What are the clinical signs of chronic pseudopregnancy?

The clinical signs are similar to normal pseudopregnancy although behavioural changes, in particular aggression, are more common than mammary development and milk production⁴.

Why does it occur?

Pseudopregnancy occurs during the metoestrus (progesteronea steroid hormone secreted by the corpus luteum of the ovary that maintains pregnancy and promotes the development of the mammary glands. dominant) phase and is associated with the production of the hormone prolactina hormone released from the anterior lobe of the pituitary gland that stimulates the secretion of progesterone by the corpus luteum and initiates and maintains lactation...  Spaying during this period results in a rapid drop in progesteronea steroid hormone secreted by the corpus luteum of the ovary that maintains pregnancy and promotes the development of the mammary glands..  Progesteronea steroid hormone secreted by the corpus luteum of the ovary that maintains pregnancy and promotes the development of the mammary glands. inhibits prolactina hormone released from the anterior lobe of the pituitary gland that stimulates the secretion of progesterone by the corpus luteum and initiates and maintains lactation. production and therefore the drop in progesteronea steroid hormone secreted by the corpus luteum of the ovary that maintains pregnancy and promotes the development of the mammary glands. results in an increase in prolactina hormone released from the anterior lobe of the pituitary gland that stimulates the secretion of progesterone by the corpus luteum and initiates and maintains lactation., which is the hormone responsible for the clinical signs of pseudopregnancy¹.

Why does it not resolve by itself?

The processes that result in normal spontaneous recovery following pseudopregnancy is unknown⁴.  However it appears that spaying somehow stops this mechanism from working.

Is treatment using Galastop® effective in these cases?

A study published in the Veterinary Record recorded an 86% success rate when treated orally with Galastop® (carbergoline) at 0.1ml/kg for 5 days⁴. However, prolonged treatments of up to 3 weeks may be required in some cases³ and prevention is better than a cure.

When should a bitch be spayed following a season to reduce the risk of chronic false pregnancy developing?

It is important never to spay a bitch that is suffering from clinical pseudopregnancy^1,2,3,4.  However, as mentioned before, some pseudopregnancy cases can be silent and difficult to detect. There is a low risk of inducing chronic pseudopregnancy if a bitch is spayed within 5 weeks after the end of oestrous³.  However, it is generally recommended to wait until the bitch is in anoestrous i.e. from 3 months after the end of oestrous.  By this time, the ovaries (corpora lutea) have become inactive and the blood supply is minimal².  However, silent pseudopregnancy can still occur at 3 months after the end of oestrous¹. Some authors therefore recommend spaying further into anoestrous, i.e. at 4 months after the end of oestrous^1,4.

When should a bitch be spayed following having puppies?

After parturitiongive birth, a bitch can be spayed as soon as the puppies are completely weaned (6-8 weeks) and lactation has finished².

What should I do if an owner wants to spay a bitch suffering from pseudopregnancy?

It is advisable to treat the pseudopregnancy with Galastop® (carbegolone) at a dose of 0.1ml/kg per day.  Usually a 4-6 day course is sufficient to resolve the clinical signs.  After the clinical signs have resolved, it is advisable to wait 7 days before spaying to allow 3-4 days for the cabergoline to leave the system plus a few more days to ensure that the pseudopregnancy doesn`t return.

References

¹ = Harvey M, BSAVA Manual of Small Animal Reproduction and Neonatology, Chapter 4, p41, published by BSAVA, Shurdington
² = England G.C.W, Allen`s Fertility and Obstetrics in the Dog, p209-210, Blackwell Science
³ = England G.C.W., Technical Review On the Use of Antiprolactinic Treatments (available on request)
⁴ = Harvey M.J.A, Dale M.J, Lindley S, Waterston M.M (1999), A Study of the aetiology of pseudopregnancy in the bitch and the effect of cabergoline therapy, The Veterinary Record, April 17th, p433 - 436