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ANS 327 MT 2 Questions
Yup
38
Agriculture
Undergraduate 4
11/17/2008

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Term
Define parturition
Definition
Parturition is the expulsion of both fetus and fetal membranes
Term
What is responsible for inducing parturition?
Definition
Fetal cortisol- released from pituitary
Term
Describe general Stage I parturition
Definition
Cervical dilation,initiation of myometrial contractions, chorioallontoic membranes rupture and release allantoic fluid
Term
Fetal endocrine events prior to parturition
Definition
stressors trigger fetal hypothalamus to release corticotropon releasing hormone (CRH) --> stimulates release of adrenocorticotropic hormone (ACTH) from posterior pituitatry --> stimulates release of cortisol from the adrenal gland
Term
Maternal endocrine events prior to parturition
Definition
Progesterone declines, estradiol increases, PGF2a increases and then plummets shortly after parturition
Term
Enzymes released once fetal cortisol is released
Definition
17a hydroxylase, C17-20 lyase, aromatase and they convert prostaglandin to estradiol
Term
physiologic importance of prostaglandin decline
Definition
removes prostaglandin block from myometrial contractions, allows for full contractility of myometrium
Term
physiologic importance of the increase in estradiol
Definition
Estradiol causes the secretion of cervical mucus, helping aid in parturition
Term
Physiologic importance of change in PGF2a
Definition
Causes regression of CL (helping lower prostaglandins being released from CL),works synergistically with estradiol to increase myometrial contractility
Term
General stage II parturition
Definition
powerful myometrial contractions as well as abdominal contractions, fetus into cervical canal triggers stretch receptors --> stimulates oxytocin release from pituitary --> stimulates release of prostaglandins helping increase power of myometrial contractions, delivery of fetus marks end of stage II
Term
General stage III parturition
Definition
Myometrial contractions still present but less powerful and less frequent, fetal membranes expelled
Term
indication of parturition onset (cattle)
Definition
udder is edematous and may leak colostrum, pelvic ligaments relax so gluteal muscles relax and tail head appears raised, vulva becomes edematous and vulvar cleft elongates
Term
stage I signs (cattle)
Definition
restlessness, arched back, extended tail, shifting weight, seeking isolation, straining of abdominal muscles at end of stage I
Term
length of stage I (cattle)
Definition
~6 hrs (shorter 3-4 hrs in mature cows, longer in first time heifers up to 24 hours)
Term
describe passive phase of cervical dilation
Definition
external os dilates while internal os remains closed
Term
describe active phase of cervical dilation
Definition
strong contractions maneuver fetus into cervical canal, causes stretch, induces release of oxytocin
Term
during start of stage II, is amnion in cattle still intact or ruptured?
Definition
Intact
Term
When/how does placental separation occur in cattle? What does this do to the fetus?
Definition
Gradually in the 2nd stage. Makes fetus hypoxic but not usually acutely anoxic
Term
how long is stage II in cattle?
Definition
up to 8 hours, 6 is ideal
Term
How long are myometrial contractions observable after parturition?
Definition
2-4 days
Term
What is dystocia?
Definition
Dystocia is difficulty with parturition because either the 1st or 2nd stage were unable to be completed
Term
what are the most common causes of dystocia?
Definition
fetopelvic disproportion, primary uterine inertia, secondary uterine inertia
Term
what is primary uterine inertia?
Definition
failure of the myometrium to contract enough to push the fetus into the cervical canal despite cervical dilation, parturition does not proceed past 1st stage
Term
what is secondary dystocia?
Definition
failure to expel the fetus, muscle exhaustion and/or cessation of responsiveness to contraction stimuli; parturition does not proceed past 2nd stage; commonly seen with fetopelvic disproportion
Term
why might one decide to terminate pregnancy in cattle?
Definition
accidental breeding of heifers, or unwanted pregnancy in feedlot heifers
Term
What are the sources of progesterone in cattle and at what stages are they responsible for releasing it during pregnancy?
Definition
CL for the first 150-200 days, placental membranes for second portion
Term
How much progesterone is required to be in the blood in order to maintain pregnancy?
Definition
~1ng/mL
Term
How can one cause abortion in cattle?
Definition
Prior to 150 days, 25 mg of PGF2a; after 150 days to cause abortion or induce parturition is to use dexamethasone (25 mg) and PGF2a (25 mg)
Term
How long after parturition is the point of retained placenta?
Definition
More than 12 hours post parturition
Term
What are the causes of retained placenta in cattle?
Definition
lack of proteolytic breakdown, which leaves the membranes intact; or insufficient myometrial contractions (commonly seen with dystocia)
Term
what are some of the major differences of parturition in horses as compared to cattle?
Definition
Horses have a much shorter stage 1, and especially stage 2; detachment of the fetus from the membranes is rapid and complete; dystocia is less prevalent in mares
Term
What is the difference in cervical dilation in horses as compared to cattle?
Definition
Horses cervices dilate in an active phase only
Term
which drug is used to induce parturition in mares?
Definition
Oxytocin
Term
What must be present in order for swine to have early recognition of pregnancy? Parturition?
Definition
at least 4 viable embryos; 2+ fetuses to release enough fetal cortisol
Term
which drugs are used to induce parturition in swine?
Definition
PGF2a and prostaglandin
Term
What is "ringwomb"?
Definition
Inability of cervix to dilate (sheep and goats)
Term
What does the ewe depend on for progesterone to maintain pregnancy?
Definition
CL up to day 60, after that placenta (ewe is therefor placental-dependent)
Term
what does the doe depend on for progesterone production to maintain pregnancy?
Definition
CL throughout pregnancy (therefor luteal dependent)
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