The muscular canal that forms from the uterus to the outside of the body through which the fetus passes during birth. Birth canal is formed by the uterus, cervix and vagina within the pelvic bones and their attachments

1. PARTURITION IN DOMESTIC
ANIMALS
Dr. Farooz A. Lone
Assistant Professor, Ph.D ( Gold Medalist)

2. Parturition: Delivery of fetus through the birth canal on completion
of gestation period.
or
Physiological process by which the pregnant uterus delivers the fetus
and placenta from the maternal animal.
The muscular canal that forms from the uterus to the outside of the
body through which the fetus passes during birth.
 Birth canal is formed by the uterus, cervix and vagina within the
pelvic bones and their attachments.

3. Symptoms of approaching parturition
Cow, Ewe, Goat
 Separation from herd
 increased walking/searching
 Increased transition from standing to lying and vice versa
 Licking own body and attention toward abdomen
Scraping or pawing the ground
 Less feeding behaviour
 Relaxed ligaments 24 - 48 h prepartum
raised tail head frequent urination
 restlessness
Bitch
Vomition,
 Drop in 1-2°C rectal temp 24 h prepartum
Nesting behavior.
Mare……………….Sweating, Waxing of teats, Restlessness

4. Symptoms of approaching parturition

5. Stages of parturition
Stages
Stage 1: cervical
dilatation
Stage 3:
Expulsion of
fetus
Stage 2:
Delivery of
the fetus

6. 1st Stage: Cervical dilatation
• Changes not visible externally
• Preparation of birth canal and foetus for expulsion
• Signs of discomfort, mild colic, restlessness with elevated pulse and
respiratory rate, body temperature falls
• Structure of cervix changes
• Onset of myometrial contractions
• Foetus assumes the disposition for expulsion

7. Cervical Changes
• Loosening of the ground substance due to changes in the
composition of collagen components.
• Increased incorporation of water which permits collagen fibres to
separate under extension forces.
• Cervix dilates: external os opening before internal os and becomes
cone shaped due to wide dilation of external os.
• Simultaneous shortening and internal os dilation.
• Vagina and uterus form continuous canal that becomes tightly
engaged by the distended allantochorion

8. Cervical Changes

9. Onset of myometrial contractions
 Cervi-cotubular contractions prevent the premature
displacement of fetuses, thus ensuring orderly expulsion from
the horns
 Isolated ,uncoordinated waves changes to regular and
coordinated peristaltic type.
 Frequency increases from 12-24 per hour in last 2 hours to 48
per hour just before expulsion (30 per hour in ewe).
 Presence of cervico-tubular and tubular-cervical contractions.
 Placental attachment becomes less intimate. Superficial cells
undergo fatty degeneration
.

10. Fetal orientation/disposition
• Separation of margins with haemorrhage in deciduate
placenta.
• Becomes more active and disposes itself.
• Progressive rotation from ventral to dorsal position and fore
limbs, head and neck extended in foal and puppy.
• In calf and lamb extension only.
• Flexed knees of calf first occupy dilating cervix; 30 minutes
later digits are in cervix and it extends carpal joints in its
efforts to ‘stand up in utero’.
.

11. Fetal orientation/disposition
.

12. Duration
.
Animal 1st
Stage (hrs)
Cow, Buffalo 2-6
Mare 1-4
Ewe 2-6
Sow 2-12
Camel 2-7
Bitch 12

13. 2nd. Stage: Delivery of fetus
.
• Refers to expulsion of foetus
• In polytocous species stage cannot be separated from 3rd stage.
Sign:
• Appearance of abdominal contractions, superimposed upon onset of
each myometrial contractions.
• Disappearance of cervico-tubular contractions.
• Ferguson’s reflex
• Allanto-chorionic sac ruptures and gush of urine like fluid escapes
from vulva.
• Amnion traverses vagina and appears at vulva as ‘water-bag’ with
foetal limbs.
• Foetal head next occupies vulva, contractions of uterine and
abdominal muscles reach climax of expulsive effort, maximum
effort coinciding with the birth of the foetal occiput.
• Further straining causes foetal thorax to pass through vulva.
• Usually, birth of hips quickly follows and hind limbs may be
expelled.

14. .
• Foetus is born in amnion and quick movement causes its rupture;
respirations, then begin.
• In mare, cow and ewe (when monotocous) foetus is usually
delivered in anterior presentation, dorsal position and extended
posture.
• In polytocous bitch and sow up to 40–45% of foetuses may be
normally delivered in posterior presentation.
• Duration
Animal 2nd Stage
Cow, Buffalo 70 min
Mare 17 min
Ewe 1 hr
Sow 4 hrs
Camel 30 min
Bitch 6-12 hrs

15. .
3rd. Stage: Expulsion of fetal membranes
• After 2nd stage, regular abdominal contractions largely
• cease. (Gillette and Holm, 1963)
• Myometrial contractions persist; decrease in amplitude.
• These contractions are important for dehiscence and expulsion of
fetal membranes.
• Waves of contractions passing from uterine tube to cervix persist,
but in cow and sow reappearance of contractions in reverse
direction.
• Weakening of acellular layer of adhesive protein, ‘glue line’
between cotyledonary and caruncular epithelium, is probably
important in ensuring placental separation.
• In last 5 days of gestation collagenisation of placentome and
flattening of maternal crypt epithelium in cow.
• Foetal villi shrink, owing mainly to sudden loss of turgidity related
to escape of blood from foetal side of placenta when umbilical cord
ruptures.

16. .
• Early degenerative or maturational changes which are seen in
caruncles of ewe and cow, cause separation of fetal membrane.
• Apex of allanto-chorionic sac becomes inverted and as sac is
‘rolled’ down cornua the fetal villi are drawn out of crypts.
• This forms a mass within maternal pelvis which stimulates reflex
contractions of abdominal muscles leads to expulsion of fetal
membranes.
• Domestic animals normally eat afterbirth except Mare.
• In polytocous species, dehiscence and expulsion of fetal membranes
are interspersed with fetal births.
• Stimulus of suckling causes release of oxytocin, which promotes
‘letdown’ of milk and augmentation of myometrial contractions.
• Suckling resulted in greater synchrony of contractions and increase
in number of tubo-cervical contractions.
• Suckling exerts a favourable influence on expulsion of afterbirth.

17. .
Animal 3rd
Stage
Cow, Buffalo 6-12 hrs
Mare 30min-3hrs
Ewe 2-3 hrs
Sow 4 hrs
Camel 1 hr
Bitch Along with fetus or
shortly

18. .
Cow

19. Theories of parturition initiation
Physical factors
Increase in fetal size: this increases uterine irritability
 Uterine distension : reversal of progesterone block
Fatty degeneration of placenta and presence of infarcts:
leads to interference in fetal nutrition
Biochemical factors:
Increase in CO2 tension in maternal blood due to increased fetal
activity…………………..this ↑uterine contractility
Release of fetal antigens: →serotonin →release of
collagenase and stoppage of blood supply to cotyledons.

20. Neuroendocrine factors: Fetal factors
•↑ in CRH in hypothalamus →stimulate ACTH
•↑ in ACTH by pituitary →stimulate cortisol release
•↑ in cortisol from adrenals→ convert P4 to E2 & release of PG

21. Maternal factors
Reversal of P4 block → ↑ myometrial contractility
Release of relaxin → dilation of the birth canal
Placental estrogen rise →release of PG ↑ myometrial
contractility
Pro-inflammatory cytokines → dilation of the birth canal
Release of PG → softening of cervix, contractions ↑
Release of Oxytocin → ↑ myometrial contractions

22. Stage 1 (Initiation of Parturition)
Stage 1 (Initiation of Parturition)
Fetal Stress
Fetal Stress
Due increase in size and limited space
Fetal
Adrenal Gland
Fetal
Adrenal Gland
Corticoids (cortisol)
Corticoids (cortisol)
Corticoids (cortisol)
Corticoids (cortisol)
Release of pituitary ACTH
(adreno-corticotropic hormone)
Release of pituitary ACTH
(adreno-corticotropic hormone)
1) Removal of progesterone block
2) Elevation of repro. tract secretion
1) Removal of progesterone block
2) Elevation of repro. tract secretion

23. Removal of Progesterone Block
Removal of Progesterone Block
How does progesterone secretion is inhibited?
Elevated cortisol promotes the synthesis of 3 enzymes
These 3 enzymes convert progesterone to estradiol
Elevated cortisol promotes the synthesis of 3 enzymes
These 3 enzymes convert progesterone to estradiol
17 hydoxylase
17 hydoxylase 17-20 lyase
17-20 lyase Aromatase
Aromatase

24. Pregnenolone (C21)
Estrogen (C18)
Progesterone (C21)
Testosterone (C19)

25. Fetal hypothalamus
↓
Fetal Pituitary
↓
ACTH
↓
Fetal adrenal
↓
Adrenal corticosteroids
↓
Convert progesterone to estrogen ← Feto-placental estrogens → Relaxin
↓
↓ → →→ → →→→ → →→↓ Cervical softening ← ← ← ←
↓
Cotyledons / Myometrium ↑
Proinflamatory cytokines
↓
Luteolysis ← Release of PGF →oxytocin ↓
↓ ↓
↓
Decrease in serum progesterone ↓
↓→ ↓ ↑ Abdominal contractions
Myometrial contractions → Fetal Expulsion
↑
Oxytocin
↑
Posterior Pituitary
Possible endocrine changes that occur during the peri-parturient
period in the sow, ewe, cow and their effects

27. Parturition
Fetal Nutritional
Demands
Placental
Insufficiency
Hypothalamus Anterior
Pituitary
Adrenal
Cortex
CRH ACTH
Fetal Corticosteroids
(Cortisol)
Lung
(surfactant)
Liver
(glycogen)
Thyroid
(metabolism)
Progesterone Estrogen PGF2a
Uterine
Contractions
PGF2a
Relaxin
Oxytocin
Uterine Endometrium
» Oxytocin receptors
Ovary
(CL)
Cow, Sow
Triggers
CL
Regression
Placentome
Cervical
Ripening

28. Final Role of Oxytocin
Ferguson’s reflex
Sensory Neurons in Cervix
Oxytocin from
Posterior Pituitary
Myometrial
Contractions

29. Orientation of Fetus
•Fetus must reorient prior to parturition
•It occurs during first stage of parturition
•Initially on back
•Reorient so that feet and head will exit first
•Breech ………..Rear of fetus comes first
• Orientation not important in pig
•Abnormal orientation results in dystocia

30. Fetal Orientation

31. Fetal Orientation

32. Prepartum fetal changes:
•Changes do occur in the fetus before delivery and these are essential
because the fetus has to prepare itself for the external environment
outside the uterus. The changes include
•Maturation of fetal lungs: The surfactants in the lungs increase
which reduce the surface tension within the alveoli.
•Increased output of tri-iodothyronine and catecholamines to
meet the increased metabolic demands.
•Closure of the ductus arteriosus and the closure of the foramen
ovale.
•Increased glycogen reserves in the liver to meet the demands
•on delivery by the production of glucose as a source of energy post
delivery.

33. Sequence of parturition events in the cow

34. Parturition in the buffalo

35. 1
2
2
2
3

36. Stages of labor in a goat
1
2
3
• The first water bag(allantochorion) is protruded
• The second water bag (amnion) and the fetus are protruding
through the vulvar lips
• The placenta is being dropped in the third stage of labor