A Review of Canine Pseudocyesis

Abstract

The purpose of this article is to review the most relevant features of the physiology, clinical signs, diagnosis, treatment and prevention of canine pseudocyesis (PSC). This is a physiological syndrome, characterized by clinical signs such as: nesting, weight gain, mammary enlargement, lactation and maternal behaviour, which appears in non-pregnant bitches at the end of metaoestrus. PSC is a frequent finding in domestic dogs. Although it is generally admitted that prolactin (PRL) plays a central role in the appearance of PSC, its precise aetiophysiology is not completely understood yet. A number of clinical studies suggest that at some point of metaoestrus circulating PRL levels rise in overtly pseudopregnant bitches. Individual differences in sensitivity to PRL as well as the existence of molecular variants of canine PRL with different bioactivity versus immunoreactivity ratios may help clarify the aetiopathology of PSC. Diagnosis of PSC is based on the presence of typical clinical signs in metaoestrous non-pregnant bitches. Considering that PSC is a self limiting physiological state, mild cases usually need no treatment. Discouraging maternal behaviour and sometimes fitting Elizabethan collars to prevent licking of the mammary glands may suffice in these cases. Sex steroids (oestrogens, progestins and androgens) have been traditionally used to treat PSC but the side-effects usually outweigh the benefits of these medications. Inhibition of PRL release by ergot derivatives [bromocriptine (10-100 microg/kg per day for 10-14 days], cabergoline (5 microg/kg per day during 5-10 days), metergoline (0.2 mg/kg per day during 8-10 days) has proved to be effective for the treatment of canine PSC. Although some of these ergot derivatives present some untoward side-effects, they are transient and can usually be managed. Predisposed bitches not intended for breeding should be spayed as ovariectomy is the only permanent preventive measure.

Hyperprolactinemia and Delusion of Pregnancy

“…It may serve an evolutionary purpose in some species whereby non-reproducing females can feed the offspring of their relatives, if needed [19] . Prolactin has been suggested as playing a central role in the genesis of the common problem of pseudocyesis in domestic female dogs [21] .…”

Heterogeneity of circulating prolactin in the bitch

“…A second point of interest was to compare the molecular profiles of serum PRL between covert and overt pseudopregnant bitches. Since the circulating concentration levels of both PRL and progesterone (P 4 ) have been implicated in the etiology of pseudopregnancy [5][6][7][8], the serum concentrations of these hormones were compared between these two groups.…”

A Case of Pseudo-Pregnancy in Captive Brown Howler Monkeys (Alouatta guariba)

“…This was confirmed by a variety of clinical tests including X-raying of the female's abdomen [Gobello et al, 2001]. The veterinarians also confirmed that the female appeared to be clinically healthy.…”

“…Hormonally, it is caused by the superproduction of progesterone and the abnormal persistence of the corpus luteum [Gobello et al, 2001]. Spontaneous cases of pseudo-pregnancy are widely reported in a number of mammalian species, including dogs, cats, bears, rodents and humans [Drife, 1985;Gobello et al, 2001;Cameron et al, 2003;Schulz et al, 2003].…”