Obstetrics Flashcards
What is the first step to successful delivery assistance? What should producers/owners do?
recognizing a normal delivery
triage pregnant animals
What triggers the beginning of parturition?
uterine crowding causes increased fetal ACTH, which initiates a cascade of hormonal changes
- fetus decides the date, dam decides the time
- larger litter = more crowding = shorter gestation
- singleton/mummy = no crowding = will not initiate parturition
What are the 3 stages of parturition?
- preparatory - uterine contraction, rotted fetal position (equine), chorioallantois/chorioamnios rupture
- fetus enters the vagina and is expulsed
- expulsion of fetal membrane
What is Ferguson’s reflex?
neuroendocrine reflex caused by the straining forces of the fetus against the cervix and cranial vaginal, inducing the release of additional oxytocin
What tends to increase the risk of a foal failing to survive during parturition?
every 10-minute increase in duration of labor at stage 2 beyond 30 mins
Parturition, differences in species:
In what 2 situations should intervention during parturition in mares be done?
- premature placental separation (red bag)
- foal not born within 20 mins after a mare releases allantoic fluid
In what 3 situations should intervention during parturition in cows be done?
- non-progressing parturition stage 1 (uterine torsion)
- > 2 hr after the first appearance of the amnion at the vulva
- no progress observed within a 30 min interval
In what 3 situations should intervention during parturition in bitches/queens be done? In bitches especially?
- no delivery of pup/kitten within 4 hours after the beginning of stage 2
- exhibit strong contraction for >30 mins without producing pup/kitten
- prolonged intercal (>2 hr) between delivery of pup/kitten
green vaginal discharge without delivering the first pup - obstructive dystocia, C-section recommended
In what 2 situations should intervention during parturition in small ruminants be done?
- fetal membranes at vulva for >3 hr without delivery - digital examination shows an incompletely dilated cervix (ringworm) –> C-section, dilation not helpful
- 30 min rule - examine 30 mins after the breaking of the chorioallantoic membrane and after delivery to look for an additional fetus
In what situation should intervention during parturition in camelids be done?
cria not born within 20 mins after the beginning of stage 2
- like mare, has a short stage 2
In what situations should intervention during parturition in sows be done?
piglet interval >2 hrs
What is the difference between superfecundation and superfetation?
successive fertilization of two or more ova by different sires –> more common in feral situations and in swine
successive fertilization of 2 or more ova of different ovulations, resulting in presence of embryos of unlike ages
What is the difference between ecbolic and tocolytic agents?
increase uterine contractions (PGF2a, oxytocin)
inhibit uterine contractions
- N-Butylscopolammonium (Buscopan) - anticholinergic
- Clenbuterol - anticholinergic
- epidural anesthesia
How is fetal disposition described?
- Presentation
- Position
- Posture
What is fetal presentation? What are the 3 terms used to describe it?
orientation of the fetal spinal axis to that of the dam and the portion of the fetus that enters the vaginal canal first
- LONGITUDINAL - anterior vs posterior, fetal spine parallel to dam’s
- TRANSVERSE - ventral vs dorsal, fetal spine not in like with dam’s
- VERTICAL - ventral vs dorsal, fetal spine is perpendicular to dam’s (dogsitting)
How is fetal position described?
LONGITUDINAL - based on the surface of the maternal birth canal to which the fetal vertebral column is applied OR the relationship of the fetal dorsum to the quadrant of the dam –> dorsal (dorso-sacral), ventral (dorso-pubic), left/right lateral (left/right dorso-ilial)
TRANSVERSE - relationship of the fetal head to the quadrants of the dam –> right/left cephalo-ilial
What is fetal posture?
disposition of the movable appendages of the fetus, involving flexion or extension of the neck or limb joints
- lateral flexion of the neck
- hock flexion
Fetal presentation, position, and posture:
What are 4 possible methods of obstetric manipulation to aid parturition?
- REPULSION - fetus repelled from the pelvic canal to increase space in the uterus to correct malposition
- MUTATION - manipulation of extremities with correction of postural abnormalities
- ROTATION - turning fetus on its longitudinal axis (hip-lock during calving)
- VERSION - manual changing of the polarity of the fetus with reference to the mother to correct transverse presentation –> head and forelimbs are repelled into the uterus while the hindquarters are pulled into the pelvic canal
What are 7 causes of dystocia?
- fetal materal disproportion
- faulty fetal disposition
- hereditary - schistosomus reflexus, hydrocephalus, anasarca
- nutritional - obesity (pelvic canal obstructed by fat
- infectious - dead fetus
- traumatic - hernia, rupture of prepubic tendon, tear of abdominal muscles
- uterine inertia
Causes of dystocia:
How are small animal dystocias most commonly resolved? What other method are commonly used in large animals?
medical
- mutation and rotation
- forced extraction
- fetotomy
- C-section
What restraints are recommended for assisted vaginal delivery and controlled vaginal delivery?
minimal - light sedation, epidural anesthesia, NEVER deal with it in a chute
general anesthesia
Before the decision of how to resolve dystocia, what should be done?
- check for fetal viability and distress - U/S for fetal heartbeat, radiographs for intra-fetal gas accumulation or abnormal skeletal arrangements, reflexes (suckle, anal tone, sublingual pulse)
- check for uterine torsion
Before deciding on medical treatment of dystocia, what 2 things should be done?
- radiographs - determine fetal number as well as malposition or fetal-maternal mismatch
- U/S - fetal viability and presence of distress
(if obstruction is present, do NOT give ecbolics)
What are the 2 major medical treatments of dystocia?
- oxytocin - NEVER given with obstruction, microdoses recommended, move onto C-section if nothing is delivered with 3 doses repeated in 15-30 mins (SQ, IV, IM)
- calcium solutions - concurrent cardiac monitoring for arrhythmias, SQ given 5 mL per location every 4-6 hours
What lubricants are commonly used for resolving dystocia? What is avoided?
methylcellulose-based
polyethylene polymer-based (J-Lube) –> fatal peritonitis in mares
(administered through sterile nasogastric tube and pump)
What part of anatomy predisposed cows to dystocia? How is this approached?
oval shaped pelvic canal
- alternate by pulling one limb at a time to decrease diameter of shoulders
- hip lock - rotate calf 45 degreed to decrease diameter across the pelvis
How is recumbency used to resolve dystocia?
changed the angle of the pelvis to increase the functional diameter of the pelvic canal
- NOT done in chute, can’t get the cow out
How can it be determined if a fetus is in anterior or posterior presentation if a limb can be observed?
FORELIMB - first two movable joints (fetlock and carpus) flex in the same position
HINDLIMB - first two movable joints (fetlock and hock) flex in the opposite direction
What are possible causes of no palpable limbs or both forelimb and hindlimb seen in cases of dystocia?
NONE - true breech (posterior longitudinal presentation with a bilateral hip flexion), schistosomus reflexus, dorso-transverse presentation (dog sitting)
BOTH - multiple fetuses, schistosomus reflexus, ventro-transverse presentation
Repositioning unilateral carpal flexion:
retropulse fetus to gain space then pull on flexed carpus
Repositioning unilateral shoulder flexion:
How is a forced extraction done correctly? What tools can be used?
apply traction during abdominal contractions of the dam and constantly monitor progress
- hands
- clamps/forceps
- OB chains, straps - applied above and below fetlock
- head snare - behind ears, wedge in oral cavity
- mechanical extractor - calf jack
How are OB chains put on correctly?
place a loop above the fetlock and a half hitch around the pastern
- tie over the front to avoid pressure on tendons
- shorter chain = more power
What are 3 pros and 3 cons to performing fetotomy for dystocia?
PROS - avoids expense and risks of C-section, may prevent further trauma to dam through excessive traction, reduces the size of the fetus
CONS - lacerations to genital tract, time-consuming, infections to obstetrician or dam if fetus is septic, necrotic, or emphysematous
(dislocate joint for delivery, avoid breaking bones!)
What is a complete fetotomy?
dismembering an oversized fetus with 5-6 cuts
- not always necessary for delivery
What kind of fetotomy is recommended in mares? If the foal is dogsitting or breeched? Why?
partial –> use one cut to remove the head or one foreleg
more complicated cuts, consider a C-section
MM of mare’s vaginal and cervix are easily abraded and can form adhesions
What post-dystocia care is necessary?
- check for additional fetuses
- examine genitourinary tract for laceration, hemorrhage, and infection - recto-vaginal fistula, perineal laceration, necrotizing vaginitis, metritis
- examine fetal membranes, appropriate retained placental therapy
What are 4 risk factors for perineal laceration?
- first delivery
- unopened Caslick’s suture
- dystocia - foot-nape position
- delivery of large fetus
What are the 3 degrees of perineal lacerations?
1st DEGREE = skin and MM of dorsal commissure
2nd DEGREE = musculature of constrictor vulvae and perineal body
3rd DEGREE = complete disruption of vaginal vault and/or roof of the vestibule, rectal floor, and anal sphincter, and perineal septum/body
What are 3 membrane removal techniques used in mares?
- uterine lavage
- Burns’ technique - chorioallantois is distended with dilute povidone-iodine or saline solution for 15 to 30 minutes to facilitate release of microcotyledons from the endometrium
- umbilical vessel infusion
