Definition

• Physical and behavioral changes resulting from normal hormonal changes during diestrus and early anestrus in the non-pregnant bitch. The term false pregnancy is a misnomer, since the pattern of hormonal changes is normal.
• Physical, hormonal, and behavioral changes following a non-fertile mating or spontaneous ovulation in the queen.

Pathophysiology

• Hormone profile of pregnant and non-pregnant bitch very similar following ovulation.
• All cycling bitches undergo a lengthy (2+ months) diestrus following ovulation.
• Mammary development and behavioral changes occur under the influence of progesterone and prolactin in late diestrus.
• Galactorrhea (excessive production and inappropriate excretion of milk) is seen following a rise in serum prolactin at the end of diestrus; with severe hypothyroidism-due to resulting hyperprolactinemia.
• False pregnancies in the bitch are thought to occur as a holdover from a period in evolution when females of a pack would cycle at the same time but only dominant individuals would become pregnant. Non-pregnant pack members were available to nurse puppies of the more dominant females.
• Any event that results in an abrupt drop in serum progesterone and rise in prolactin can lead to a clinically overt false pregnancy. Signs are frequently created iatrogenically when ovariectomy or ovariohysterectomy is performed during mid to late diestrus.
• Queens that ovulate spontaneously or ovulate following mating but do not become pregnant experience a 6-7-week period of diestrus due to elevated progesterone concentrations; some queens develop a clinically overt false pregnancy during this time.

Systems Affected

• Reproductive
• Behavioral
• Endocrine

Genetics

N/A

Incidence/Prevalence

• False pregnancies occur in 100% of bitches following ovulation.
• >60% of cycling bitches exhibit signs of false pregnancy.
• Spontaneous ovulation occurs frequently in the queen (35–85%) depending on presence of other queens and tom. False pregnancy occurs after every non-pregnant ovulation in the queen; overt symptoms are uncommon.

Signalment

Signs

Causes

• Decline in serum progesterone concentration and rise in serum prolactin concentration.
• Decline in serum progesterone concentrations due to OVE or OHE during diestrus.
• Hyperprolactinemia-can be due to severe hypothyroidism.

Risk Factors

• OHE or OVE during diestrus
• Does not impact future fertility

Differential Diagnosis

• Pregnancy
• Mastitis
• Mammary neoplasia.
• Mammary hyperplasia (queens)
• Pyometra
• Other causes of abdominal distension (organomegaly, ascites)
• Hypothyroidism
• Pituitary tumor causing hyperprolactinemia (rare)

CBC/Biochemistry/Urinalysis

• Normocytic, normochromic anemia-17–21% decrease in PCV during late diestrus.
• Hypercholesterolemia-75–94% increase during diestrus.

Other Laboratory Tests

Serum progesterone concentrations elevated if tested during diestrus.

Imaging

• Ultrasonographic findings-uterine enlargement; performed after 25 days from mating; can be use to evaluate pregnancy status and uterine fluid accumulation.
• Radiographic findings-normal; performed after 54 days from mating; can be used to evaluate presence of fetal skeletons and uterine fluid accumulation.

Diagnostic Procedures

N/A

Pathologic Findings

N/A

Appropriate Health Care

• Usually no treatment needed.
• Outpatient treatment for medical management of clinical signs of false pregnancy.

Nursing Care

• Prevent mammary gland stimulation from self-nursing with Elizabethan collar.
• Owners can cold pack mammary glands to reduce mammary gland activity.

Activity

Increase activity in sedentary dogs and cats to increase caloric expenditure and decrease calories available for lactation.

Diet

Decrease caloric intake for several days to reduce energy available for lactation.

Client Education

• False pregnancies are normal in bitches and do not impact future fertility.
• Advise cat owners that pyometra can develop following spontaneous ovulations.

Surgical Considerations

• OVE or OHE if bitch or queen is not intended for use in a breeding program.
• Perform OVE or OHE during anestrus or early diestrus when possible.

Drug(s) Of Choice

• Dopamine agonists-reduce milk production and some maternal behaviors by inhibiting prolactin release.
• Cabergoline 5 µg/kg PO q24h for 5–7 days
• Bromocriptine 10 µg/kg PO q8h for 5–7 days.

Contraindications

Dopamine agonists can cause abortion if given to a pregnant bitch or queen as prolactin is luteotrophic. Drugs that suppress prolactin will terminate pregnancy by reducing progesterone and can cause premature parturition (abortion).

Precautions

• Incidence of vomiting with bromocriptine administration reduced if given with food; cabergoline has fewer side effects and higher efficacy, but is more costly.
• Coat color changes in dogs possible with prolonged dopamine agonist treatment (uncommon).

Possible Interactions

Avoid acepromazine and metoclopramide; both can promote lactation and reduce the efficacy of dopamine agonists.

Alternative Drug(s)

• Short-term therapy with diazepam can be useful for bitches with extreme behavioral signs.
• Mibolerone 16 µg/kg PO q24h for 5–7 days to reduce symptoms of false pregnancy. Can also be used at 2.6 µg/kg/day starting at least 1 month prior to the next heat cycle to suppress estrus in bitches, which will prevent recurrence. Side effect and risks of treatment should be explained and owners should give informed consent prior to treatment. Do not give to cats.

Patient Monitoring

Have owners monitor mammary glands for inflammation and discoloration that could indicate mastitis.

Prevention/Avoidance

• Perform OVE or OHE during anestrus or early diestrus when possible.
• Estrus suppression.

Possible Complications

Mastitis with significant mammary gland hypertrophy, galactostasis, and ascending infection.

Expected Course and Prognosis

• Typically resolves in 2–4 weeks without treatment.
• Resolution in 5–7 days with dopamine agonist or mibolerone.
• May recur after any ovulation.

Associated Conditions

N/A

Age-Related Factors

N/A

Zoonotic Potential

N/A

Pregnancy/Fertility/Breeding

• The tendency to display overt false pregnancies has no impact on fertility.
• Bitches and queens should be evaluated for possible pregnancy before treating for false pregnancy.

Synonyms

• Pseudopregnancy
• Pseudocyesis
• Pseudo-gestation
• False-whelping

Abbreviations

• OHE = ovariohysterectomy
• OVE = ovariectomy
• PCV = packed cell volume

Internet Resources

• Gobello C, Concannon PW, Verstegen J. Canine pseudopregnancy: A review. In: Concannon PW, England G, Verstegen III J, Linde-Forsberg C, eds., Recent Advances in Small Animal Reproduction. International Veterinary Information Service, Ithaca NY, www.ivis.org; A1215.0801.
• Marti JA. Clinical aspects of mammary disease in the bitch and queen. Proceedings of the Southern European Veterinary Conference & Congreso Nacional AVEPA, 2009. International Veterinary Information Service, Ithaca, NY, www.ivis.org/proceedings/sevc/2009/eng/arus1.pdf.

Client Education Handout Available Online