3. Canine Parturition and Obstetrics Flashcards
questions for owners after breeding:
◦ Was tie witnessed?
◦ Where was the bitch at in her cycle?
Important to consider purpose of bitch:
◦ Breeding bitch vs pet
what should we do after breeding if the owners witnessed a tie and it just happened?
vaginal swab for cytology > look for semen; cornified cells
Progesterone test to determine where she is at in her cycle
> is she even fertile at this time
options for pregnancy termination in the bitch
◦ Keep the pregnancy & have the litter
◦ Spay
◦ Aglepristone (Alizin®)
◦ Prolactin inhibitors (cabergoline, bromocriptine)
◦ Prostaglandins (PGF2⍺ - Dinoprost = Lutalyse® or PGF2⍺ analogues – cloprostenol = Estrumate®)
what is aglepristone (Alizin)? how is it available?
– only available through emergency drug release (EDR) & $$$
◦ Progesterone receptor antagonist
◦ “Tricks” the uterus into thinking progesterone levels are low
what are Prolactin inhibitors (cabergoline, bromocriptine)? what do they do and when should they be given?
◦ Prolactin is luteotropic (supports the CLs)
>tx causes luteolysis
>progesterone levels decrease
>termination of pregnancy
◦ Needs to be given after 30 days of pregnancy
how do prostoglandins work to terminate pregnancy? how can we administer them? what are side effects? what are they commonly used in conjunction with and why?
◦ Causes luteolysis
◦ Multiple injections needed
◦ Side effects: hypersalivation, vomiting, diarrhea, micturition, panting, tachycardia–affects all smooth muscles
◦ Often used in combination with aglepristone, prolactin inhibitors > allows for lower doses = less side effects
◦ Used alone > very hard on the bitch
what is NOT recommended to be used for pregnancy termination? How would this treatment work and why should we avoid it?
◦ Estrogens > “Mis-mate” shot – early in pregnancy
◦ High incidence of pyometra following treatment; bone marrow suppression also possible
◦ Do NOT use this!!!!!!
recommended course of action if a mismating occurred with a breeding bitch:
◦ Recommend referral to veterinary clinic with EDR for Aglepristone
◦ Clinics in the US use prolactin inhibitors – hard to get Aglepristone
◦ Reiterate to client that Aglepristone is very expensive – how serious is he about breeding in the future?
reccomended course of action if a mismating occurred in a non-breeding bitch:
◦ Recommend spay.
why are prostoglandins alone not the best strategy for pregnancy termination?
Prostaglandins alone – lots of side effects, many treatments needed – not a great option
if we terminate a pregnancy early, what outward signs should we alert the client to? what about mid gestation? late gestation?
◦ Early in gestation > could see no outward signs of pregnancy termination (resorptions)
◦ Mid gestation could see vaginal discharge > abortion (embryos/fetuses too small to see)
◦ If late in gestation > could see actual fetuses > more difficult for clients to see this – termination should be initiated before this stage
hormonal changes during parturition and what instigates this cascade:
fetal stress (often due to the fetuses running out of room)
>increased fetal cortisol
> increased prostaglandin from placenta (increased maternal cortisol also contributes to this)
=>decreased progesterone (due to lysis of the CLs by prostaglandin)
=>uterine contractions (Oxytocin also contributes to this, along with increased prostaglandin)
As progesterone drops, it will cause more prostaglandin release, which further decreases progesterone…and we have a little feedback loop
> uterine contractions cause fetal pressure against the cervix, which then leads to more oxytocin release, which leads to more uterine contractions… another feedback loop, called Fegusson’s reflex
what important consideration related to fetal stress should we keep in mind for parturition? (think about singleton pregnancy)
Because dogs are a litter bearing species, they may not produce enough fetal cortisol to initiate the parturition cascade in cases of a singleton pregnancy.
what is Fergusson’s Reflex
oxytocin and prostaglandin cause uterine contractions, which increases fetal pressure against cervix, which causes the release of more oxytocin, which increases uterine contraction, which further increases fetal pressure against cervix…….. positive feedback loop
how is progesterone related to temperature? what are the consequences of this? what are progesterone levels that relate to the start of parturition?
Progesterone = hyperthermic hormone
◦ When P4 drops below 2ng/ml > labor begins in 12-36 hours
◦ Drop in P4 = drop in temperature
> Drop needs to be at least 1◦C (1.1◦C – 1.7◦C)
◦ Owners can monitor temperature to try to “catch” the
progesterone drop
> It is TRANSIENT – not always captured > importance of due dates!
Ideally:
◦ Have baseline values for 1-2 weeks prior to due date
◦ Take q8hrs-12hrs to try to capture the drop (2-3x daily)
what happens during stage one of labour? what is the most common clinical sign and what are some others? how long does this stage last?
Panting is the most common clinical sign of 1st stage labor. Is sometimes also the only sign present.
◦ Synchronous uterine contractions
> Not visible from the outside
◦ Cervical relaxation
◦ Typically lasts 6-12hrs but can last up to 36hrs in primiparous bitches
Other Clinical Signs:
◦ Anorexia
◦ Panting
◦ Shivering
◦ Restlessness
◦ Nesting
◦ Refusing to eat
what occurs during stage 2 of labour? what will we see?
◦ Expulsion of fetuses
◦ Fergusson’s Reflex
> Fetus in birth canal > stretching cervix, vagina, uterus > oxytocin release
◦ Visible abdominal contractions
◦ Allantochorion ruptures often during birth
◦ Allantoamnion often still covers pup at birth
◦ Uteroverdin
> Breakdown product of biliverdin from placental margins
during stage 2 of parturition, how long should we expect between pups? how long does this stage generally take?
◦ 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 of labour? when does it occur in bitches?
◦ Passage of fetal membranes
◦ Occurs concurrently with stage 2
◦ Can be passed with the puppy, or 5-15 mins after the pups
◦ Can have 2 pups before 1 placenta
◦ Retained placentas can occur. Rare, and typically do not cause issues.
what are presentation, posture, and position of pups during birth? what is normal?
Presentation
◦ Relationship of spinal axis of the fetus to that of the dam
◦ Longitudinal vs transverse
◦ Longitudinal cranial/caudal = normal
Posture
◦ Relationship of the fetal extremities or the head/neck to the body of the fetus
◦ Extended head and limbs = normal
Position
◦ 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
Means “difficult birth”
Risk factors:
◦ 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
Can be due to maternal and fetal causes
