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Bovine Pregnancy, Placentation, Parturition

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sihirlifil's version from 2017-09-15 15:46

Bovine Pregnancy Diagnosis

Question Answer
The 4 definitive signs of pregnancyFetus (lol)
Amniotic vesicle (30-65 days)
ChorioAllantoic (fetal) membrane slip (35-90 days)
Placentomes (from 70d, easier 120d)
Rough estimate of bovine fetus size: mouse60d
Rough estimate of bovine fetus size: rat90d
Rough estimate of bovine fetus size: small cat120d
Rough estimate of bovine fetus size: large cat150d
Rough estimate of bovine fetus size: beagle dog180d
Non-definitive signs of pregnancy (3)Thinning of uterine wall
Increase in diameter of uterine horns
Presence of fluid (turgidity)
Uterine wall in non-pregnant uterus is ___mm. thick; intercaruncular areas of pregnant uterus are ___mm. thick9-10; 2 (thinner)
What does turgidity mean?Pressure of fluid within the uterus (feels like water balloon), about day 35-40
When is presence of fluid in a thin-walled uterine horn sufficient for pregnancy diagnosis?Between 30-50 days (fetal membranes and amniotic vesicle are fragile) for clinicians who have had experience diagnosing thousands of pregnancies at this stage
Rough handling of uterus and palpation of membranes and AV can cause pregnancy loss
When cows are palpated between 30-90 days what are the definitive signs of preg? After that?Amniotic vesicle & FMS. Then fetus is palpable & eventually cotyledons
Amniotic vesicle = Small balloon within the larger balloon of allantoic space
T/F During early pregnancy the pressure within the amnion is greater than the pressure within the allantoisTrue
How do you locate the amniotic vesicle?Gentle finger & thumb palpation along entire uterine horns until round, firm, intra-uterine structure is felt (usually in free portion of the horn)
Can you feel the amniotic vesicle beyond 65 days?Not really- elongation and fluid accumulation make the amniotic vesicle less definitive
What is the fetal membrane slip (FMS)? when can you feel it?Between 35-90 days, compression of uterus allows allantoic membrane to slip between fingers
How do you palpate the FMS?Pinch whole horn diameter at the ovarian end (to aviod crushing conceptus). Should feel connective tissue/blood vessel band from the floor of the uterus as it slips out of your fingers
Special consideration for FMS?Should not look for FMS unless can identify fluid in the uterus
If you pinch the uterus hard enough, can mistake the endometrium slipping for the FMS
When are placentomes more accessible than the fetus?5-7 months of gestation
When can you palpate placentomes?100d (but formation starts earlier, experienced can find them earlier)
Placentomes in the pregnant horn are generallyLarger
Early on, where are placentomes best felt?Midline and at the level of the horn near intercornual ligament
Where do you palpate for placentomes?Dorsal wall of the uterus
T/F Placentomes are all the same sizeFalse- size varies along the uterus and tend to be bigger in the horn with the fetus. If using size to estimate pregnancy stage, use average
How does the uterine artery indicate pregnancy?Increases in diameter, especially in pregnant side
Alteration in character of pulse
Characteristic pulse in the uterine artery is calledFremitus
Where do you detect fremitus?Point where artery leaves the pelvis and enters the abdomen
Where is the uterine artery?In the broad ligament as it passes forward from the iliac shaft to the pelvic brim, reaches mid-cornual region
What happens to the uterine artery as the uterus descends?Pulls artery away from the ilium
As the uterus descends, the uterine artery is more mobile than the ___ ___ artery. (How do you distinguish them?)Internal iliac
Int. iliac is adherent to iliac shaft- feel around it (can't get fingers around the iliac)
When does uterine artery enlargement become noticeable? when does fremitus start?Noticeable at 80-90d
Fremitus by 90-120d in pregnant horn
What problem may cause enlargement of the uterine artery?Pyometra
At 90d the uterine artery is ___mm.3
At 120d the uterine artery is ___mm.6
At 150d the uterine artery is ___mm.9
At 180d the uterine artery is ___mm.12
When is it difficult to palpate the fetus? Why?5-6 months, due to depth of abdomen
Fetal movement may be elicited by when?After 6 months
Before 60-70d, what hinders palpation of the fetus?AV
How useful is palpation of the ovary?Not distinguishable from non-pregnancy, but CL must be present, usually ipsilateral to pregnant horn. CL remodels itself over the course of pregnancy but isn't diagnostic
What happens to the uterus, cervix, and ovaries as pregnancy progresses?Move forward and downward in the abdomen
Cervix appears fixed at the pelvic brim (but in some multiparous cows this can be its normal position, and weight of non-pregnant fluid can fix the same way)
Estimation of preg stage: 30-40d?Presence of AV 0.7cm diameter
FMS in some cows
Asymmetry of horns
Estimation of preg state: 42d?Pregnancy is readily detectable in almost all animals
Fluid in uterus, skinny balloon, thinning uterine wall, diameter of horn increases to 4-5cm
AV 1.5cm
Fetal membranes
Size of AV at 48d? 52? 58? 65?48: 3.8cm (2 fingers)
52: 5.5cm (3 fingers)
58: 7.5cm (4 fingers)
65: 10.5cm (hand+thumb)
(Fetal crown-nose length at 70d? 80?)(1.5cm --> 3.8cm)
(Same size as AV was at 42 & 48 days)
Estimation of preg stage: 84d (12 weeks?)AV has disappeared (lost distinctive fluid pressure) by 65-70d
Uterine diameter continues to increase
Caruncles can first be felt as thickenings of the uterine wall 1-2cm in diameter
(Fetal crown-nose length at 90d? 100?)(5.5cm ---> 7.5cm)
Estimation of preg stage: 112d (16 weeks)?Marked increase in full-water-balloon feeling of uterus
Uterine diameter increased
Caruncles increased in size (nickel-sized)
Uterine artery increased to 0.5cm wide and fremitus readily apparent (started at 90d)
(Fetal crown-nose length ~9cm)
Estimation of preg stage: 140d (5 months)?Uterus completely flaccid (gradually lost fluid over a month), i.e. no convex surface
Placentomes average 4-5cm in diameter
Fremitus starts in non-pregnant side
Estimation of preg stage: 150d?Uterus in abdomen
Quarter-sized placentomes
Estimation of preg stage: 180d?Half-dollar-sized placentomes
Estimation of preg stage: 196d (7 months)?Weight of fetus and fluids have dropped the uterus to the abdominal floor (difficult to reach)
Uterine artery 1.5cm diameter
Placentomes size increase (more than half-dollar)
Fremitus becomes weaker (i.e. pulse progressively less clear)
Difficult to grasp fetus
Estimation of preg stage: 210-225d?Ascent of uterus commences
Estimation of preg stage: 240d (8 months)?Fetus rises up in abdomen, readily palpable and possible to recognize fetal limbs & head
(Chart of rectal findings to diagnose pregnancy)(draw some arrows)
memorize

Placentation

Question Answer
3 of the 4 definitive signs of pregnancy for diagnosis by palpation per rectum are?Aspects of the fetal membranes
The 3 major types of placenta in domestic animals based on gross anatomy:Diffuse
Cotyledonary
Zonary
Ruminants have ___ placentationCotyledonary
Cats and dogs have ___ placentationZonary
Horses and pigs have ___ placentationDiffuse
Chorion =Outermost membrane, attached to the endometrium ‘one way or another’ (and to the allantois)
Amnion =Membrane that surrounds the fetus
Allantois =Balloon within the chorion that lines the chorion and amnion
How are the chorion and amnion arranged?Layered against each other so there’s 1 physical membrane (chorio-allantois)
How are the amnion and allantois arranged?Layered against each other so there’s 1 physical membrane (amnio-allantois)
Fluid in the outer balloon is calledAllantoic fluid
Fluid in the inner balloon is calledAmniotic fluid (surrounds the fetus)
The ___ is intimately attached to the endometriumChorion
Why are the endometrium and chorion attached?Transfer of essential nutrients
What does the chorion look like?Rough, red/discolored
What is ‘Red Bag?’Detached chorion observed at foaling (‘convenient layman’s term’ lol)
(Be able to draw the fetal membranes as they appear at term in the horse)(why tho)
What are fetal cotyledons?Growths that develop at specific sites in the uterus
T/F Cotyledons develop at random in the uterusFalse- Each uterine horn has line of pre-developed caruncles to which the fetal chorio-allantois attaches to form the placentome
Placentome a.k.a.Fetal/maternal defined connection point in the uterine horn
How are caruncles in each uterine horn arranged?4 lines of 15 in each
Most of these potential sites are used during pregnancy
T/F The fetal membranes use caruncles in both hornsTrue! The fetus is associated with 1 horn but membranes use both
Size of the placentomes is ___ closer to the fetusLarger
What is IFN-tau?Signal sent to the uterus for prevention of PGF2a-induced luteolysis
IFN-tau comes fromPlacenta
Besides IFN-tau, how else does the fetus make its presence knownElongates to fill the horns
Major placental disease issue in the cowRetained placenta
T/F Retained placenta is an emergency conditionTrick question >:)
Not emergency in cow
Emergency in horse
Anomalies in placental development have been associated with what?Certain genetic aspects of breeding cattle
Assisted reproduction (IVF/cloning)
Adventitious placentation =Fetal cotyledons form beyond the boundaries provided by the maternal caruncles
Adventitious placentation is associated withAbnormal conditions e.g. hydrallantois
memorize

Pregnancy and Termination of Pregnancy in the Cow

Question Answer
Indications for elective termination of pregnancyMismating (wrong bull, heifer too young, heifer going to feedlot)
Pathological pregnancy (hydroallantois, hydramnios, fetal mummification/maceration)
How and when does the CL maintain pregnancy?Produces P4 for 150 days, then during the last month of gestation (does not regress when placenta takes over at 150d)
Ovariectomy before 5 months gestation causesAbortion
Ovariectomy after 200 days (~7 months) causesNO ABORTION- pregnancy continues. Decrease in P4 levels, shortening of gestation by 2 weeks
Problems with ovariectomy after 200 days?Dystocia and retained placenta (gestation shortened by 2 weeks)
What are P4 levels throughout gestation?Fluctuating 6-15ng/mL
During the last month, P4 isDeclining gradually
From day 0-150, ___ provides P4CL
From day 150-250, ___ provides much of P4Placenta
From day 250-term (270-295d), ___ provides much of P4CL again
How do we induce abortion with P4?Reduce it to less than 1ng/mL
What do we have to keep in mind when inducing abortion?Have to target correct source of P4 for the stage of gestation
Use combined treatments
What physical methods can be used to terminate pregnancy?Rupture of AV
Decapitation of fetus between 65-90d
IU infusions
Enucleation of CL
Most common methods of terminating pregnancyPGF2a (& analogs)
Glucocorticoids
When is the CL sensitive to PGF2a5-7 days post ovulation
Up until when can PGF2a cause abortion?150 days
What happens when you give PGF2a in the last month of pregnancy?Induces parturition
What happens when you give glucocorticoids in the last month of pregnancy?Induces parturition
What happens when you give glucocorticoids during days 150-250?Induces abortion when used in combination with PGF2a
T/F Estrogen is commonly used to terminate pregnancyFalse. Questionable efficacy, considered obsolete
Effects of estrogen? When?Luteolysis and abortion up to 150 days
May speed induction of parturition with glucocorticoids
T/F Oxytocin interferes with the formation of the corpus luteumTrue
When is oxytocin given to terminate pregnancy?2-7 days after estrus (so give it early!)
Indications for induction of parturition (4)Seasonal calving (specific to New Zealand)
Management/manpower/facilities considerations
Health of cow
Reduce calf size
Categories of methods for inducing parturition (3)Long-acting corticosteroids
Short-acting corticosteroids
Prostaglandins
Calves born more than ___ prematurely have reduced viability2 weeks
Why is an accurate breeding date required for induction of parturitionCalves born more than 2 weeks premature have reduced viability
Long-acting corticosteroids: are what? inject when? parturition happens when?Insoluble esters or suspensions
1 month prior to due date, parturition in 4-26 days
Advantages of long-acting corticosteroids? Disadvantages?Lower incidence of retained placenta than other methods, but high calf mortality
(Examples of long-acting corticosteroids)(Dexamethasone trimethylacetate
Triamcinolone acetonide
Flumethasone suspension
Betamethasone suspension)
Short-acting corticosteroids: are what? injected when? parturition happens when?Soluble esters
Injected 2 weeks before due date, parturition in 1-3 days
Advantages of short-acting corticosteroids? Disadvantages?No increased risk of calf mortality, but high % retained placenta
(Examples of short-acting corticosteroids)(Dexamethasone
Flumethasone
Betamethazone)
T/F Prostaglandins have similar results to using long-acting corticosteroidsFALSE- short-acting
(Examples of prostaglandins)(PGF2a
Cloprostenol
Fenprostalene)
Gestations length of cowMost breeds of domestic cattle have a mean gestation length between 275 & 295 days (Jersey = 279; Holstein = 283; Angus = 281; Brahman = 292)
memorize

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