitch?
A
p4
11
Q
what hormone maintains preg?
A
p4
12
Q
how does p4 maintain pregnancy?
what mechanisms in the bitch?
A
endometrial gland secretions
uterine circulation
myometrial quiescence
cervical closure
13
Q
what is a source of p4 in all species?
A
CL
14
Q
the placenta is an additional source of p4 in what species?
A
mare
ewe
queen
15
Q
what additional source of p4 is suspected in cattle?
A
adrenal gland
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
17
Q
what is basic structure of myometrium?
A
smooth muscle structure
actin and myosin muscle fibers - slide across each other to contract
18
Q
what enzyme is required for myometrial contraction?
what is it activated by?
A
MLC kinase
activated by calmodulin
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
20
Q
what contributes to the Ca levels in the myometrial cells?
A
sarcoplasmic reticulum
extra cellular fluid compartment
21
Q
what governs the influx of Ca into myometrial cells?
A
CAPS
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
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
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
25
how is the myometrium prevented from contracting during pregnancy?
the contraction cascade is suppressed
26
what is the "rate limiting step" in a normal pregnancy, to begin the parturition cascade?
fetal hypoxia
b/c the fetus needs outgrow the supply capacity of the placenta
27
fetal hypoxemia triggers what hormonal cascade in the fetus, which leads to parturition?
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
28
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?
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
29
t/f
neither PG nor cortisol leave the feto-placental compartment to enter the maternal circulation at the time of parturition
true
both remain in the feto-placental compartmenet
30
what is the action of PG in the placenta?
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
31
what is the role of fetal cortisol in the hormonal cascade at initiation of parturition?
induce enzymes that convert androgens into estrogens
32
after e2 prod inc, as a result of the fetal hormonal cascade, where does it go and what does it do?
e2 crosses the placenta into maternal circulation
induces the formation of CAPS in myometrial cells -> to prepare them for contraction ability
33
for species with the placental source of p4, what hormonal changes occur at initiation of parturition?
pathway changes from p4 production to e2 production
34
for animals that rely on the CL for p4 at the end of the pregnancy, what triggers luteolysis to end the pregnancy?
sec of oxytocin => stim sec of PG => luteolysis
35
where is oxy that lyses the CL at the end of pregnancy sec from?
from the placenta or the CL itself
36
where is PG sec from, after stimulation by oxy?
the endometrium
37
what hormone causes ripening or softening of the cervix?
relaxin
38
what is the mechanism of relaxin?
dissociation of collagen disuphide bonds => dissociation of fibers => cervix opens
39
what is the origin of relaxin?
placenta or CL
40
in addition to relaxin, what other molecules contribute to softening of the cervix?
metalloproteinases
41
what molecule is selectively up regulated in the cervical muscle cells to promote cervical softening?
cAMP
42
what cell influxes into the cervix?
what cytokine stimulates this movement?
result?
NTs influx into cervix under the stimulation of Interleukin 8
degranulate -> sec inflammatory mediators -> dec uptake of Ca into myometrial cells -> promotes relaxation
43
what happens to conc of Ca in myometrial cells during softening of cervix?
dec
44
what effect does e2 have on cervix?
softening -> opening
45
what stimulates the transition of the allanto-chorion into the cervix?
the inc pressure in the myometrium d/t contraction
46
what mechanical force helps push the cervix open as it ripens?
the allanto-chorion pushing on the cervix forces it to open
47
what stimulates stage 2 of labor?
the onset of abdominal pressure
subsequent the neuro endocrine reflex - Ferguson's reflex
48
what is Ferguson's reflex?
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
49
in response to pelvic filling, what voluntary action must occur?
mare must abdominal press
50
t/f
you can see uterine contractions from outside the body
false
you see abdominal contractions, NOT uterine contractions
51
what is stage 3?
expulsion of fetal membranes
52
what species expels a whole placenta rather than fetal membranes?
bitch
53
what is involved in separation of fetal membranes from the endometrium?
```
proteolytic enzymes
leukocyte enzymes
oxytocin
PGs
mechanical pull
```
54
what does the presentation of the fetus describe?
longitudinal axes of dam and fetus
55
how can a fetus appear if in a longitudinal presentation?
cranial or caudal longitudinal - axis of fetus parallel to axis of dam
head or butt facing out
56
what is a transverse presentation?
ventral if legs/belly first
dorsal if spine first
57
what does the position of fetus describe?
examples?
the portion of the maternal pelvis against which fetal spine lies
dorso-sacral
dorso-pelvic
dorso-ileal (Left or Right)
58
MC position of fetus at time of parturition?
dorso-sacral -> spine directed against sacrum of dam
59
what does posture of fetus describe?
what is MC / proper posture?
the angulation / flexion of head, neck and presenting limbs
head and forelimbs should be extended in most animals with both front limbs extended
60
what are sings of pre partum cow indicating she will calve soon?
what hormones is she under the influence of?
```
last week: vulva swells and lengthens
48-24 hours: cervical musus
24 h: tone of tail is poor
udder development
pelvic ligg relaxation
```
e2
61
when does the udder develop in the heifer?
cow?
heifer - as early as 4 mos in heifers
cow - 2-4 weeks before parturition
62
what is the appearance of colostrum pre partum?
thick, yellow, turbid
63
first stage of parturition - signs in a cow?
how long?
dec appetite
restlessness and separation
lasts 6-12 hours or up to 24 in heifers
64
MC time of day for calf delivery?
night
65
how does rumen fill affect calving?
rumen fill may delay calving b/c it delays the onset of active parturition
66
what happens during 2nd stage parturition in cows?
water breaks - rupture allanto chorion
67
what is the presentation and position and posture of the fetus at 2nd stage labor?
longitudinal, cr and dorsosacral
head and neck extended
muzzle at fetlocks
68
what is the widest diameter of the pelvis?
and of the calf?
diagonal across the pelvis
at the trochanters on the calf
69
how much force required to deliver a calf?
what % from abdominal press vs myometrial contractions?
70 kg
40% from myometrial contractions
60% from abdominal press
70
how long after parturition are fetal membranes expelled in the cow?
w/in 8 hours
71
what must occur for normal passage of fetal membranes?
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
indications to induce parturition?
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
minimum gestation of cow to induce parturition?
265 days
74
what drugs used to induce parturition in cow?
dexamethasone
PgF2a
75
fxn of dex in parturition induction in cow?
crosses placenta into fetal compartment -> induces endocrine cascade for labor
also: induces fetal lung maturation via inc surfactant production for c section
76
even for a c section, it is necessary to induce parturition in the cow medically.
why?
to ensure the calf if mature
77
what is the schedule of injections for a planned c section in the cow?
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
when parturition is induced in the cow, what % likely to have retained fetal membranes?
significance?
80%
usually resolves and no consequences
79
how does induction of parturition affect colostrum and passive transfer capability of dam in the cow?
it does not - this occurs normally
80
in the equine, what is the mechanism of action of fescue intoxication and interference with parturition?
px the rise in progestagens
81
late in gestation, what maintains pregnancy in the mare?
source?
5a pregnanes
the precursor is sec from fetal adrenal and converted by the placenta in the 5a pregnanes
82
what is the change in hormone profile at time of parturition in the mare that induces mammary development?
inc in p4
| dec in e2
83
what action of fescue intoxication leads to agalactia?
suppress prolactin sec
84
what is waxing in the mare?
colostrum production -> see milk accumulate at tips of teats
85
when does the mare begin milk prod?
when oxy levels inc and myometrial contractions begin
86
what does waxing in the mare indicate?
parturition is eminent
87
what is a very specific parameter that is easy to measure and means that the mare will go into labor very soon?
high Ca conc in milk
abrupt change
she will foal w/in 2 days
88
what are physical signs of parturition nearing you can see externally on the mare?
vulva becomes very looooong
| pelvic ligaments become lax
89
what is the appearance of the teats in the mare when she is near foaling?
flat teat cistern will become cylindrical
90
what is best method / sampling protocol for tracking Ca conc in mare milk to predict foaling?
what levels of Ca indicate foaling?
- 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
when Ca levels are below ____ ppm, foaling is RARE
200
92
MC time of day for mare foaling?
night
93
signs mare will foal that night?
inconspicuous
sweating, restless
running milk
colic
94
t/f
mares can "hold off" labor, and will do so if they are nervous or are being watched
true
give them space and quiet and to NOT bother them
95
what stage of labor in the mare does the foal assume his appropriate birthing presentation/position/posture?
during the first stage of labor
96
2nd stage of labor in foals?
how long until birth?
water breaks
very forceful, abdominal contractions
birth in 30 mins
97
typical position of mare during foaling?
lateral recumbence
98
in order to Px the foal from suffering and proceed with a normal birth, what membranes must rupture?
allanto chorion
if this does not rupture - if the water does not break - then that indicates the foal is suffocating
99
if the allanto chorion does not rupture appropriately, what should you do?
tear it open
100
t/f
the foal passes thru the birth canal w/in the allanto chorion
false
foal is in the amnion
the allanto chorion ruptures first
101
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
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
t/f
you should tear the umbilical cord immediately after birth
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
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?
less than 60 minutes
emergency after 4 hours
104
once expelled, which surface of the membranes are facing you?
the allantoic side is facing you and the chorion is the inner surface
the membranes get turned inside out with tension during parturition
105
what is minimum gestation length of mare?
320 days
106
t/f
it is relatively simple to determine fetal maturity in mare
false
why induction of parturition should be considered carefully and NOT rushed into and avoided if possible
107
what specific gravity should colostrum have to indicate it is mature?
1050 or higher
108
indications for parturition induction in the mare?
deformed pelvis, fracture, colic, etc
premature colostrum leakage
Hx of NI
109
how to induce fetal maturation in pregnant mare?
how long does it take?
dex
3 days
110
parturition induction drugs in mare?
how soon do they take effect?
mare
oxy => 10-20 units
should see 1st stage of labor w/in 20 mins
foal should be delivered w/in 60 mins
111
most reliable indication of parturition in small ruminants?
mammary gland development
behavior: separation from rest of the flock
112
what are timing of each of the 3 stages of labor in small ruminants?
1: separation from flock, 6-12 hours
2: Cr or Cd - 30-60 mins per lamb
3: 30-120 mins
113
indications for induction of parturition in small ruminants?
preg tox
vaginal prolapse
caprine arthritis encephalitis virus - observe birth to Px suckling and dec transmission
114
drugs to induce parturition in ewe?
16 mg dex
birth in 48 hrs
115
drug to induce parturition in doe?
16 mg dex
10 mg PgF2a
kid in 30-35 hours
116
why is dex important for induction of parturition in small ruminants?
induces fetal maturation of lungs
117
sow signs of parturition nearing?
7-10 days: mammary enlargement
3-4 days: vulva swollen
24 hrs: milk expressed from mammary gland
anorexia, restless, build nest (environment dependent)
118
length of each stage of labor in sow?
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
how much time is appropriate in btwn delivery of successive piglets?
15 mins avg
120
what is earliest a sow can be induced to farrow?
72 hours prior to due date
121
what drugs to induce parturition in sow?
when given relative to each other?
PgF: 10 mg
oxy: 5-30 units
give oxy 20-24 hrs AFTER PgF administration
122
t/f
dex is not necessary for piglet maturation
true
123
what are reliable signs of impending whelping in the bitch?
core temp drop by 2*, means birth in 12 hours
124
what hormone can be measured to indicate birth w/in 24 hours is likely in bitch?
p4
should be less than 2 ng/mL
125
first stage of parturition in bitch?
sign and timing?
nesting behavior
6-24 hours before birth
126
2nd stage labor in bitch?
0.5-3 hours
green/black vulvar discharge
127
what is the green / black vulvar discharge that occurs in 2nd stage parturition of bitch?
marginal hematomas
it is utero-verdin that is secreted
128
3rd stage of labor in bitch?
green / black parturient discharge
birth of pups and expel fetal membranes
129
t/f
puppies are born w/in the amnion
true
130
t/f
it is normal for bitch to lick her vulva a lot during birth
true
yes, she should be doing this - she is cleaning the allantoic fluid
131
why does the bitch's tail arch during parturition?
it arches when something is engaged in the birth canal
132
t/f
it is normal bitch to chew the amnion with her incisor teeth and ingest it
true
she likely did not eat her last meal so needs calories
133
t/f
it is best to be present to assist the bitch during her labor
false
leave her alone - you being there likely stresses her out
134
queen signs of impending parturition?
body temperature falls to less than 99* F
mammary glands will swell
135
2nd stage of labor in queen?
how much time btwn each kitten?
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
3rd stage?
what does the queen do?
she eats fetal membranes as they are expelled
137
t/f
queens, like bitches, have utero verdin expelled
false
138
t/f
induction of parturition in dogs and cats is simple and done frequently
false
NO induction of parturition in dogs and cats
elective c section is the option
139
when is elective c section performed in dogs and cats?
1-2 days before term or at first sign of labor
140
what is minimum age of pups for survival?
cannot be more than 2 days pre mature or they will not thrive and have high chance of death
141
which horn is MC pregnancy in alpaca?
left
142
MC time for alpaca to give birth?
daylight
mid morning
143
c/s of impending birth in alpaca?
what does the hembra do in first stages of labor?
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
duration of 2nd stage of labor in hembra:
30 mins - 2 hours
145
what membrane covers fetus in alpaca birth?
epidermal membrane
146
volume of placental fluid in the hembra?
small
147
duration of 3rd stage of labor in hembra?
fetal membranes normally passed by 1 hour
4-6 hrs is okay
148
when can labor be induced in hembra?
over 360 days of gestation
149
what drug to induce labor in alpaca?
mechanism
how soon will labor occur?
250 ug - MICRO grams - of cloprostenol
destroy CL!
labor w/in 24 hours
150
t/f
cria need dex for maturation of lungs at induction of parturition
false
NOT needed
