Progesterone

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Progesterone, considered colloquially as the pregnancy hormone is an androgen produced by the corpus luteum of bitches[1].

Normally present in low doses in non-pregnant bitches, its level rises during the diestrus phase[2][3].

The production of progesterone by the follicle begins prior to ovulation at the end of proestrus and reaches the levels of about 5 ng/ml in peripheral blood plasma at the time of ovulation[4]. During the formation of the corpus luteum (until day 15 - 20 post ovulation) progesterone rise markedly and start to decrease gradually until approximately day 60 of pregnancy when a steep prepartal progesterone decline is observed in pregnant animals (prepartal luteolysis) as a prerequisite for parturition[5]. This rapid drop in progesterone coincides with an increase in PGF2α levels due to increased cyclooxygenase 2 production in the fetal trophoblast[6] and strongly implies a role of PGF2α in the onset of parturition[7].

In non-pregnant dogs, progesterone levels progressively decrease during the extended luteal regression (up to 1 - 3 months), dropping to < 1 ng/ml at anoestrus[8].

Aglepristone, a synthetic progestagen is used for control of aggression in dogs, to assist maintenance of pregnancy in low-progesterone bitches. caution must be exercised with long-term administration of progesterone due to the greater risk of mammary tumor development[9].

Deslorelin, a synthetic GnRH agonist, reduces levels of estrogen, testosterone and progesterone and is to to induce anestrus and prevent mesalliance.

Abnormal fluctuations of progesterone are associated with a number of conditions including:

References

  1. Kowalewski MP (2012) Endocrine and molecular control of luteal and placental function in dogs: a review. Reprod Domest Anim 47(6):19-24
  2. Willson CJ et al (2012) Effect of estrous cycle phase on clinical pathology values in beagle dogs. Vet Clin Pathol 41(1):71-76
  3. Reynaud K et al (2012) Folliculogenesis, ovulation and endocrine control of oocytes and embryos in the dog. Reprod Domest Anim 47(6):66-69
  4. Concannon PW et al (1989) Biology and endocrinology of ovulation, pregnancy and parturition in the dog. J Reprod Fertil Suppl 39:3–25
  5. Nohr B et al (1993) Investigation of the endocrine control of parturition in the dog by application of an antigestagen. J Reprod Fertil Suppl 47:542–543
  6. Kowalewski MP et al (2010) Canine placenta: a source of prepartal prostaglandins during normal and antiprogestin-induced parturition. Reproduction 139:655–664
  7. Kowalewski MP et al (2011) Luteal and placental function in the bitch: spatio-temporal changes in prolactin receptor (PRLr) expression at dioestrus, pregnancy and normal and induced parturition. Reprod Biol Endocrinol 9:109
  8. Hoffmann B et al (1994) Investigations on hormonal changes around parturition in the dog and the occurrence of pregnancy-specific non conjugated oestrogens. Exp Clin Endocrinol 102:185–189
  9. IARC (1974) Progesterone. In Sex Hormones. IARC Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Humans, vol. 6. Lyon, France: International Agency for Research on Cancer. pp:135-146