Pseudopregnancy

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Also known as: False Pregnancy — Pseudocyesis — Nervous Lactation

Introduction

The clinical condition of overt pseudopregnancy is usually simply called pseudopregnancy, however a physiological pseudopregnancy occurs in every non-pregnancy ovarian cycle in bitches.

Because the normal luteal phase of progesterone secretion is so long during the canine oestrus cycle, compared to other species, it has been compared to the abnormally prolonged luteal phases observed in pseudopregnant laboratory rodents.

In fact, there is considerable mammary development associated with the luteal phase of every ovarian cycle in dogs but the extent of normal mammary development during metoestrus (dioestrus) varies within and among bitches. It has been suggested that the clinical condition of overt pseudopregnancy actually represents the extreme of the physiological changes that normally occur during dioestrus (metoestrus). There is a fall in progesterone and an increase in prolactin which leads to the clinical signs.

When the changes result in extreme behavior or atypical mammary activity, or are presented as clinical problems involving changes similar to those seen in late pregnancy or the early post-partum period, the condition can best be termed "clinical pseudopregnancy" or "overt pseudopregnancy".

This condition is not uncommon in dogs. It seems likely that it represents the retention in domestic dogs of a previously functional evolutionary adaptation developed when non-bred female wolves of a primitive canine species nursed the litters of other females.

The exact incidence of clinical pseudopregnancy in most breeds is unknown, although it has been estimated to be as high as 50 - 75% in certain breeds.

The incidence of clinical pseudopregnancy may be influenced by age, breed, parity and environmental factors. It has also been suggested that nutritional practices may also have an influence on the occurrence of pseudopregnancy.

Clinical Signs

The condition usually begins with behavioural symptoms such as: restlessness, anorexia, nesting, aggression and mothering inanimate objects.

Physical signs can appear, such as: weight gain, mammary enlargement, milk secretion and let-down.

Complications can occur such as mastitis and mammary dermatitis, but these are not common.

Signs usually disappear after 2-4 weeks, but there is a recurrence of signs at each successive oestrus.

Diagnosis

History and clinical signs should be sufficient to diagnose pseudopregnancy in most cases.

True pregnancy or pyometra should be ruled out by palpation, radiography or ultrasound.

Mastitis will be apparent on clinical exam and will appear as inflamed, swollen and painful mammary glands.

Treatment

Mild cases often need no treatment other that discouraging maternal behaviour. A diuretic such as furosemide can be used to reduce fluid retention and stop lactation. If behavioural signs are present, mild sedation with non-phenothiazine drugs can be an option. Phenothiazine drugs should not be used as they encourage prolactin release.

If the condition is self-limiting, signs will usually disappear within 1-3 weeks.

The preferred medical method of ending pseudopregnancy is the use of prolactin-supressing drugs such as the dopamine agonists cabergoline and bromocriptine. Milberone can also be given.

Progesterone, oestrogen or testosterone treatment is not recommended.

Ovariohysterectomy should be considered in all bitches not to be used for breeding. It should preferably be done during anoestrus, as spaying during lactation can result in a prolongation of pseudopregnancy.

The prognosis is good, although recurrence is common in subsequent oestrous cycles.

There is no decrease in fertility following an episode of pseudopregnancy.


Pseudopregnancy Learning Resources
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Small Animal Abdominal and Metabolic Disorders Q&A 16


References

Pasquini, C. (1999) Tschauner's Guide to Small Animal Clinics Sudz Publishing

Gobello, C. (2001) Canine Pseudopregnancy: A Review In: Recent Advances in Small Animal Reproduction IVIS Publication




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