Whelping and dystocia Flashcards
Primary uterine inertia
- progesterone falls (stage of preparation)
- uterine contractions commence (1st stage parturition occurs but may be weak)
- uterine contractions cease
- abdominal contractions don’t occur (no 2nd stage parturition)
- ultimately placentas separate (green discharge from marginal region of placenta)
- foetuses die
Primary uterine inertia - risk factors
- small litter
- large litter
- old dam
- obese dam
- debilitated dam
Monitoring bitches at risk of primary inertia - methods
Progesterone concentration
- 1st progesterone less than 2.0ng/ml (≈6nmol/l) associated with parturition within max of 26h
(- 1st progesterone <3.0ng/ml = parturition in max 50h)
Rectal temp & progesterone
- rectal temp decrease by 1C between 10-14h after progesterone decrease to less than 2ng/ml
- 1st rectal temp less than 37C is associated with parturition within max of 38h
Endoscopic appearance of cervix
Day -10:
- Os closed
- tacky clear mucus
Day -7:
- larger volumes of clear mucus
- vaginal wall oedema
- increased vascularisation of vagina
Day -1:
- slight opening and increased mucoid discharge noted at -6h
CE regime at term - at the time of presentation of a presumed overdue bitch / case of primary inertia / obvious case of dystocia, what information can be helpful?
- mating dates and other info relating to oestrus
- general CE
- digital/endoscopic exam
- US exam
- radiographic exam
- measurement of plasma progesterone
Tx options when inertia has occurred but before the pups have died
Oxytocin
- doses are often too high and cause tetany not coordinated contractions
- 0.04IU/kg is appropriate given q30mins for 3 doses
- oxytocin compresses placenta and worsens foetal hypoxia so is contraindicated if foetuses are bradycardic
Calcium
- concurrent calcium administration improves uterine contractions
- 20% calcium glutinate diluted 1:7 (= 2.5%)
- 1.0ml/kg SC of 2.5% solution
How to stimulate milk production
Prolactin agonists
= dopamine antagonists
- metoclopramide at 0.1-0.2mg/kg SC TID/QID
- phenothiazines at low dose may also stimulate mild production
Foetal HR & what it indicates
Normal HR at term
- 170-230bpm
- or at least 4x maternal
- transient increase with foetal movement
HR <150bpm
- indicates stress (hypoxia)
HR <130bpm
- poor survival if not delivered within 2-3h
HR <100bpm
- immediate (medical or surgical) intervention needed before demise of pups
Pups prognosis when delivered before expected due date
- pups delivered 48h before expected due date can survive without any particular intensive support
– likely bc lung surfactant has already been produced at this time
Incidence of c-sections in brachys
- 92.3% in Boston terriers
- 86.1% in Bulldogs/British bulldogs
- 81.3% in French bulldogs
Ways to predict parturition
- using information collected at time of mating
- using embryo/foetal measurements
- using embryo/foetal assessment
Predicting parturition using info collected at the time of mating
Onset of parturition is consistently 63±1d from ovulation
Markers of ovulation are useful:
- progesterone ≈ 2.5ng/l (8nmol/l) at LH surge
- progesterone ≈ 7ng/ml (21nmol/l) at ovulation
- progesterone ≈ 10ng/ml (32nmol/l) 2d after ovulation
- progesterone ≈ 25ng/ml (80nmol/l) at the end of the fertilisation period
Predicting parturition using embryo/foetal measurements
Examples:
- gestational sac diameter
- head diameter
Gestational age = (6 x gestational sac diameter [cm] + 20)
Gestational age = (15 x head diameter [cm] + 20)
Days to parturition = 63 - gestational age
NB these measurements are size/breed specific
- small breeds (<9kg) + 1d to calculated GA
- giant breeds (>40kg) - 2d from calculated GA
Predicting parturition using embryo/foetal assessment
Examples:
- detect of specific characteristics of the pregnancy
- 1st appearance of the embryo proper
- regression of the yolk sac
- ^ these parameters are consistent across breeds
- detection of organ development
– detection of urinary bladder = 37d after ovulation
– detection of kidneys = 39-47d after ovulation
– detection of eyes = 40-47d after ovulation
– detection of individual cardiac chambers = 40d after ovulation
– detection of intestines = 59d after ovulation
Normal parturition (stage of preparation) - what happens
Normal parturition (1st stage parturition) - what happens
- onset of uterine (not abdominal) contractions
– bitch restless, pants, anorexic - pup pushed against cervix
– cervix dilates
– outer membrane may break -> fluid seen at vulva - 1-12h in duration
- milk present in mammary gland
What is the earliest sign of foetal death on a radiograph?
- intra-vascular gas
