Gestation and Parturition Flashcards

1
Q

What is the average gestation length?

A

340 days

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2
Q

What is the range of gestation length?

A

320-365 days (or more)

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3
Q

At what point is the foal viable?

A

320 days

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4
Q

What factors affect gestation length?

A

-mare body condition (thin = longer)
-day length (Jan/Feb mares have longer gestation)
-health of mare/foal (health issues may cause early foaling)
-breed/type (ponies have shorter gestation)
-foal sex (gestation with colts is usually longer)

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5
Q

At Day 0 of gestation what occurs?

A

ovulation, fertilization occurs in the oviduct

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6
Q

At day 6ish of gestation what occurs?

A

conceptus leaves the oviduct
-it is mobile in the uterus

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7
Q

When is the conceptus detectable in the uterus (with a high powered ultrasound)?

A

around day 9

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8
Q

At day 16ish of gestation what occurs?

A

conceptus fixes in a uterine horn
-detectable by ultrasound

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9
Q

At day 23ish of gestation what occurs?

A

the heart beat is present
-detectable by ultrasound

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10
Q

At day 40 of gestation what occurs (as early as day 35)?

A

embryo transitions to fetus
-fetal activity and physical development (looks like a horse now)

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11
Q

At day 90ish of gestation what occurs?

A

placental development is complete

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12
Q

At day 240 of gestation to parturition what occurs?

A

most fetal mass is accumulated (in the last 3 months)

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13
Q

Early embryonic loss

A

loss of conceptus prior to 35-40 days (post ovulation)

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14
Q

Abortion

A

loss of pregnancy between 40 and 310 days (fetus is not viable between these times)

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15
Q

Premature delivery

A

weak or dead foal pre-term (usually less than 320 days)

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16
Q

Dystocia

A

a difficult delivery (a full-term dead foal is not considered an abortion)

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17
Q

What are the two sacs of the placenta?

A

-amnion
-chorioallantois (allantochorion)

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18
Q

Amnion

A

a white translucent sac of the placenta
-surrounds the fetus
-contains amniotic fluid

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19
Q

Chorioallantois (allantochorion)

A

a sac of the placenta that surrounds the amnion
-contains allantoic fluid (the “water”)
-has two sides: chorion and allantois

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20
Q

Chorion

A

the side of the chorioallantois that is attached to the uterus

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21
Q

Allantois

A

the side of the chorioallantois that is on the side towards the fetus

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22
Q

Umbilical cord

A

contains blood vessels that transport nutrients and oxygen to the fetus and takes CO2 and some other wastes away

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23
Q

What does the umbilical cord connected to?

A

the chorioallantois through several tissue layers (keeps the blood cells apart but lets the nutrients/O2 in and the CO2 out)

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24
Q

Do maternal and fetal blood supplies mix?

A

No

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25
Q

Urachus

A

connects to the fetal bladder and empties into the allantoic fluid

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26
Q

Where is the urachus found?

A

in the umbilical cord

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27
Q

Parturition overview:

A
  1. the foal breaks through the chorioallantois placenta, allantoic fluid (the water) spills out
  2. the amnion emerges
  3. the foal breaks the amnion then emerges
  4. the placenta is expelled
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28
Q

Pre-partum changes in mares

A

-loosening of tail muscles (relaxed pelvis)
-elongation of vulva
-udder development

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29
Q

Stage I of parturition lasts how long?

A

1-3 hours

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30
Q

What occurs during stage 1 of parturition?

A

-foal changes position
-uterine contractions become more apparent
-mare may be uncomfortable, paw, sweat, roll, etc.
-rupture of the chorioallantois at the end (“water breaking”)

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31
Q

How long does stage 2 of parturition last?

A

less than 40 minutes (less than 20 minutes is better)

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32
Q

What occurs during stage 2 of parturition?

A

-begins with the rupture of the chorioallantois (water breaking)
-ends with expulsion of the foal

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33
Q

Steps of stage 2 of parturition:

A

-chorioallantois ruptures
-amnion should appear first (white)
-one front foot, the other front foot, and then the head of the foal should appear
-rest of the foal comes out
-the umbilical cord should break when the mare or foal stands

34
Q

Normal foal position during parturition:

A

diving position
-front foot sole towards mares hocks
-second foot
-nose
-shoulders
-hips
-then hind limbs

35
Q

Why does one front foot go in front of the other?

A

to make the shoulders more narrow to fit through the birth canal

36
Q

How long should stage 3 of parturition last?

A

less than 3 hours (less than 1 hour is better)

37
Q

What occurs during stage 3 of parturition?

A

-ends with the expulsion of placenta
-no expulsion within 3 hours is a retained placenta and an emergency

38
Q

What should be checked for immediately post-partum with the foal?

A

-breathing
-righting reflex (sitting up)
-suckle reflex (within about 20 min)

39
Q

The 1, 2, 3, +3 Rule

A
  1. Foal is able to stand within ONE hour
  2. Foal nurses within TWO hours
  3. Meconium passed withing THREE hours
    +3. Placenta is passed within THREE hours
40
Q

Meconium

A

the first manure of the foal
-thick and sticky
-if foal is struggling to defecate, give an enema

41
Q

What should be done with the umbilical stump?

A

it should be disinfected 3-4 times/day for 1-3 days with dilute chlorhexidine (Nolvasan)

42
Q

Early post-partum foal respiration rate:

A

80 rpm

43
Q

Foal respiration rate:

A

30-40 rpm at rest

44
Q

Foal heart rate:

A

70-120 bpm
-depending on if they are resting or standing/nursing

45
Q

Foal temperature:

A

99.5 to 102 degrees F

46
Q

What should a foals birth weight be?

A

9-10% of expected mature weight

47
Q

What should the placenta weigh?

A

about 11% of the foal’s birth weight
-very small or very large could indicate a problem during gestation

48
Q

A foal is born with limited ______ _______

A

disease protection

49
Q

Why is a foal born with limited disease protection?

A

-no transfer of antibodies to pathogens across the placenta

50
Q

Where are antibodies in the mare concentrated?

A

in the colostrum (IgG antibodies)

51
Q

Passive transfer of immunity

A

what is provided when the foal nursing colostrum off the mare
-the foal is not making the antibodies themselves

52
Q

When is the best time for the foal to absorb the IgG from colostrum?

A

0-12 hours after birth

53
Q

What is going on with the foal’s gut from 0-12 hours after birth?

A

there is high gut “permeability”
-facilitates absorption of immunoglobulins in colostrum
-other large pathogens can be absorbed now too though (possibly pathogens)

54
Q

What happens about 12 hours after birth?

A

“gut closure” begins
-can be earlier in some cases
-harder for foals to absorb large compounds

55
Q

When does gut closure end?

A

it is usually complete by at least 24 hours
-too late for colostrum now

56
Q

Colostrum levels can vary if:

A

-the mare started dripping colostrum before parturition
-it transitions to milk rapidly

57
Q

What does a good quality colostrum look like?

A

gold/yellow, thick, and sticky

58
Q

You can increase antibodies to common pathogens in colostrum by:

A

-vaccinating (3 wks - 1 month before the expected foaling date)
-natural exposure to where the mare is foaling, especially if foaling at a different location than where the mare normally lives

59
Q

If colostrum quality is low what should you do?

A

give colostrum from the farm’s “bank” or purchase from a commercial colostrum bank (does not have antibodies from your farms environment though)

60
Q

What is the recommended intake of colostrum?

A

1-2 liters per foal (about 1/2 a gallon)

61
Q

How are IgG concentrations assessed?

A

in foals blood

62
Q

When should IgG levels be tested?

A

about 12-24 hours of age (earlier the better so you have time to fix it if its low)

63
Q

What is low IgG levels a risk of?

A

it is a risk factor for neonatal disease
-sick foals presented to the clinic have lower Ig levels than healthy foals presented to the clinic

64
Q

Optimal Ig concentration is:

A

8-12 g/L

65
Q

Hyperimmune Plasma

A

plasma given IV to supplement and increase antibody concentrations if colostrum wasn’t given before 24 hours

66
Q

Udder scoring system

A

0 = udder is not producing anything yet, it would appear soft and normal
1 = usually starts about 3 weeks from foaling. There is a small amount of milk production but the udder is still soft
2 = you can feel milk production but the udder is not tight
3 = the udder is tight and full and the teats are pointed outwards
W = wax, the mare is very close to foaling

67
Q

Foal-alert system

A

a device that gets sewn into one side of the horse’s vulva. It has a magnet that is sewn into the other side of the vulva and a string connects the two sides. When the string gets disconnected from the magnet, the system will set an alarm off. The alarm is set off when the foals front leg/legs hits the string and disconnects it during stage 2 of labor. It is usually inserted when the mare has an udder score of 3 or no later than her due date if the udder is not developing.

68
Q

Signs that a pregnant mare is affected by fescue toxicosis

A

-prolonged gestation
-little to no mammary gland development (even close to foaling)

69
Q

Why is examining the placenta after foaling important?

A

it can tell you of any complications during pregnancy and more about the issues a mare possibly had during pregnancy that could be a problem for her foal. Also if part of the placenta is retained, that is an emergency and the mare is at severe risk of infection and must get vet care

70
Q

Where does the chorioallantois usually rupture during foaling?

A

at the cervical star

71
Q

Hippomane (allantoic calculi)

A

an oval mass that is tan or brown in color and is passed along with the placenta
-it is an aggregate of cells, lipids, and debris that can accumulate during normal gestation

72
Q

Foaling kit

A

a kit prepared at the beginning of the season before the first foal is due
-gloves
-flashlight
-stethoscope
-scissors/suture scissors
-umbilical dip cups and colostrum sample cups
-bottle
-enemas
-bailing twine (to tie placenta)
-brown gauze (to wrap mares tail)
-towels

73
Q

When is the udder score determined?

A

in the morning
-in the afternoon udders can go down with movement/exercise throughout the day

74
Q

Refractometer

A

used to test colostrum quality
-0-30

75
Q

What number on the refractometer tells you it is poor quality and colostrum from the bank should be used?

A

anything less than 21

76
Q

Pregnant horn appearance?

A

thicker, fuller, larger

77
Q

Non-pregnant horn appearance

A

shriveled, smaller

78
Q

Chorion appearance

A

red, velcro-like, veiny

79
Q

Allantois appearance

A

soft, velvet-like (inside of placenta)

80
Q

Red bag

A

premature separation of the placenta
-the cervical star did not tear so you see the red chorionic surface first
-EMERGENCY, foal is not getting enough oxygen

81
Q

Characteristics of the placenta that is evaluated:

A

-color (no discoloration spots)
-both horns are intact
-look for tears
-weight