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