Parturition and Obstetrics Flashcards
what are 5 options for pregnancy termination
-keep pregnancy and have litter
-spay
-aglepristone (alizin); only available through emergency drug release
-prolactin inhibitors; needs to be given after 30 days of pregnancy
-prostaglandins; causes luteolysis
how do prolactin inhibitors work
prolactin is luteotropic (supports CLs) -> tx causes luteolysis -> progesterone levels decrease -> termination of pregnancy
two names of prolactin inhibitors
cabergoline, bromocriptine
how does aglepristone work
progesterone receptor antagonist, tricks uterus into thinking progesterone levels are low
what do you need to be aware of if using prostaglandins to terminate pregnancy (how many injections, side effects)
-multiple injections needed
-side effects; hypersalivation, vomiting, diarrhea, micturition, panting, tachycardia (affects all smooth muscles)
what are prostaglandins used in combination with and why
with algepristone or prolactin inhibitors. allows for lower doses and therefore less side effecs
if used alone its very hard on the bitch
why is a mismate shot not recommended as pregnancy termination
high incidence of pyometra following treatment, bone marrow suppression also possible. never use it!
what can you expect to see if there is pregnancy termination during early, mid and late gestation
-early; could see no outward signs of pregnancy termination (resorptions)
-mid gestation could see vaginal discharge; abortion (embryos/fetuses too small to see)
-late; could see actual fetuses; more difficult for clients to see this so it should be terminated before this point if possible
what can you expect when P4 drops below 2ng/mL
labour beings in 12-36 hours
what happens when P4 drops temperature wise
temperature…. drop by at least 1C to expect parturition
what is the most common clinical sign of first stage labour
panting! sometimes its the only clinical sign present
what happens during phase 1 of labour? how long does it last?
-synchronous uterine contractions; not visible from the outside
-cervical relaxation
-typically lassts 6-12 hours but can last up to 36 hours in primiparous bitches
clinical signs during stage 1 of labour
◦ Anorexia
◦ Panting
◦ Shivering
◦ Restlessness
◦ Nesting
◦ Refusing to eat
steps in fergussons reflex
◦ Fetus in birth canal → stretching cervix, vagina, uterus → oxytocin release
what happens during stage 2 of labour
◦ Expulsion of fetuses
◦ Fergusson’s Reflex
◦ Visible abdominal contractions
◦ Allantochorion ruptures often during birth
what often ruptures during birth (stage 2)
◦ Allantochorion ruptures often during birth
what often covers pups at birth
◦ Allantoamnion often still covers pup at birth
what is uteroverdin
◦ Breakdown product of biliverdin from placental margins
what is normal timing for the entirety of parturition, and time between pups
◦ Usually 1 pup every 30 mins – 1 hr
◦ Can go up to 3-4 hrs between pups in some cases*
◦ Usually have all pups born within 6hrs but can go up to 24hrs in large litters
what happens during stage 3 and when does it occur
◦ Passage of fetal membranes
◦ Occurs concurrently with stage 2
how long should stage 3 take
◦ Can be passed with the puppy, or 5-15 mins after the pups
◦ Can have 2 pups before 1 placenta
are retained placentas common in dogs
no they are rare
what is presentation relating to and what is normal in dogs
◦ Relationship of spinal axis of the fetus to that of the dam
◦ Longitudinal vs transverse
◦ Longitudinal cranial/caudal = normal
what is posture relating to and what is normal in dogs
◦ Relationship of the fetal extremities or the head/neck to the body of the fetus
◦ Extended head and limbs = normal
what is position relating to and what is normal in dogs
◦ Relationship of the dorsum of the fetus in a longitudinal presentation, or the head of the fetus in a transverse presentation to the quadrants of the maternal pelvis
◦ Dorsosacral = normal
risk factors for dystocia (5)
◦ Age of bitch (>6 years = associated with greater risk; especially if 1st litter)
◦ Parity (how many litters the bitch has had)
◦ Bitch breed
◦ Bitch weight
◦ Litter size
is dystocia due to materal or fetal factors
can be due to either!
what doesnt occur in cases of interia
no fergusson reflex occurs bc uterus fails to respond to oxytocin
what happens with primary uterine inertia
◦ No sign of 2nd stage labor – never have delivery of a puppy
◦ Partial primary inertia = contractions start and stop without passage of a puppy
◦ Partial dilation of the cervix
what are some causes of primary uterine inertia (4)
◦ Genetic (terrier breeds)
◦ Large litter – stretching of the
uterus
◦ Inadequate stretching with 1-2 pup litters
◦ Hypocalcemia + other signs of systemic illness
what happens with secondary uterine inertia
◦ Passage of 1 or more pups
◦ Prolonged uterine contractions fail to expel a pup
what are some causes of secondary uterine inertia (3)
◦ Can occur for similar reasons as primary uterine inertia
◦ Can occur in large litters
◦ Can occur if a fetus is obstructing pelvic canal
what are 3 general maternal factors for dystocia
-breed (brachycephalics)
-conformation
-maternal illness
what are some materal issues related to confirmation that leads to dystocia (5)
◦ Persistent hymen
◦ Vaginal septum
◦ Tumors
◦ Vaginal prolapse
◦ Uterine torsion
maternal illnesses that can lead to dystocia (2)
-parasitism
-malnutrition
general fetal factors leading to dystocia (3)
-presentation/posture/position
-abnormal fetal development
-fetal oversize
types of abnormal fetal development that leads to dystocia (5)
◦ Abnormal number of limbs
◦ Thoracic/abdominal hernias, omphalocele
◦ Fetal monsters
◦ Hydrops fetalis/fetal anasarca
◦ Anencephaly
how can fetal oversize happen
singleton litters
issues related to presentation/position/posture that leads to dystocia
◦ Caudal longitudinal – failure to engage the cervix
◦ Breech
when to communicate with the client when to call you (the vet)!!!!!! (11)
◦ Gestation length > known due date based on ovulation timing
◦ Gestation length > 70 days from breeding date
◦ >60 days from 1st day of cytological diestrus
◦ If haven’t whelped 24hrs past temperature drop = overdue
◦ If bitch is really straining for over 30 minutes with no pup produced
◦ Unproductive straining with pup in canal for >15 mins
◦ Weak, intermittent, abdominal contractions for >3 hrs without a pup; > 3hrs since birth of last pup
◦ Presence of lochia/uteroverdin & no signs of labor
◦ Stage 2 has been going on for longer than 18 hours (8-12 hours for valuable litters)
◦ Any sign of maternal distress or signs of maternal illness
◦ Any owner concerns
steps in dystocia management (6)
-history
-PE
-fetal HR on ultrasound
-rads
-whelp wise
-blood gas, CBC, biochemistry
two aspects that must be included in the PE of dystocia management
◦ Including mammary gland evaluation – presence of milk?
◦ Vaginal palpation
what does low fetal HR tell you on U/S
low HR = low oxygen
what can rads tell you during dystocia cases (2)
◦ Fetal death
◦ Obstruction
two parameters to look for from blood gas/CBC/biochem
◦ Glucose, calcium
what % of dystocias result in C-sections
60-80%
what three things are you trying to determine in dystocia management
- If there’s an actual pregnancy present?
- What’s the cause of the dystocia?
- Is there maternal or fetal compromise?
medical management should only be considered IF (6)
- Bitch is in good health
- Labor has not been going for too long
- Cervix is dilated
- Fetal size is appropriate
- FHRs are normal
- NO obstructive dystocia present
what are ecbolic drugs
drugs that cause uterine contractions
doses of oxytocin for medical management
0.5-2 U SQ q30 minutes
doses of calcium for medical management
0.2mL/kg of 10% IV or 1-5mLs SQ
what is the max amount of doses of oxytocin you can give to a dog for medical management of dystocia
no more than 2 doses!!!!
when should you NOT use ecbolic drugs
never use in obstructive dystocias
what does oxytocin do and what happens if too high of a dose is given
◦ Increases frequency of uterine contractions
◦ Uterine hyperstimulation & fetal distress + uterine tetany if too high a dose is given
what does calcium do and how can you use it
◦ Increases strength of uterine contractions
◦ Calcium ions = necessary for myometrial contractions
◦ Can be used alone or with oxytocin
◦ Low levels and normal levels of calcium
what do you need to ensure you do if you give calcium IV
give it SLOW and listen for arrythmias
what to do with mechanical management
-lots of lube
-digital manipulation; fingers are the best tool with cloth sponge
-go with the ischial arch
-instruments (spay hooks, sponge forceps, clamshell forceps)
what do you need to be aware of with instruments and why
Very careful – can crush skulls, paws, quite easily
5 indications for surgical management of dystocia
◦ Low fetal heart rate (<150bpm; sustained = emergency; 150-170bpm = moderate to severe fetal stress)
◦ Obstructive dystocia
◦ Primary & secondary uterine inertia
◦ Uterine rupture or torsion
◦ No response to medical management
what do you always need to do prior to surgical management of dystocia
Always do a radiograph just prior to surgery to ensure there are still puppies to be delivered!!
what is important to do with the mom during surgical management of dystocia
Important to stabilize mom (fluids, correct metabolic issues) if needed
two goals of C sections in dystocia cases
◦ Want to minimize fetal respiratory, CNS and cardiovascular depression (Deliver live pups)
◦ Maximize mom’s anesthesia & analgesia (Limit complications for mom: hypotension, hypoventilation, hypoxemia, hemorrhage, hypothermia)
5 things to consider for c sections
◦ Changes in bitch’s blood pressure (due to pain, stress, hyperventilation) → decreased blood flow to uterus → fetal hypoxia
◦ Bitches’ have increased oxygen consumption → increased risk of hypoxia → PRE-OXYGENATE!!!
◦ Increased blood flow to uterus → increased risk of hemorrhage
◦ Bitches’ are more likely to regurgitate under general anesthesia
◦ Most drugs that cross blood-brain barrier also cross placenta
ideal c section drug protcols! (5)
- Pre-oxygenate mom
- Induction with alphaxalone
- Isoflurane or sevoflurane for
inhaled anesthetic - Butorphanol for pain until pups
are out, then hydromorphine - +/- epidural or local anesthetic
best options for inhaled anesthetics for c sections
iso and sevo
what do you NOT use during c sections
dont use tranquilizers and sedatives
best c sections approach; how to do it, make sure you do what
Ventral midline
◦ Milk puppies through 1 uterine incision, might need more than 1 incision
◦ Make sure you palpate the entire uterus up to the ovaries
why is c section spay approach not recommended
◦ Increased risk of hemorrhage & hypovolemic shock
◦ Lactation is normal
◦ Might be necessary in some instances; but not recommended
why is en bloc approach to c section not recommended and how is it done
◦ Clamp uterine and ovarian vessels and ligate
◦ Remove entire uterus at once
◦ Risk – too slow → pups have no blood source
◦ Not recommended
causes of fetal depression and what does it result in
◦ Due to hypoxia associated with dystocia
◦ Due to medications
◦ Results in slow HR, RR and movements
goals of neonatal resuscetation center on what (2)
◦ Oxygen delivery to tissues (clearing airway)
◦ Warming the pup
what does neonatal resuscitation include (5)
◦ Removal of fetal membranes and fluids from nose and mouth (Bulb syringe)
◦ Clamping of the umbilicus
◦ Rubbing puppies with warm towel – important to get them dry and warm
◦ Flow by oxygen as puppies start to gasp
◦ Naloxone (1-2 drops sublingual) if needed
how should pups respond to neonatal resuscitation
Pups should respond to this by taking frequent breaths, turning pink and vocalizing
what else can you try if normal steps in neonatal resusitation doesnt work (3)
◦ JenChung GV26 acupuncture point
◦ O2 mask
◦ Stimulating genitals for urination/defecation
what is usually prescribed in practice for c section post op meds
TRAMADOL
◦ Little effect to neonates that are nursing (based on human medicine)
◦ What is typically prescribed in practice
◦ Efficacy is controversial (dogs produce more of the weak analgesic metabolite; half life of good metabolite is very short)
when do canine kidneys mature and function normally
◦ Canine kidneys → maturation doesn’t occur until 3 weeks of age; normal function at 6-8 weeks
of age
does one c section make a dog predisposed to another c section in the future?
◦ Increased chance of requiring a c-section if they’ve had 1 already
~~Depends on the cause of requiring the c-section in the 1st place (Singleton litter vs uterine inertia, Predisposition to uterine inertia increases the chances of requiring a 2nd c-section?)
◦ Usually if they’ve had 2 → I recommend the third to be an elective
things to look for to determine if fetuses are ready for birth (2)
◦ Presence of milk
◦ Should ask owner regarding any signs of 1st stage labor
why is it important to determine if puppies are ready to be born (2)
◦ Premature puppies have a high mortality risk
◦ Canine placenta cannot support fetuses >2 days past whelping date → intra-uterine fetal death
ultrasound findings to determine if puppies are ready to come out (5)
◦ Signs of fetal distress (FHRs are taken)
◦ Appearance of fetal kidneys → similar to adult appearance (Can distinguish cortex from medulla, Renal pelvises become less dilated at term)
◦ Appearance of fetal intestines → can distinguish between layers (serosa, mucosa, submucosa)
◦ Peristalsis is present @ term
◦ Biparietal diameter – anecdotal finding
