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Pseudopregnancy (phantom pregnancy; false pregnancy; pseudocyesis) is a relatively common phenomenon in small dogs characterized by pregnancy behaviour, physical changes associated with pregnancy, but the absence of foetuses.

Pseudo pregnancy is a normal physiological process that occurs in female dogs, not usually associated with reproductive organ disorders. It is seen 45 - 60 days after a normal estrous (heat) period, as progesterone levels, which rise after ovulation, begin to fall[1]. Decreasing progesterone leads to an increase of prolactin, responsible for most of the behaviors seen during a pseudopregnancy episode[2].

Histologically, during late metoestrous, endometrial epithelial surface cells frequently accumulate fat and thereby adopt a foamy morphology, giving the endometrial lining a characteristic foamy appearance during pseudopregnancy[3].

Clinical signs include mothering of toys, nesting, or even aggression. Mammary development and milk production are common.

Mastitis and vaginal hyperplasia are sometimes observed as a complication. Pseudopregnancy can also be acutely induced by spaying a dog near the end of estrus.

Diagnosis is based on the presence of typical clinical signs in metaoestrous non-pregnant bitches[4].

Treatment usually involves hysterectomy or allowing time for symptoms to abate by normal hormonal resolution.

Proligestone, bromocriptine[5] or cabergoline may be indicated if excessive prolactin production is evident (>4 ng/mL)[6].


  1. Gobello C et al (2001) Study of the change of prolactin and progesterone during dopaminergic agonist treatments in pseudopregnant bitches. Anim Reprod Sci 66(3-4):257-267
  2. Gobello C et al (2001) Dioestrous ovariectomy: a model to study the role of progesterone in the onset of canine pseudopregnancy. J Reprod Fertil Suppl 57:55-60
  3. Bartel C et al (2013) Characterization of Foamy Epithelial Surface Cells in the Canine Endometrium. Anat Histol Embryol Apr 26
  4. Gobello C et al (2001) A review of canine pseudocyesis. Reprod Domest Anim 36(6):283-288
  5. Grünau B et al (1996) The treatment of pseudopregnancy in the bitch with prolactin inhibitors metergoline and bromocriptine. Tierarztl Prax 24(2):149-155
  6. Tsutsui T et al (2007) Plasma progesterone and prolactin concentrations in overtly pseudopregnant bitches: a clinical study. Theriogenology 67(5):1032-1038