Parturition

1
Parturition

• 4-6 weeks prior to due date mares should be where
  they will foal
• Clean and dry
• Protection
• Allows for acclimation
• Exposure to organisms indigenous to the foaling
  area
• Opportunity to develop antibodies

2
Parturition

• Antibodies transferred to foal through the
  colostrum
• Move to area that affords closer more frequent
  observation
• Removal of caslicks

3
Parturition

• The fetus triggers the onset of parturition
• At the end of gestation the fetus approaches the
  space limitations of the uterus and as a result
  the fetus is stressed.
• This stress causes the fetal AP to secrete ACTH
  to stimulate the fetal adrenal cortex to produce
  corticosteroids.

4
Parturition

• Physical changes are
• Vulvar laxity and edema
• Vulvar discharges
• Relaxation of pelvic ligaments
• Udder enlargement
• Udder size and secretion most reliable indicator
• Waxy secretion on teat ends

5
Parturition

• Monitoring milk secretions
• gt60 g of IgG per liter
• Changing electrolyte contents
• Concentrations of minerals
• Ca and Mg Increase 2-4 days prior
• gt10mmol/L of Ca (atomic absroption
  spectrophotometry)
• Kits available

6
Parturition

• Three stages
• Preparatory stage
• 30min-4hours
• Restless signs similar to colic
• Associated with uterine contratctions
• Cervical dilation
• Cranial portion of fetus rotates from a
  dorsopubic through a dorsoilial to dorsal sacral
  position
• Contractions push foals forefeet and muzzle into
  dilating cervix

7
Parturition

• Preparatory stage
• Roll from side to side
• Lie down stand up
• Activity important for fetal repositioning
• Chorioallantois ruputures and allaantoic fluid
  escapes

8
Parturition

• Second stage
• Marked by complete cervical dilation
• Fetus passes into the birth canal
• Oxytocin from posterior pituitary reinforces
  existing uterine contractions
• Assists in fetal expulsion

9
Parturition

• Second stage
• Within 5 min of chorioallantioc rupture the
  amnion presents itself
• White glistening membrane
• Feet first with soles directed downwards followed
  by the nose
• Most forcful contratction occur when head and
  shouders pass through the mares pelvis
• The amnion ruptures at this point

10
Parturition

• Second stage
• Explosive and short-lived
• Delivery of the fetus usually occurs within 20
  -30 min
• If delivery takes longer fetal position and
  posture must be assessed

11
Parturition

• Third stage
• Expulsion of fetal membranes and uterine
  involution
• Plactenta expelled typically 30min to 3hours
  after foaling