Parturition in Animals

Parturition

• The act of giving birth in animals.
• Familiarity with normal parturition is essential.
• Ability to differentiate between physiological and pathological births is necessary.
• Appropriate and timely intervention increases the chances of survival for both mother and offspring.

Initiation of Parturition

• Uterine musculature is key during labour.
• Essential physiological changes mark the transition from gestation to birth.
• Biochemical ripening of the cervix occurs.
• The myometrium's contractile potential is released.
• Humoral, biochemical, neural, and mechanical factors are involved in these transformations.

Parturition in Ewes

• Parturition is triggered by the activation of the fetal hypothalamus-pituitary-adrenal (HPA) axis.
• The paraventricular nuclei are the areas of the hypothalamus involved.
• The fetal HPA axis resembles the adult one, but the fetal brain is still developing during late gestation.
• The fetal brain communicates via the placenta.

Fetal Hypothalamus Activation Theories

• Maturation of the fetal hypothalamus leads to critical synapse development in the paraventricular nucleus that increases neuroendocrine function.
• The hypothalamus gains the ability to respond to placental hormones.
• Fetal stressors like hypoxia, hypercapnia, and changes in blood pressure and glucose play a role.

Progesterone Sources During Pregnancy

• In cows, the corpus luteum (CL) is the primary source of progesterone during bovine pregnancy.
• The placenta produces progesterone between 150 and 200 days of gestation.

Role of CL in Does (Nanny Goats)

• CL provides the necessary progesterone for gestation.
• Fetal plasma ACTH and prepartal increase in fetal cortisol have a positive association.
• Progesterone synthesis by the CLs is diverted into estrogen.
• Changes in the estrogen to progesterone ratio stimulates synthesis of PGF2a in the ewe, which results in luteolysis and further decline in progesterone.
• Progesterone disappears from the circulation before parturition.

Hormonal Changes in Sows

• Progesterone from the CLs needed to maintain pregnancy throughout its duration.
• Parturition is preceded by an increase in fetal plasma cortisol levels.
• Increased fetal cortisol leads to increased maternal blood oestradiol and PGF2a metabolites coupled with decreased progesterone.

Hormonal Changes in Bitches and Queens

• Prolactin levels increase as progesterone decreases 1 to 2 days before whelping.

Relaxin

• Relaxin is a polypeptide hormone that belongs to the insulin superfamily.
• It is responsible for relaxing the pubic symphysis in guinea pigs.
• The most potent relaxin sources are CLs in pregnant sows.
• Relaxin is produced by other tissues; in pigs, it is produced by preovulatory follicles.
• In horses, dogs, and cats, the sole source is the placenta.
• In horses, it's produced by the noninvasive trophoblast of the early equine embryo.

Actions of Relaxin

• Has a wide range of effects on target tissues, including: -Pubic symphysis -Pelvic ligaments -Servix -Myometrium -Mammary gland

Relaxin Effects in Sows

• Stimulates the growth of the vagina, cervix, uterus, and mammary glands during late pregnancy.
• Causes softening of the cervix before parturition.
• Generally reduces both the frequency and amplitude of uterine contractions.
• Seems to act with progesterone, oestrogens, oxytocin, and prostaglandins.

Fetal Maturation

• Characterized by endocrine changes in late pregnancy.
• These changes that initiate parturition and stimulate maturational changes enable the animal to survive.

Examples of Fetal Changes

• Closure of the ductus arteriosus and foramen ovale.
• Functional development that includes: -Production of surfactant -Glucose homeostasis development -Changes in hemoglobin.
• Fetal cortisol surge links parturition and maturation.

Fetal Preparation for Extrauterine Life

• During intrauterine life, the fetus is in a thermally neutral environment, and at birth it needs to maintain its own body temperature.
• Mechanisms enabling this include: -Accumulation of brown fat and glycogen in late gestation. -Maturation of the thyroid gland.
• Thyroid gland maturation results from prepartum cortisol rise, which stimulates monodeiodination of thyroid hormones and enhances biological activity.

Fetal Adrenal Medulla

• Shows maturational changes that increases the ability to produce catecholamines, especially adrenaline, in response to asphyxia and hypoglycemia.
• Adrenaline, together with fetal ACTH and cortisol, stimulates lung maturation, promoting resorption of fetal fluids within the lungs, enabling normal respiratory function upon birth.

Indications for Preterm Foaling in Mares

• Ensures the presence of skilled assistance, so dystocia can be addressed quickly.
• This increases the survival of the foal.
• It reduces danger to the mare.
• In illness or disease of the mare, preterm foaling can be advantageous.

Preparation and Hormone Preparations for Preterm Foaling in Mares

• The degree of sacrosciatic ligaments and cervix relaxation are examined.
• Used to measure the mammary secretions' ionic composition as signs for readiness.
• Hormone preparations used: -High doses of oxytocin with or without priming with stilboestrol dipropionate.
• When the cervix shows ripening, evidenced by its softness and allowing insertion of one or two fingers into the external os, and with the foal in a normal position, oxytocin can be administered.
• Oxytocin is given at 120 IU to mares weighing between 360-600 kg, and foaling occurs 15 to 60 minutes later.

Induction of Foaling in Ponies

• Dexamethasone, a synthetic corticosteroid, is used.
• PGF2a and its analogue fluprostenol can be used which are single dose. -Can cause serious discomfort which can result in dystocia.
• Fluprostenol induces foaling between 322 and 367 days of gestation, given as a single dose of 250ug to ponies.

Indications for Preterm Calving in Cows

• To advance calving to coincide with suitable pasture for milk production.
• To ensure cows calve at a predetermined time for skilled assistance and prompt attention.
• To reduce birth weight by shortening gestation.
• When diseased or injured, pregnancy can be terminated .

Drugs Used to Induce Calving in Cows

• Corticosteroids: -Long acting -Medium acting -Short acting
• Corticosteroids are immunosuppressive and should be given with broad-spectrum antibiotics if infection is present.
• PGE1, PGE2, and PGF2a.
• Combination of corticosteroids and prostaglandins.

Disadvantages of Preterm Calving

• It is not always effective.
• Calf birth weight is lower.
• There is a higher incidence of retained fetal membranes.
• Milk yield is initially affected with a delay in reaching peak lactation.
• Fertility is fairly normal.
• There can be a reduction in quantity and quality of colostral immunoglobulin.

Stillbirths in Sows

• 75% of stillbirths occur during parturition.
• Stillbirth rate can be affected by the time interval between the birth of the first and last piglets, with prolonged farrowing times resulting in an increase.
• 80% of stillbirths occur during farrowing during the last third of the litter.
• Time interval between the births of two piglets is shorter than the time interval preceding the birth of a stillborn piglet.
• Piglet death may be due to delayed expulsion and this results in the slow expulsion of dead piglets.
• Premature rupture of the umbilicus can be a cause of stillbirths.
• Intensive care and attention during farrowing reduces the stillbirth rate.

Management to Time of Farrowing

• Planning and regulating the timing of farrowing can offer advantages: -Group farrowing facilitates multiple suckling and cross-fostering. -Groups of sows and litters are managed using an "all in, all out" principle for efficient disinfection and cleaning. -Group farrowing facilitates group weaning. -Farrowing can be scheduled during certain days and normal working hours. -Improved reproductive efficiency by shortening the farrowing interval.

Drugs Used in Sows

• Corticosteroids
• Prostaglandins -Dinoprost -Cloprostenol combined with oestradiol benzoate

Parturition in Sows

• Oxytocin is used to the treat sows suffering from uterine inertia shown by prolonged farrowing times
• Delaying has been accomplished in sheep, goats, and pigs (but not in mares) by the pharamacological inhibition of prostoglandin synthesis -Stimulates the B receptors of uterine muscle cells -Clenbuterenol is used succesfully in cows, sows, and ewes

Course of Parturition Physiology

• Essential components of birth and needed for normal births are: -Expulsive forces -Fetus together with its associated fetal membranes and fluids -Soft and bony parts of the birth canal
• Normal birh is when adequate forces expel a normal, corectly disposed fetus, with correct dispositition and fetal membranes, through a dialated cervix and an adequate sized birth canal

Expulsive Forces

• Consist of the contraction of the myometrium.
• Consist of the abdominal musculature
• The fetus will flex its limbs and neck and assume a disposition so its dorsum is adjacent to the greatest curvature of the uterus.
• Body conformation that is streamlined to match the birth canal, to correctly dispose of the fetus.

Maternal Changes for Passage of the Fetus

• To allow passages birth canal must allow
• Changes need must occur in maternal structures: -Cervix must dilate -Bony pelvis and ligaments mus relax -Vagina, vulva, and perineum must soften

Myometrial Contractions

• Myometrium contains myosin and actin. -Contractions initiate when the ATPase of myosin light chain (MLC) is phosphorylated by MLC kinase (MLCK). -Calcium-binding protein calmodulin activates the enzyme
• 2.Myometrial relaxation dephosphorylates the MLC by: -MLC phosphatase -cAMP-dependent protein kinase inhibiting MLCK

Bicornuate Uterus

• Myometrium comprised of 2 layers. -Outer Bundles are arranged parallel to the long axis of the uterus. The contractions cause the uterus to shorten cephalocaudally. It is continuous with cervix, secured with the pelvic activity. Contraction leads to shortening. Uterine horns would be pulled caudally, with the longitudinal bundles contracts Full term fetus in uterus, there is reduced ability the uterus to shorten Contractions can cause dilatation.

Inner Layer of Myometrium

• Myometrium – Fomed by bundle, fibres, and concentrically
• Arranged longitudinal axis, these restrictions restrict the uterine lumen

Effects of Progesterone and Oestrogens on Myometrial Activity

• Progesterone dominance ensures quiescent maintenance.
• Oestrogens has a reversed effect to effect. -Increasing contact -Increasing agonist receptors -Increasing number gap junctions

Progesterone on Myometrium/Contrastile Unit

• Progesterone has opposite effects: -Reduces gap junctions -Agonist receptos -Synthesis of prostaglandin and release of oxycotin -Increases calcium bining

Prostaglandins

• Critical role in parturition
• Initiation of the process of parturition
• control of myometrial contractions
• PGF2a and PGE2 stimulate uterine contractions.
• Oxytocin is responsible patten release
• Cows, sheep, and goat rapid increase.

Oxytocin

• Mare's first increase 18 to 72hrs before delivery
• Pig increase before start of the expulsive tage
• Dogs, pulse increase for birth
• Species, oxytocin in contraction.
• Sensory receptors cause harmone to release.

Hormone Influence on Oxytocin

• Two ways to stimulate uteran contractions: -Increase prostaglandin release -Increased calcium release for MLCK

Stages of Labour

• Four Physiological phase -Phase O, 95% duration to gestation, the myometnum is more qurescent. -Phase 1, Activation phase. -Softening of Cervox -Myometrium to be repaired for contraction

Stage Phase Stimulation

• Phase two involves 1st and 2nd stage of labor.
• Increase mimetal, contractility, dialation of cervix exoulsian of fitis
• Phase 3, after birth stage, found in one or more.

Stages of Labor/Birth

• Stages do ot start abruptu
• First state, prepares for the Canal to remove
• Fetus assumes dispisition for explulsion.

Changes in Cervix in Structure

• Change in ground substance Water incorporation promotes fibre separation
• Sows take 1 hr & 2 days for dililation

Changes in Birth

• Elevated Puse Rate
• Fall In Temperature
• Contractions, uterine musculature, fetus affect, as intimate.

Factors Influencing

• Placental attach remain affect.
• Circulation resistance in marternal side. Aid division of blood mammary.

Other Factors in Parturient Animals

• Fetus, and disposision canal change, head ect extended
• Parturition posture changed.
• Referrence for functions.

Second Stage of Labour

• Expulsion.
• Fells membrane is avoid.
• Abdominal contractions the release.
• Contractions affect plasma oxylocin

Influence

• Allanto chorionic sav rupture
• Amninon and fetus affect
• Muscle Stravaginal

Events During Birth:

• Additional straung in water bag.
• Ruptured fetus
• Amnion, thorax

After Mother Gives Birth

• After is often umbilical and mintues elapse.
• This important burt and can't occur.
• Rupture point occurs at umbillios,
• Labor completes after dellvered

Third Stage of Labor

• After birth, regular, myoneteria, continue.
• Important, ofter species continue.
• Species sucken.
• Suckling promate to meteria.

Care of Parturient Animals

• Put in convinient, paddock.
• Put on test, put in foaling box to serve.
• Mares, need continulos observation
• Maes, majority between 6, and 12, byday, foals have suckled:

Animals and stages

• Cows heifers, moveded maternity to dedicated
• moved, date impenndng calving

Animal Pregnancy

• Sows Farrow 60 - 75% usually
• Membranes a adjacent
• Quiet pregrancy
• Material develop.

Facts on newborn

• PIg reach treats in with 30 mts,
• Mantenes of porline

Other Notes

• Plavental, 4x likely affect
• PIgs affect and worse value
• Bitch, animal, bad, bicheming,
• Lactatin

Bitch

• Prepartation, and restless
• Lactation in primigravidae.
• Tranisent body temperature. Food intial.
• Position change also.