False Pregnancy

False Pregnancy – An Overview

  • Display of maternal behavior and physical signs of pregnancy 2–3 months after “heat” or “estrus” by a non-pregnant bitch
  • Physical, hormonal, and behavioral changes following an unsuccessful mating or spontaneous ovulation in the queen; “ovulation” is the release of the egg from the ovary
  • A female dog is a “bitch”
  • False pregnancy also known as “pseudopregnancy,” “phantom pregnancy,” or “pseudocyesis”

Signalment/Description of Pet

Breed Predilections

  • None

Mean Age and Range

  • Any age

Predominant Sex

  • Female
  • Non-pregnant bitches that were in heat or estrus 2–3 months earlier and that are experiencing a decline in serum progesterone concentration; “progesterone” is the female hormone that supports and maintains pregnancy in a pregnant pet—it normally remains high in non-pregnant bitches for several weeks following their heat or estrous cycles

Signs/Observed Changes in Pet

  • Severity variable among individuals and from one occurrence to the next within the same individual
  • Behavior changes—nesting, mothering activity (such as mothering a stuffed toy or unrelated puppies), restlessness, and self-nursing
  • Aggression
  • Sluggishness (lethargy)
  • Abdominal distention (rare) and breast or mammary gland enlargement
  • Weight gain
  • Vomiting, depression, and lack of appetite (known as “anorexia”)
  • Large mammary glands that secrete a clear to milky to brownish fluid

Causes

  • False pregnancy is a normal phenomenon in bitches following ovulation (release of the egg from the ovary)
  • Progesterone and prolactin—drop in progesterone concentration causes prolactin concentration to rise; “progesterone” is the female hormone that supports and maintains pregnancy in a pregnant pet—it normally remains high in non-pregnant bitches for several weeks following heat or estrus; “prolactin” is a hormone that stimulates breast or mammary gland enlargement and milk production (known as “lactation”)
  • Treatment with progestin (substance capable of producing the effects of the female hormone, progesterone) for conditions not related to false pregnancy—may develop signs of false pregnancy after drug withdrawal
  • Surgical removal of the ovaries (known as “oophorectomy” or “ovariectomy”) or the ovaries and uterus (known as “ovariohysterectomy” or “spay”) during the period when progesterone levels are high following heat or estrus—may develop signs of false pregnancy 3–4 days following surgery due to the sudden drop in progesterone
  • Inadequate levels of thyroid hormone (known as “hypothyroidism”) with high thyroid-stimulating hormone (TSH) concentration in the blood, which stimulates prolactin secretion—may note some associated clinical signs

Risk Factors

  • Ovariectomy or ovariohysterectomy or spay performed during the period when progesterone levels are high following heat or estrus
  • Treatment with progestins
  • Not thought to be influenced by previous pregnancy
  • Does not cause susceptibility to other reproductive diseases

Treatment

Health Care

  • Usually no treatment needed—all pregnant, non-pregnant, and false-pregnant ovulating dogs go through a similar stage of high progesterone levels following heat or estrus
  • Outpatient for medical treatment
  • Inpatient—planned surgery
  • Progestins (substances capable of producing the effects of the female hormone, progesterone) and androgens (male hormones) to decrease secretion of prolactin; “prolactin” is a hormone that stimulates breast or mammary gland enlargement and milk production (lactation)
  • Surgical removal of the ovaries and uterus (ovariohysterectomy or spay) during anestrus (the time between heat or estrous cycles)—prevents recurrence
  • Mammary glands—minimize stimuli that promote milk production (lactation); use cold packs applied to the breasts or mammary glands
  • Elizabethan collar—prevent self-nursing or licking; but even rubbing of the collar on the mammary glands may be sufficient to prolong milk production (lactation)

Diet

  • Reduction of food for several days may reduce milk production (lactation)

Surgery

  • Surgical removal of the ovaries and uterus (ovariohysterectomy or spay)—if the bitch or queen is not intended for breeding; recommended during the next anestrus (the time between heat or estrous cycles), when possible

Medications

Medications presented in this section are intended to provide general information about possible treatment. The treatment for a particular condition may evolve as medical advances are made; therefore, the medications should not be considered as all inclusive.

  • Cabergoline (Dostinex)—a prolactin inhibitor; “prolactin” is a hormone that stimulates breast or mammary gland enlargement and milk production (lactation)
  • Bromocriptine (Parlodel)—not approved for veterinary use in the United States and Canada; will reduce milk production (lactation) by 89% and decrease behavioral signs of false pregnancy by 90%
  • Diazepam—medication used to decrease anxiety; short-term treatment for bitches with extreme behavioral signs
  • Mibolerone—to reduce signs of false pregnancy in bitches; should not be used in queens

Follow-Up Care

Patient Monitoring

  • Surgical removal of the ovaries (ovariectomy) or ovaries and uterus (ovariohysterectomy or spay) during anestrus (the time between heat or estrous cycles)—prevents recurrence
  • “Heat” or estrus suppression

Expected Course and Prognosis

  • Usually resolves in 2–4 weeks without treatment
  • Treatment with bromocriptine, cabergoline, or mibolerone—may resolve condition in 5–7 days
  • False pregnancy may develop during subsequent heat or estrous cycles
  • False pregnancy does not impact future fertility

Key Points

  • False pregnancy is a normal phenomenon in bitches following ovulation (release of the egg from the ovary)
  • False pregnancies do not impact future fertility
  • Bitches should be evaluated for actual pregnancy before treating for false pregnancy
  • No association has been identified between false pregnancy and reproductive abnormalities
  • Pyometra (inflammation with accumulation of pus in the uterus) can develop in queens following spontaneous ovulation (release of the egg from the ovary)

Pyometra

Pyometra – An Overview

  • Cystic endometrial hyperplasia—hormonally mediated, progressive, abnormal thickening in the lining of the uterus (known as the “endometrium”), characterized by the presence of fluid-filled sacs or cysts
  • Pyometra—develops secondary to cystic endometrial hyperplasia or inflammation of the lining of the uterus (known as “endometritis”); develops when bacteria invade the abnormally thickened lining of the uterus (lining of the uterus known as the “endometrium”) and pus accumulates in the uterus
  • The female dog is a “bitch”

Signalment/Description of Pet

Mean Age and Range

  • Usually greater than 6 years of age
  • Young pets—especially if treated with female hormones (estrogen) or progestogen (any substance capable of producing the effects of the female hormone, progesterone)
  • Usually diagnosed 1–12 weeks after “heat” or “estrus”
  • Accumulation of pus in the uterine stump (known as “pyometra of the uterine stump”) in spayed pets—may develop any time after surgical removal of the ovaries and uterus (known as a “spay” or “ovariohysterectomy”)

Predominant Sex

  • Female only

Signs/Observed Changes in Pet

  • Closed cervix (the “cervix” is the lower part of the uterus that extends into the vagina [the tubular passageway or birth canal, leading from the opening of the vulva to the cervix]; a “closed cervix” is one in which the muscles surrounding the cervix are contracted and the opening into the uterus is “shut” so no pus or discharge can drain from the uterus—signs of generalized (systemic) illness, progressing to signs of generalized disease caused by the spread of bacteria in the blood (known as “septicemia” or “blood poisoning”) and shock
  • Uterus—enlarged with closed cervix (where the pus or discharge cannot drain from the uterus); may not be enlarged with open cervix (where the muscles surrounding the cervix are relaxed, allowing the opening into the uterus to expand and pus or discharge to drain from the uterus, through the vagina and vulva [external genitalia])
  • Discharge from the vulva (external genitalia)—depends if cervix is open or closed; discharge may be bloody or may contain mucus and pus
  • Depression and sluggishness (lethargy)
  • Lack of appetite (known as “anorexia”)
  • Increased urination (known as “polyuria”) and increased thirst (known as “polydipsia”)
  • Vomiting
  • Abdominal distension

Causes

  • repeated exposure of the lining of the uterus (endometrium) to estrogen followed by exposure to progesterone with each “heat” or “estrus” (whether or not the bitch becomes pregnant); this hormonal pattern is unique to the bitch

Treatment

Health Care

  • Inpatient
  • Accumulation of pus in the uterus (pyometra)—life-threatening condition if the cervix is closed (where pus or discharge cannot drain from the uterus)
  • Supportive care—immediate intravenous fluid administration and antibiotics

Surgery

  • Accumulation of pus in the uterus (pyometra), open and closed cervix—surgical removal of the ovaries and uterus (spay or ovariohysterectomy) preferred treatment; long-term (chronic) progressive disease
  • Accumulation of pus in the uterus (pyometra), with a closed cervix (where pus or discharge cannot drain from the uterus)—caution should be used during surgical removal of the ovaries and uterus (spay or ovariohysterectomy); the enlarged uterus may be very fragile
  • Uterine rupture or leakage of pus from the uterine stump—repeated flushing (lavage) of the abdominal cavity with sterile saline

Medications

Medications presented in this section are intended to provide general information about possible treatment. The treatment for a particular condition may evolve as medical advances are made; therefore, the medications should not be considered as all inclusive.

Antibiotics

  • Initial antibiotic selected by your pet’s veterinarian based on experience, pending results of bacterial culture and sensitivity test
  • Should be administered to all pets with inflammation characterized by accumulation of pus in the uterus (pyometra)
  • Common choices—ampicillin; enrofloxacin (Baytril®)
  • Antibiotics—not effective as the sole treatment, unless the uterus is of normal size and the serum progesterone level is less than 2 ng/ml on blood tests

Prostaglandins

Prostaglandin F2a (PGF2a)

  • Prostaglandins cause smooth muscle contractions and subsequent emptying of the uterus and decrease in serum progesterone concentration, based on dosage
  • For 2–7 days, until the uterus nears normal size as determined by feeling the abdomen, x-rays, or ultrasound examination or until no fluid is visible within the uterus as seen by ultrasound examination
  • Reevaluate the pet 2–4 weeks after discontinuation of prostaglandins; if the uterus has increased in size or the pet still has marked discharge from the vulva (external genitalia), medical treatment protocol can be repeated
  • Surgical removal of the ovaries and uterus (spay or ovariohysterectomy)—performed in pets that do not respond to treatment with prostaglandin (lack of response indicated by continued enlargement of the uterus or presence of fluid in the uterus, or discharge from the vulva is still present after two courses of medical treatment)

Closprostenol

  • Injection under the skin (subcutaneous or SC injection) daily for 7–14 days

Miscellaneous

  • Aglepristone—effectiveness improved with prostaglandin treatment at the same time; not readily available in the United States
  • Cabergoline—for 7–14 days with prostaglandin treatment
  • Drugs that enhance the immune response (such as estrogens) or certain agents (such as oxytocin and ergot), which induce contraction of the muscles of the uterus are unreliable; “oxytocin” is a female hormone that causes uterine contractions and promotes milk release during lactation

Follow-Up Care

Patient Monitoring

  • Release from the hospital when the uterus is of near normal size or when no fluid is visible within the uterus by ultrasound examination, and clinical signs have lessened in severity or disappeared; reevaluate in 2–4 weeks
  • Antibiotics—administration should be continued for 3–4 weeks
  • Discharge from the vulva (external genitalia)—may persist for up to 4 weeks
  • Serial complete blood counts (CBCs)—the white blood cell (WBC) count rises rapidly after surgical removal of the ovaries and uterus (spay or ovariohysterectomy), because the bone marrow continues to release neutrophils (a type of white blood cell) into the bloodstream, from which they can no longer enter the uterus

Preventions and Avoidance

  • Next proestrus (time from beginning of vaginal bleeding of “heat” until the bitch allows male to mount and breed)—obtain a specimen of the anterior vagina for bacterial culture, using a guarded culture swab
  • Treat bitch with an appropriate antibiotic for 3 weeks
  • Breed during the “heat” or “estrus” immediately following medical treatment—the pregnant uterus may be less susceptible to reinfection; bitch with underlying cystic endometrial hyperplasia has limited breeding life (best to get desired number of puppies as soon as possible); bitch not more likely to clear the disease spontaneously if allowed to cycle without being bred

Possible Complications

  • Bitch may enter “heat” or “estrus” sooner after medical treatment than anticipated
  • Accumulation of pus in the uterus (pyometra)—life-threatening condition if the cervix is closed (where pus or discharge cannot drain from the uterus)

Expected Course and Prognosis

  • Underlying cystic endometrial hyperplasia (thickening of the uterine lining with the presence of fluid-filled sacs or cysts) still exists; predisposed to recurrence
  • Breed bitch to desired stud dogs in a timely manner; use of subfertile stud dogs is not recommended
  • Recommend surgical removal of ovaries and uterus (spay or ovariohysterectomy) as soon as breeding life is over
  • Closed-cervix (where pus or discharge cannot drain from the uterus) inflammation of the uterus with accumulation of pus (pyometra) can be associated with uterine rupture and inflammation of the lining of the abdomen (known as “peritonitis”)

Key Points

  • Surgical removal of ovaries and uterus (spay or ovariohysterectomy) is the preferred treatment
  • Medical treatment should be considered only for a valuable breeding animal that has an open cervix (where pus or discharge can drain from the uterus) and does not have excess levels of urea and other nitrogenous waste products in the blood (known as “uremia” or “azotemia”); except when breeding is planned, non-progestational, estrus-suppressing drugs must be given for life
  • Medical treatment of closed-cervix (where pus or discharge cannot drain from the uterus) inflammation of the uterus with accumulation of pus (pyometra) can be associated with uterine rupture and inflammation of the lining of the abdomen (peritonitis)
  • Medical treatment probably does not cure underlying cystic endometrial hyperplasia (thickening of the uterine lining with the presence of fluid-filled sacs or cysts) in pets with either open- or closed-cervix pyometra, but may enable some affected bitches to reproduce