dystocia Flashcards
what is dystocia in cattle?
difficult or prolonged birth that may or may not require human assistance
describe the 3 stages of parturition in cattle briefly
stage 1: relaxation and dilation of the cervix, rupture of the chorioallantois and membrane
stage 2: passing of the fetus through the birth canal
stage 3: expulsion of fetal membranes
tell me how hormones prime the cow for onset of parturition
- fetal adrenal glands release cortisol
- increase 17alpha hydroxylase in placenta
- decreases progesterone
- converts pregnenolone to estrogens
- increasing PGF2alpha myometrium contractions
how long does stage 1 of parturition last in the cow?
8-12 hours
during stage 1 parturition in the cow, how is dilation of the cervix achieved?
decreasing cervical tone, absence of progesterone, mechanical pressure form fetus
during stage 1 parturition in the cow, how are myometrial contractions initiated
pressure synapse release oxytocin
how long does stage 2 parturition last in the cow?
1-4 hours
during stage 3 parturition in the cow, how does detachment of the placenta occur?
via vasoconstriction and myometrial contractions, which dislodge the chorionic villi from the crypts
how long does stage 3 parturition last in the cow?
12 hours
true or false: a stage 3 lasting >24 hours in the cow is considered pathologic
true
briefly tell me fetal blood circulation in utero
umbilical vein –> portal vein (ductus venosus) –> caudal VC –> RA –> LA foramen ovale –> LV –> aorta –> umbilical arteries –> pulmonary artery (ductuc arteriosus) –> aorta
tell me how fetal blood circulation changes with rupture of the umbilical cord?
rupture of umbilical cord –> asphyxia –> gasping reflexes –> increased peripheral vascular resistance –> lung inflation –> increased O2 tension –> ductus arteriosus closes –> increase BP –> closure of foramen ovale
rupture of the umbilical cord leads to a ________ (acid base dysfunction)
transient mild mixed acidosis
rupture of the umbilical cord leads to a transient mild mixed acidosis. tell me the 2 components of a mixed acidosis and why it’s caused in this case
metabolic acidosis: anaerobic glycolysis initiated by poorly perfused tissues
resp acidosis: asphyxia and build up of CO2
lactic acidosis caused by anaerobic glycolysis and poor tissue perfusion
what are the problems with acidosis at birth?
- increased risk of failed transfer of passive immunity
- increased risk of pre-weaning morbidity and mortality
what are the behavioural indicators of dystocia?
- restlessness
- prolonged lying time
- longer duration of tail elevation
- reduced abdominal contractions
- prolonged time b/t visualization of amniotic sac to birth of the calf
true or false: dystocia is more common in beef cattle than dairy cattle
false!
incidence in beef cattle: 5-15%
incidence in dairy cattle: 15-30%
tell me some dam risk factors for dystocia
- heifer
- high birth weight
- low BCS as a yearling dam
- low or high BCS at calving
- mineral deficiencies
- confinement
tell me some neonate risk factors for dystocia
- male –> larger body dimensions and higher birth weight
- twins –> malpresentation or malposture
- high birth weight –> larger –> fetal maternal size mismatch
tell me some ways to decrease the risk of dystocia
- heifer selection
- dam nutrition
- sire selection for birthweight and calving ease
- pelvic abnormalities
name 3 causes of dystocia that are maternal in origin
- primary uterine inertia
- secondary uterine inertia
- abnormalities of the birth canal
name 3 causes of dystocia that are fetal in origin
- abnormal P’s (presentation, posture, position)
- large offspring (fetal oversize or large offspring syndrome)
- fetal monsters (deformities)
what is primary uterine inertia?
failure of the myometrium to contract
what is secondary uterine inertia?
exhaustion of the myometrium after a prolonged parturition
what causes primary uterine inertia?
- overstretching of the uterus by multiple fetuses
- defect in the myometrium
- defect in the parturient hormones
- muscular atony caused by post parturient hypocalcemia
tell me some abnormalities of the birth canal that can cause dystocia.
- small maternal pelvis
- pelvic deformities
- incomplete dilation of the cervix
- remnants of the mullarian ducts
- uterine torsions 5-10%
what are the causes/risk factors of uterine torsion?
- multiple fetuses
- walking up hills
- poor muscle tone
- enlarged rumen
- breed = brown swiss
how do you tx uterine torsions?
- “plank in the flank” –> laterally recumbent animal has plank on flank to hold uterus still, person stands on plank and animal is rolled in the direction of the torsion
- c-section
- detorsion rod
50% of dystocias are caused by ____?
fetal maternal size mismatch
the odds of fetal maternal size mismatch causing dystocia increase by 13x by every _____kg increase in birthweight
1
fetal maternal size mismatches are more common in _____
heifers
fetal material size mismatches are the result of what?
mismanagement of heifers and bull selection
what are the 3 P’s?
presentation, position, posture
what is presentation? what is normal?
relation of the spinal axis of the fetus to the dam’s axis
which part of the calf is being presented for delivery
anterior, posterior, transverse
normal: anterior
what is position? what is normal?
relation of the dorsum of the fetus to the quadrants of the material pelvis
dorsosacral
dorsopubic
dorsoilliac
normal: dorsosacral
what is posture? what is normal?
relation of the fetal extremities to its own body
head ventroflexed
carpal flexion
hip bilaterally flexed (breech)
normal: both front legs and head presented in the birth canal
list the 3 P’s in order of most likely to cause dystocia to least likely
posture
presentation
position
when should you intervene in a cow birth?
- not making progress every 30-60 mins
- abnormal PPP (3 p’s)
- prolonged gestation date (only if accurate!)
what are the 3 therio rules? like very general
be clean, be gentle, and by god use LOTS AND LOTS OF LUBE
what equipment do you need in a dystocia case?
- bucket of warm water
- disinfectant
- lube (not J-lube)
- OB sleeves
- OB chains, handles, head snare, calf jack
- halter/ropes
what do you do to the cow to get ready to help with a dystocia?
- restrain
- tie tail
- rectal exam
- clean perineum
- vag exam with OB sleeves and lube
talk me through a vag exam of a cow with dystocia
- enter vag, ID cervix - note if fully dilated, obstructions, etc)
- enter uterus
- ID calf w/ 3 P’s
- ID if calf alive or dead - pull on tongue, pinch toes, palpebral reflex, anal reflex
tell me the broad steps of dealing with a dystocia case
- restrain, tie tail, etc
- rectal exam, clean perineum
- vag exam
- mutation
- make sure calf can fit
- get ready to pull
- PUUUULLLLLLLLL!!!!!!
what is mutation in terms of helping with dystocia?
fetus is restored to normal presentation, posture, and position by repulsion, rotation, version, or extension of extremities
what is repulsion when dealing with mutation?
push the fetus out of the maternal pelvis into the uterine cavity
what is rotation when dealing with mutation?
turning the fetus on its longitudinal axis to bring it to dorsosacral position
what is version when dealing with mutation?
turning the fetus on its transverse axis into anterior or posterior position
unlikely to correct
usually results in C-section
how can you make sure the calf will fit in the birth canal?
head and legs should be able to be advanced into the birth canal
hand should be able to go around calf when positioned in the birth canal
how do you get ready to pull a calf out of the vag?
2 limbs ± head are in normal position and belong to the same calf
apply OB chains above fetlock with half hitch below
how do you successfully and properly pull a calf outta its momma?
- pull only when cow contracts or pushes
- relax when cow relaxes
- pull one limb at a time (see-saw)
- once head and front limbs are out and chest is in birth canal, rotate calf 45 degrees to prevent hip lock
tell me some fun little helpful tools and tricks to assisting with dystocia
- epidurals prevent contractions
- oro-tracheal tube prevents abdominal contractions
- epi IM can relax ute ute to repulse and reposition
- casting cow down in lateral recumbence opens pelvis
what do eye hooks do?
direct the head
what does a head snare do?
directs the head
tell me some other options for calf removal other than pulling that bitch out of the vag
- C section
- fetotomy (if its dead already, obvi)
post delivery in the cow, what should you address?
- “spares and tears”
- pain mitigation
- ABs
- ± ecbolics
tell me important things to do right after calf leaves birth canal (post-calving calf care)
- sit calf in sternal recumbency
- ABC (airway, breathing, circulation)
how do you assess ABC in a newly born calf?
A: clear airway, resuscitation
B: rub vigorously, straw up nose
C: check heartbeat, give resuscitation drug
