Puerperium - Sow

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Also see General Puerperium

Changes of the puerperium must occur rapidly, with a return to the normal pregravid state, so that pregnancy can occur as quickly as possible after weaning.


  • Rapid initial uterine shrinkage in the first 5 days postpartum.
  • After day 6, most uterine weight loss is due to changes in the myometrium:
    • Reduction in cell size
    • Reduction in cell numbers
    • Reduction in the amount of connective tissue
  • Uniform decrease in thickness of the endometrium and myometrium.
  • Complete by 28 days
  • In early-weaned sows, uterine involution is slower.
  • The morphology and physiology of the genital tract may not be optimal for fertilization and blastocyst implantation in sows weaned at farrowing or shortly after, resulting in a reduced rate of gestation or a reduced litter size.

Restoration of the Endometrium

  • 1 day after farrowing, the uterine epithelium is low columnar or cuboidal.
    • Extensive folding present during pregnancy
  • At 7 days, epithelial cells are very low and flattened, showing signs of degenerative change.
    • Also signs of cell division, responsible for regeneration of the epithelium.
  • Complete and capable of sustaining another pregnancy after 21 days.

Return to Ovarian Cyclicity

  • Suckling and weaning have an effect on return to ovarian cyclicty (ovarian rebound) and other puerperial changes in the tract.
  • Mostly no return to oestrus and no ovulation until piglets are removed.
  • Time to first ovulation can be shortened by temporary removal of the whole litter for varying periods during the day (partial weaning), or permanent removal of part of the litter.
  • Rapid regression of corpora lutea of pregnancy, with cellular degeneration occuring by 3 days postpartum.
  • By day 7 postpartum, corpora lutea are mainly connective tissue.
  • Follicular activity occurs during suckling, which is sometimes associated with behavioural oestrus shortly after farrowing.
    • No ovulation, follicles become atretic
  • Preovulatory surge of LH within 7 days of weaning.
  • Prolactin concentrations are high during lactation but decline rapidly to basal levels within hours after weaning.
  • Follicular growth and ovulation are supressed during lactation due to supressed LH secretion.
  • FSH concentrations rise after weaning.