Week 4 Flashcards
What are some risks to prematurity?
* Stillborn
* Small, weak, sickly
* Failure to grow
* Asynchrony with colostrum
* Reduction in milk production- Mother is not ready to produce enough milk
Reasons for induction of parturition in late gestation
* For medical reasons- saving the mother or neonate
* As a management tool- especially in production animals
Induction of parturition late gestation as a management tool
* Synchronize calving in dairy herds
* Enhanced supervision of high value offspring
* Batch farrowing in sows
* Facilitate cross mothering in sows
* Concentrate labour efforts- if supervision is required, may not want to pay 1.5 rate on a Sunday to labour
* Observe parturition- difficulties expected
Induction of parturition in late gestation for medical reasons- high risk pregnancy
* Undesirable pregnancy of heifer
* Ruptured prepubic tendon
* Excessive udder oedema
* Maternal disease- HypoCa, Preg Tox, Hydrops…
* Prolonged gestation in cows- uncommon, a lot of variation in gestational length anyway
* Neonatal isoerythrolysis (NI) foals
How do you induce in a cow?
* Short acting dexamethasone- within 10 days of term, 90% calve in 45 hours +/- 5 hours; PG: calve in 1-4 days
* Long acting dexamethasone- 25-30 mg DexTMA (Trimedexil); second short acting dex or PG 10-12 days later; most calve within 1-3 days of second shot; calve more quickly as pregnancy progresses
* Prostaglandin- higher incidence of retained foetal membranes (RFM)- failure of placental detachment- it works, knocking out CL but prostaglandin leads to more complications at this very late stage
Downsides of induction of parturition in cows
* 5% decreased milk production
* High incidence of retained foetal membranes (RFM)
* Significant incidence of toxic metritis
* High calf mortality- stillbirths or non-viable
* Reproductive performance unaltered
Induction in late gestation in ewes
* Short acting corticosteroids
* 70-90% lamb in 1-3 days
* efficiency declines before day 140
* Oestrogens and PG not used
Reasons for mare inductions
* Must have severe life threatening risk to mare or foal
* fractured pelvis, previous NI foal, ruptured prepubic tendon, repeated stillborn foals, EHVI in foaling unit, Not udder oedema, Not prolonged gestation
Mare Induction criteria
> 330 days gestation, mare “bagged up”, cervix relaxed, prefoaling Ca levels in colostrum
Protocol for mare induction
Oxytocin- 5 IU iv and 40 IU im- wait 20 minutes and repeat; foal normally delivered within 1 hour; be in attendance with dystocia equipment
* lutalyse (dinoprost)- time of onset is variable and is associated with foal deaths
* Estrumate (fluprostenol)- safer but onset is still variable from 30 min to 3 hours
Downsides of induction of parturition in mares
* premature placental separation
* Maladjusted foals common
* Fractured ribs common- uncoordinated- breaks foals ribs
* Dystocias common- long spindly legs and long noses- so common if not in right position
Sow induction of parturition
* Program- 10 mg lutalyse i/m 8 am on day 112; by 1pm day 113- 5-30 IU of oxytocin and remaining sows will farrow within 3 hours
When are there few complications vs. likely complications with induction of abortion?
* Early Embryonic Loss- natural or induced early pregnancy- few complications
* Abortion mid gestation- complications likely: failure of abortion, require multiple treatments, risk of dystocia, increased risks of RFM, metritis, delayed uterine involution
Indications for Abortion
* Misalliance- female too young (in calf way too young), wrong sire (running a stud herd), bred out of season
* Female entering feedlot
* Reproductive pathology
* Fractured pelvis
* Ruptured prepubic tendon
* Excessive udder oedema
* Mare with twins
Cow abortion protocol
* PGF2alpha- 5 days after end of oestrus (comes into oestrus in 3-5 days, but takes up to 10 days to abort); 100% reliable during first 5 months; unreliable between 5-8 months gestation— to preg test or not to preg test? May not want to wait long enough until positive (?) so just use prostaglandin as cost is low
* PGF2alpha plus short acting corticosteroids- effective between 5-9 months, animals abort in about 5 days, risk of RFMs, dystocia and metritis
* Manual enucleation of CL- outdated technique; performed up to 4 months gestation; risk of adhesions, haemorrhage and decreased fertility
* Manual crushing of foetus- limited to 30-100 days, not recommended due to potential damage and trauma to the uterus
Mare abortion protocol
* PGF2alpha- method of choice, single injection up to day 35, multiple injections up to 5 days after day 35
* Cervical dilation and intrauterine infusion of saline, tetracycline, dilute iodine- significant risk of dystocia after 7 months
* Manual dilation of cervix with or without oxytocin and removal of foetus not recommended after 7 months
Ewe abortion protocol
* PGF2 alpha- effective during the first 50 days of gestation
* Corticosteroids- not highly effective until late gestation
Doe Abortion Protocol, same as Sow Abortion Protocol
* Prostaglandin (PGF2alpha)- single dose effective throughout pregnancy at inducing abortion and parturition
Bitch/Queen Abortion Protocol
* Limited options- most methods used in other species are poorly effective or are associated with unacceptable degrees of side effects in dogs and cats
* Aglepristone (Alizin) is registered in Australia for induction of abortion in the bitch from 0-45 days after mating
What are some indicators of impending parturition?
* Lowered body temperature (and behavioural changes)
* Further out- udder/vulva and pelvic changes (waxing udders in mare)
* Progesterone levels decline
* Calcium levels in mares’ milk spike
What are some warning devices for mare parturition?
* Foaling alarms e.g. Breed-ezy–> if mare lies down, sensitive but not specific
* Vulval devices- more sensitive and specific- only time it goes off when vulval opens
* Foaling cameras
* Foal watch crew
What are the three classic stages of parturition?
* Stage I: Cervical dilation, foetal positioning for expulsion– restlessness, frequent urination (responding to discomfort)– might be up to 1-2 days in heifers or just a few hours in other species
* Stage II: Starts with rupture of chorioallantois and ends in expulsion
* Stage III: Ends when foetal membranes are passed in their entirety
Stage I in bitches and queens
* 6 to 12 hours
* nesting behaviour, restlessness, vomiting, anorexia, shivering, cervical dilation, vaginal relaxation, uterine contractions
What drives parturition?
What causes the uterus to contract for parturition?
What are some criteria for a mare to be ready for a normal birth?
* Pelvic ligaments relaxed
* Full udder; waxing
* Gestation > 320 days
* Milk Ca increases 24 to 28 hours pre-partum
Stage I in a mare-normal parturition?
1-4 hours: restlessness, frequent urination, defecation, may sweat, may lay down
** Vital not to intervene too early
Stage II and III in a mare- normal parturition
* Stage II- 5-20 minutes: starts with rupture of chorioallantois rapid EXPLOSIVE delivery: if > 60 minutes foal likely to die
* Stage III: ends when foetal membranes are passed in their entirety
What species might you be a bit quicker to intervene?
Ewes. If an ewe has been straining for over an hour, perhaps tim eot intervene. Always check for a second lamb before suturing with caesarean- they can be tangled up, can be a cause of dystocia
Farrowing
* Sow nests about 72 hours prior
* Restless, pelvis drops, about -8 hours milk spurts, about -30 minutes respiration rate increases, tail wags, stage II, pigs appear at about 12-25 minute intervals, farrowing takes about 3-5 hours
** Stage II 1-5 hours
* Oxytocin often administered +/- Ca
Stage II in a Queen
Average duration: 8 hours, range 4- 42 hours
* stages are the same as in the bitch
* Dystocia is uncommon- usually a kitten will be dead
Whelping bitch stage II
4-6 hours (up to 12- 24 hours in some normal bitches)
* expulsion of first pups can last up to 4 hours, usually 30 min- 2 hours in between pups
(may take a break)
* Note dark green pigment of placenta
What to do with obstructive dystocia?
Vaginal exam, ultrasonography, radiology
Indications for surgical management of dystocia in bitch/queen- Caesarean
Generally rule out obstructive dystocia– supportive treatment– if still not working– caesarean
* Complete, partial primary or secondary uterine inertia with a poor response to treatment (oxytocin and Ca common)
* fetal oversize or malformation
* maternal pelvic obstruction (e.g. fractures, masses)
* Non-reducible malpresentations
* Past history of dystocia or caesarean section
* fetal distress
* Systemic illness of the bitch/queen
* Suspected uterine torsion/rupture/prolapse or herniation
Calving intervention
* Not uncommon
* Stage 2-0.5-4 hours– heifers longer than cows
Common risk factors include- foetopelvic disproportion, malpresentation, foetal deformities- e.g. schistosoma, akabane
Common risk factors in cattle
* breeding for large birth weight….
* Malpositioning
* Limb/head flexion
* Twin tangles
* Cervical constriction
* Posterior presentation (breech)
Lambing intervention
* Be clean, be gentle, use lots of lube- consider relaxation assistance- epidural, GA, positioning (can easily elevate hindquarters)
* Birth canal is easily traumatized
Intervention of mare parturition
* be aware of history
* Size generally not an issue like in cows
* once rupture of chorioallantois expect steady progress
* be ready to intervene if malpresentation e.g. neck, limb flexion, posterior presentation
* Length of limbs and muzzle make life challenging
* Foal “red bag”
* Failure of cervical star to rupture at cervical pole- thinner region
* true emergency
* need to rupture chorioallantois and deliver foal ASAP
Intervention in stage III mares
* often require intervention
* foetal membranes usually delivered within 30 to 90 minutes after end of stage II
* some people give oxytocin
* retained when not released by 3-6 hours post foaling
Dystocia intervention in mares
* Clean, gentle, use lots of lube, consider relaxation assistance- epidural, GA, positioning
* birth canal is easily traumatized
* foals presented normally may get stuck at shoulders
* be alert for warning signs- maternal/foetal distress, malodour, discolour, stasis, etc.
Lactogenesis vs. Galactopoiesis?
Lactogenesis is the transition from pregnancy to lactation where the mammary gland starts to produce colostrum and/pr milk
* Galactopoiesis is the maintenance of milk production, once it has started
How many litres of blood does it require for 1 L of milk? Where does the blood supply come via? Main vein? Main lymphatic drainage?
500 L
Blood supply comes from the inguinal canal to supply the udder– external pudendal a. is the main supply
* main venous drainage is the superficial cranial epigastric v. or the milk vein.
* main lymphatic drainage: supf. inguinal LNs
Innervation of the udder?
* First and second lumbar nerves
* Perineal nerve
* Genitofemoral (inguinal) nerve- skin over the mid regions of the udder and the sole innervation to the substance of the gland and deeper tissues of the teats
What are some defence mechanisms in the mammary gland?
* sphincter muscles at the teat
* teat canal is lined with keratin to prevent bacterial entry: teat canal keratin is composed of fatty acids that are BACTERICIDAL for S. aureus, S. hyicus, C. bovis, S. agalactiae
* Large cistermn in cows and goats– serves as a form of defence as bacteria will be flushed out
* WBCs migrate
BMCC vss ICCC
Bulk Milk Cell Count- measuring cells in a vat
Individual cow cell count- measuring cells from an individual cow during an individual milking (< 120,000 cells per ml– infected can be millions)
** Suitable for human consumpton, BMCC= 400,000 cells per ml
Mammogenesis
* Proliferation of the mammary duct system begins at puberty though is underdeveloped– udder development occurs mostly by mid-gestation
* Under the control of estrogens, GH, adrenal steroids AND alveoli under the control of progesterone and prolactin
What is the key hormone with lactogenesis?
Prolactin is the key hormone with the secretion of milk, or lactogenesis (Growth hormone too in ruminants)
* Prolactin is released in conjunction with stimulation of the teat through either suckling or the milking process– sensory stimuli cause blockage of dopamine release, and dopamine is a major inhibitor of prolactin secretion
** Prolactin at periods of 12 hour release is sufficient to maintain lactogenesis
How does milk let down occur?
Active contraction of myoepithelial cells surrounding the alveolus for efficient milk ejection
** myoepithelial cells are particularly sensitive to oxytocin- produced in response to massage of teats and other stimuli
If maximal neonatal viability is the goal, what is the induction time period to be following for the cow, ewe (doe), mare, and sow?
What are some indications for induction of parturition?
* sows- allows for cross mothering if needed, labor
* stop “late calving” so cows will be recovered and ready to get pregnant again at the next mating period
* to be able to observe and help in a birth
* terminate prolonged gestation in a cow, not in a mare
* for foals at risk of neonatal isoerythrolysis (NI)
How do you induce a cow?
* short acting corticosteroids (Dexamethasone sodium phosphate)– RFM, calve between 1-6 days, PGF2alpha- RFM, long acting corticosteroids– 2-3 months PRIOR to term in order to get cows back in cycle
** must be at least 6 months pregnant, closely observe as they are likely to nee dhelp
Induction of an ewe? Doe?
Less likely to occur.. short acting corticosteroids
Doe- PGF2alpha, short acting corticosteroids
Induction in a mare?
* Later than 330 days gestational age, relaxed cervix (at least one finger on vaginal exam), have colostrum present in udder** MOST IMPORTANT
*NO INDUCTION IF FEBRILE or foal is thought to be not viable
** Oxytocin– virtually immediate, NO to PGF2alpha (increased foetal deaths!!!)
Induction of sow?
Prior to day 111 not recommended due to increased risk of neonatal death
PGF2alpha, oxytocin
Induction in a bitch/queen?
* Rarely indicated
When is induction of abortion relatively safe?
Early pregnancy, after mid gestation it is associated with increased risk of
* failure of induction of abortion with maintenance of pregnancy to term
* Requirement for multiple treatments
* Difficult delivery with risk of trauma to birth canal
* Post-partum complications such as retained placenta, metritis, and/or delayed involution
Indications for inducing abortion?
* Female mated by a non-desired male, female too young or immature at mating, female entering feedlot, pathology of repro tract or musculo-skeletal system of the dam with the potential to interfere with full term pregnancy, mare with twins, out of season breeding
Induction of abortion in cow?
PGF2alpha +/- corticosteroid, manual crushing of amnion, allantois, and foetus, long acting corticosteroid (more reliable in later gestation)
Induction of abortion in a mare?
* PGF2alpha, cervical dilation and intrauterine infusion of saline & irritants (tetracycline)- not recommended after 7-8 months due to risk of dystocia, manual dilation of cervix and removal of foetus (not recommended after 7-8 months)
Induction of abortion in ewe, doe, and sow?
* PGF2alpha
Induction of abortion in bitch? Queen?
Oestrogens during first 5 days after mating, PGF2alpha in later stages (Aglepristone- synthetic steroid with antiprogesterone activity)
* Queen: estradiol cypionate by Intramuscular injection with 40 hours of mating, PGF2alpha later on
Why do smaller litters encounter more problems in the bitch?
* One or two puppies are not able to initiate parturition and if they do so are generally much larger in size (compared to a larger litter) and therefore are more likely to have foetopelvic malpresentation
During stage 1 in a horse, what ligament relaxes? What ruptures during stage 1?
Sacroiliac ligament and sacroschiatic
** The chorioallantois is forcefully pushed through the cervix and ruptures at the cervical star during stage 1
What is stage 3 in the equid?
* There is normally rapid break down between the chorioallantoic membrane and the endometrium (within 4 hours). The weight of the placenta (usually still hanging from the umbilical cord) acts as a weight. This constant traction and uterine involution help facilitate foetal membrane removal.
What is a common cause of non-obstructive dystocia in a bitch? What interventions are appropriate?
A lack of abdominal straining. This can be induced by either exercising the bitch (walking or gentle running) or initiating Ferguson’s reflex by tickling the dorsal vaginal wall.
** primiparous (first time) or stressed bitch for other reasons may do well when put in a low stress environment with the ower or administration of a low dose sedative (usually a partial opioid)
What are some indicators for potential dystocia in a bitch?
* weak irregular straining for more than 2-4 hours
* strong regular straining for more than 30 minutes with no progression
* foetal fluid passed more than 2-3 hours ago with no progression
* greenish discharge (in queens dark red) but no puppy is born with in 2-4 hours
* 2-4 hours since last puppy was born
* Stage 2 labor for more than 12 hours
* Low foetal heart rate
