Induction, Calving & Extractions Flashcards
any obstetrical event is
stressful
when faced with any obstetrical event consider…
the consequences of decisions/events (dam & foetus, economics)
When do you use Induction?
- to save life of the foetus or dam
- when gestation has progressed beyond the normal due date
why do we use induction?
- to manage parturition
- to save life of foetus or dam
- to prevent dystocia from an oversized foetus when gestation is past its normal due date
3 requirements around parturition induction
- viable foetus
- maternal delivery must NOT damage offspring
- dam must sustain neonate
What is the ideal situation for induction?
alive, not too difficult to remove, availability of colostrum
Clinical indications for induction
- anticipation of relatively oversized foetus
- single foetus (in multipara species)
- illness of the dam
- mummified foetus, hydrops allantois, etc.
Management indications for induction examples
- parturition in presence of skilled assistance (sows)
- batch calving (beef cows)
Corticosteroids are most commonly used as induction agents in what group of species?
ruminants
Prostaglandins are considered
luteolytic
Prostaglandins are commonly used in ruminants except they are not effective in…
sheep
Anti-progesterone agents are most commonly used in what species
bitches
most large animals get what induction agents?
steroids, prostaglandins or both
What stimulation agents can be used for established parturition?
- Calcium +/- Magnesium
- Oxytocin
- Prostaglandins
Avg gestation in a mare
340 days (range 320-365 days)
the window of viability in foals is…
narrow
foetal maturity in foals cannot be predicted by…
gestational length
indications for foaling
- waxing
- changes in milk composition
What are the expected changes in milk composition prior to foaling?
- Ca > 40 mg/dl (Ca rises)
- Na falls 120 mg/dl to 10 mg/dl (Na falls)
- K rises to 20 mg/dl (K rises)
When should you induce foaling?
near term b/c of the window of viability
Why might you use prostaglandins during foaling?
muscular action
what is the risk of using prostaglandins during foaling?
danger of uterine rupture
When could oxytocin be used in foaling?
at the end of pregnancy by drip or injection
What is important to know about the use of oxytocin during foaling?
Doses of <60 IU may result in retained foetal membranes (RFM)
When/how could dexamethasone be used in foaling?
100 mg/day for 4 days starting at Day 321
Dexamethasone during foaling is not recommended when?
- standard foaling process
- sick mares (occasionally)
It is important to note the side effects of which drugs during induction of foaling
Prostaglandins, Oxytocin, Dexamethasone
when do foals do their final rotation?
in the last stage of foaling just prior to parturition
if induction/interruption occurs during a foal’s final rotation, what can occur?
Dystocia
What is the drug of choice for induction of foaling?
Oxytocin
When can prostaglandins be used for foaling induction?
On/after Day 330 if pelvic relaxation has occurred
When do you use corticosteroids to induce foaling in mares?
NEVER
gestation length of Holstein/Friestians
278 days
Gestation length of Aberdeen Angus
279 days
Gestation length of short horn
282 days
Gestation length of herefords
285 days
Gestation length of limousins
286 days
gestation length of Charolais
290 days
in cattle different breeds have different
gestation lengths
What occurs in the last week of gestation in cattle?
Rapid foetal growth (1 kg/day)
Premature induction can reduce the likelihood of dystocia in cattle but what should you be aware of when considering this?
- gestation length differences
- calf weight
The stage of induction compromises between what 2 factors in cattle?
Viable weight of calf & the weight at which the calf would need assistance during birth
What is the viable calf weight for aberdeen angus & Hereford calves?
40 kg
What is the viable weight of a Friesian calf?
42-45 kg
What is the viable weight of a Charolais calf?
35-45 kg
In cattle, induction prior to Day 270 results in
an unviable calf
What drugs could POTENTIALLY be used to induce parturition in cattle?
- Prostaglandin - PGF2alpha
- Corticosteroids
- PGF + steroid
what are concerns with giving PGF2alpha to induce cattle?
- Given prior to Day 270 = dystocia (worse in heifers)
- Explosive expulsions possible
- high incidence of malpresentation (lack of rotation)
- High incidence of RFM
What are concerns with giving corticosteroids to induce cattle?
- high incidence of RFM
- immunosuppressive
Why might you choose corticosteroids over PGF2alpha to induce cattle?
- calf maturation better (= higher survival rate)
- better maternal tract preparation
- better initiation of lactation
- better bonding in beef cattle
What is the most common way of inducing cattle?
PGF + steroids
What are the combinations of treatment for induction of calving?
- Long-acting steroid
- long-acting steroid 10-14 days before term, then short-acting steroid OR PG 8 days later
- short-acting steroid + PG
how quickly does calving occur after proper induction?
48-72 hours later
when are sheep induced?
twin lamb dz mainly
if induction in sheep were used what is extremely important to remember?
their gestation period is relatively short so the EXACT DATE OF SERVICE IS NECESSARY
What medication is an option inducing sheep?
Corticosteroids
how far into pregnancy should you induce sheep?
Day 137 onwards BUT Day 142 or later ideally to increase chance of live foetus & minimise chance of death
How do you give sheep their induction agent?
Single IM injection 6 days before their due date
if sheep are induced, how quickly will it take them to lamb?
2-3 days
What medication can be used in sheep to cause abortion? when?
Prostaglandin until Day 55
on average how many piglets are born stillborn?
5-7%
how do you decrease stillborn deaths in sows?
supervision (greater care & attention at farrowing)
how do you induce sows?
Prostaglandin on Days 112-113 between 8 and 10 am to farrow the following afternoon
Why is induction of multiple sows at a time a potential benefit?
you can swap around piglets to give them all better chances of surviving
what are other options of assisting induction in sows?
- oxytocin 24 hrs post-PG injection to reduce interval to farrow
- Corticosteroids 75-100 mg SID on Days 101-104 to farrow on Day 109
Why are corticosteroids not actually used to induce sows?
poor survival rate of the piglets
how and when do you induce bitches?
At term w/ oxytocin
or using aglepristone (anti-progesterone agent)
What are things that must be done prior to induction of a bitch?
- exam to ensure ready for whelping (vaginal exam)
- exam to ensure no obstructive dystocias
how do you delay parturition? In what species can this be done?
- cows/heifers, sows, ewes
- Clenbuterol + Oxytocin
What are the 3 stages of Parturition
- opening of the cervix
- expulsion of the foetus
- expulsion of the foetal membranes
What general history of the dam should you know prior to parturition?
- previous parturitions incl trauma
- insemination/breeding date
- type of sire
- any illnesses during pregnancy
- how long into parturition (if at all)
- what has been tried/done so far & to what extent
What necessary equipment should you have for large animal parturition
- (clean calving jack)
- clean calving gown
- calving ropes/chains
- gloves
- lubricant
- disinfectant
what other useful equipment might be handy for parturition?
- oxytocin
- Planipart/Clenbuterol
- Caesarean kit
- Foetotomy wire
- local anaesthetic
- sedation
- bottle of calcium
- halter & nose tongs
- ropes
what should you look at on the dam externally prior to parturition?
- is she BAR?
- standing/lying/forcing?
- Are foetal parts visible?
- Are there any unusual smells?
- Behaviour of the dam/people around you
How might you create good working circumstances for yourself during parturition?
- space
- restraining options handy
- straw/towels for calf/foetus
- cold water
What should you check internally during parturition, especially if assistance is required?
- Any possible lesions (verbalise these)
- opening of the cervix
- foetal membranes & amniotic fluid
- poisition of uterus & foetus
- stage of contraction of the uterus
- signs of life from foetus (claw/foot/tongue withdrawal; blinking eyes; rectal tone)
- position of the umbilical cord
- type of foetus (muscular vs non-muscular)
- relative size of foetus to dam
- opening of soft parts of birth canal
What are the 4 structures the foetus has to pass thru?
- cervix
- pelvic brim
- vestibulo-vaginal jxn
- vulva
What is important to remember about using ropes/chains during parturition?
- noose AROUND the ears
- leg ropes/tractions in direction of the long bone at the knot & consider the amount of traction applied
it helps when extracting to remember to turn a calf
60 degrees to fit through the canal better upon extraction
What is important to remember if a calf presents backwards?
- time critical b/c nose in amniotic fluid & will have short amount of time to survive if the umbilical breaks
- remember to turn +/- 60 degrees until hips turned up near spinal canal instead of parallel to hips
When should you go for a c-section?
- if you cannot get arm/hand btw head & pelvis during extraction (large animals)
- if animal is tight at the front (shoulders), it will be worse at the pelvis of the foetus
- if trial traction feels EXTREMELY tight
