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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