Obstetrical Management of Bovine Dystocia Flashcards
describe initiation of parturition
- fetal stress and ACTH releases fetal cortisol
- fetal cortisol and placental P4 are converted by enzymes to E2, which induces myometrial contraction, increasing pressure and cervical stimulation, resulting in oxytocin release and maximum pressure
-E2 also increases secretions by tract for lubrication - fetal cortisol causes release of PGF2a, which causes luteolysis and release of relaxin which allows for pelvic ligament stretching
describe the stages of parturition in the cown
stage 1: cervical dilation
-6-12 hours
-cervix dilates from 1-2 fingers wide 1 week pre partum to >12cm at parturition
-decrease in P4, increase in E2 and increase in PGF2a
-fetal head and limbs activate pressure sensitive neurons
-rupture of chorioallantois!! (end of stage 1)
-dystocia might occur because of prolonged or incomplete dilation
stage 2:
-2-4 hr in cows, 1-2hr in sheep and goats
-abdominal straining
-myometrial contractions (mediated by E2,, PGF, oxytocin)
-conical shape of head
-intact amnion appears at vulva
-amnion ruptures and then contractions are more forceful
-INTERVENE IF: 1 hour without significant progress
stage 3:
-placental expulsion
-1-24 hours in cows, 12-18hr in sheep and goats
describe parturition in sheep and goats
only 3-5% require assistance!
-but if delivery is not accomplished <3hr, cervix starts closing
describe normal presentation of ruminant babies
cranial or caudal longitudinal both normal
-transverse dorsal or ventral BAD
dorso-sacral normal
-dorsal-pubic or dorsal-ilial (right or left) abnormal; need to try to reposition!
head neck and limbs extended is normal
-retained or flexed abnormal!
describe dystocia in cows
- abnormal parturition; failure or prolonged 1st or 2nd stage
- maternal causes:
-uterine inertia: lack of expulsive force
-abnormalities of birth canal: inadequate size, pelvic deform, incomplete cervical dilation, neoplasia, uterine torsion
-BE CAREFUL with use of ecbolics! if cervix is closed and use oxytocin = uterine rupture, cervix must be open to use ecbolics! - fetal causes:
-fetal-maternal disproportion
-abnormal presentation, position, posture
-malformations
-twins
when see; BIOSECURITY
describe uterine inertia
primary: failure of myometrium to contract normally (hormonal defect, hypocalcemia)
secondary: exhaustion of myometrium after prolonged effort
describe dystocia in sheep and goats
- expect multiples normally = race to finish can cause tangles of fetuses
- preg tox
- tetanus prophylaxis
- if c section: beware of lidocaine toxicity in goats!
-conservative dose is 6mg/kg - normal delivery becomes dystocia when
-does in active labor for longer then 30 min with no progress
-abrupt cessation of parturition
-delivery of placenta without kid/lamb - most common cause is abnormal posture!!
-others: incomplete cervical dilation (ringwomb), simultaneous presentation of kids/lambs, cervicovaginal prolapse, uterine torsion, uterine inertia, feto-maternal disproportion (singleton, overweight ewe or doe)
describe management of dystocia
- history: previous dystocia, gestation length, progress, bull info, etc.
- retrain: clean, light, safe, +/- epidural
- physical exam: general conditions, discharges, abnormalities
- vaginal exam: check fetus and birth canal for presentation, position, posture
- rectal exam: only in a few cases
describe vaginal exam for dystocia
- clean and lubrication
- examine fetus and vagina for lesions and hemorrhage
- determine PPP
- determine if fetus alive or dead
- compare fetal-maternal size!!!!
- assess dilation of cervix, vagina, vulva
- select obstetrical options
- caudal epidural anesthesia
only 3-9% of ruminants can be born with caudal presentation
goats: dystocias higher on caudal presentation; 80% have flexed hind legs
describe ringwomb
- failure of cervix to dilate completely
-relatively common (23% incidence) - active labor with no kids delivered
- manual dilation is unrewarding
-may tear cervix or uterus - predisposing factors:
-hypocalcemia
-hormonal imbalance
-mineral imbalance
-prolonged dystocia
-twinning
what are the 5 obstetrical options
- mutations
- forced extraction
- fetotomy
- epysiotomy/symphysiotomy
- C- section
describe mutation
- repulsion: first step; push out pelvis to gain space
-if more than one fetus trying to exit at same time
-determine which legs belong wot which fetus
-ID 1st kid, repel 2nd kid, deliver 1st kid - extension: to correct flexion or retention of head or limbs
-head retained most commonly to fetal left side or down; use head snare (NEVER IN MANDIBLE; will not be able to nurse if deliver alive)
-push fetus back to gain room to pull head around
-forelimb flexion: correct carpal or shoulder flexion
-hindlimb flexion: only a problem if caudal presentation - rotation: turning longitudinal axis
-ex. dorso-pubic to dorso-sacral
-use detorsion rod: fix at chest, chains around shoulders, use bar to rotate - version: for transverse presentation
-traction and repel opposite poles
describe front leg malposture
- one or both front limbs retained
- some does may kid normally with one leg retained
- if both, only head may be protruding from vulva: swollen tongue
describe breech presentation
- requires straightening of both rear limbs
- push fetus cranially and to one side
- pulling and rotating the hock; foot is pulled ventrally and medially
- careful with fetal hooves!
describe delivery by forced extraction
- after correction of presentation, posture, position
- cleaning and lubrication
- use 2 people to avoid fractures, tears, paralysis
- force applied simultaneously to abdominal press
- NEVER head traction
- proper chain placement: first loop around fetlock and second loop around the pastern
-just one loop will cause a fracture! - pull through an arc = more natural
-avoid excessive forces - rotate fetus during traction once head and forelimbs pass the pelvis
- if caudal presentation, rush!! pelvic brim will press umbilicus and risk of fetal death and hypoxia
-if calf not delivered in 10 min: c section or fetotomy
