ISSN 2398-2950      



Synonym(s): Pseudocyesis, false pregnancy, phantom pregnancy.


  • Hormonally mediated in the non-pregnant queen due to elevated progesterone after ovulation.
  • Results in prolonged luteal phase with the absence of pregnancy.
  • Cause: spontaneous (rare), sham copulation, sterile mating.
  • Signs: inter-estrus interval prolonged to 45 days or more.



  • Hormonal changes associated with non-pregnant luteal phase.
  • Progesterone concentrations Progesterone assay similar to first few weeks of pregnancy (but duration of luteal phase is shorter, ie 45 vs 65 days).


  • Hormonal changes of metestrus and pregnancy are initially similar.
  • Increasing serum progesterone Progesterone assay and possibly increased prolactin.
  • Queens are induced ovulators.
  • Sham copulation, sterile mating or spontaneous (rare)   →   ovulation   →   corpora lutea develop and secrete progesterone.
  • Luteal domination   →   endometrial hyperplastic changes similar to pregnant uterus.
  • Progesterone levels decline by 5-9 weeks   →   prolactin release   →   mammary development.


  • Non-pregnant luteal phase: 45 days.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Gudermuth D F, Newton L, Daels P et al (1997) Incidence of spontaneous ovulation in young, group-housed cats based on serum and fecal concentrations of progesterone. J Reprod Fertil Suppl 51, 177-184 PubMed.
  • Brown J L, Wasser S K, Wildt D E et al (1994) Comparative aspects of steroid hormone metabolism and ovarian activity in felids, measured noninvasively in feces. Biol Reprod 51 (4), 776-786 PubMed.
  • Tsutsui T & Stabenfeldt G H (1993) Biology of ovarian cycles, pregnancy and pseudopregnancy in the domestic cat. J Reprod Fertil Suppl 47, 29-35 PubMed.
  • Boomsma R A, Mavrogianis P A, Verhage H G (1991) Changes in endometrial and placental protein synthesis and morphology during pregnancy and pseudopregnancy in the cat. Biol Reprod 44 (2), 345-356 PubMed.
  • Jöchle W, Arbeiter K, Post K et al (1989) Effects on pseudopregnancy, pregnancy and interestrous intervals of pharmacological suppression of prolactin secretion in female dogs and cats. J Reprod Fertil Suppl 39, 199-207 PubMed.
  • Wheeler A G, Walker M, Lean J (1987) Influence of adrenergic receptors on ovarian progesterone secretion in the pseudopregnant cat and estradiol secretion in the oestrous cat. J Reprod Fertil 79 (1), 195-205 PubMed.
  • Banks D R, Paape S R, Stabenfeldt G H (1983) Prolactin in the cat. I. Pseudopregnancy, pregnancy and lactation. Biol Reprod 28 (4), 923-932 PubMed.
  • Shille V M & Stabenfeldt G H (1979) Luteal function in the domestic cat during pseudopregnancy and after treatment with prostaglandin F2 alpha. Biol Reprod 21 (5), 1217-1223 PubMed.

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