• Pyometra is a common disorder associated with the luteal period.
  • The pathogenesis of pyometra is probably not rooted in the luteal phase, but in the multiple exposures to estrogen when the queen is cycling frequently and not induced to ovulate. This repeated exposure to estrogen results in endometrial hyperplasia.
  • The endometrial hyperplasia predisposes queens to pyometra when a luteal phase occurs. In one study, almost all queens greater than five years old (the mean age being 6.3 years) had evidence of endometrial hyperplasia.
  • The mean age of queens with pyometra is 7.2 to 7.6 years.
Clinical Signs
  • The primary clinical signs of pyometra include abdominal distension, vaginal discharge, anorexia, weight change and lethargy.
  • Queens with corpora lutea on the ovaries have a neutrophilic leukocytosis with a total white count averaging 57,000/l, whereas those without corpora lutea have a white count averaging 25,000/l.
  • Abdominal radiographs or ultrasound will help in determining if the uterus is enlarged.
  • Only about 20% of queens with pyometra have bacteriologic growth from the pyometra fluid.
  • The most commonly isolated organisms is Eschericha coli.
  • Treatments for pyometra include ovariohysterectomy, prostaglandins and surgical uterine lavage.
  • Ovariohysterectomy is the treatment of choice for queens that are not intended for breeding.
  • For queens with breeding potential, medical treatment with prostaglandins is preferred. 
    • Prostaglandin F2alpha at a dosage of 200 g/kg/day IM for 2 days followed by 500 g/kg/day for 3 days combined a with broad spectrum antibiotic is an effective treatment and can restore fertility. 
    • An increase in vaginal discharge is often noted within 15 minutes to 3 hours after treatment. 
    • Transient side effects with prostaglandin treatment include defecation and vomiting. 
    • Relative circulatory hypovolemia, as seen in the dog following prostaglandin therapy, has not been reported in the cat. The side effects and vaginal discharge usually diminish with each subsequent treatment.
  • Because of the reported success of prostaglandin therapy for pyometra, treatment by surgical uterine lavage may only be warranted for those cases refractory to prostaglandin treatment.
  • Prevention of pyometra includes strategies to minimize the number of exposures to estrogen dominance. These strategies include inducing ovulation, breeding at estrus to keep the queen pregnant or in pseudopregnancy, manipulating lighting so the queen will remain in anestrus, or preventing estrus pharmacologically.

Other Diseases
  • Other diseases seen during the luteal phase include endometritis and hydrometra.
  • Endometritis may be an early stage in the development of pyometra as clinical signs may be similar, but the uterine pathology is not as severe.
  • Hydrometra is a collection of nonpurulent fluid in the uterus. These two conditions are treated the same as pyometra.
Fibroadenometous Mammary Hyperplasia


  • Click here to go to Brazilian study and see a picture.
  • Fibroadenometous mammary hyperplasia is characterized by the enlargement of the mammary glands resulting from the progesterone phase in young queens (pregnancy or pseudopregnancy) and exogenous progestagens in older queens.
  • The enlarged mammary glands are very firm and may succumb to secondary mastitis or traumatic ulceration.
  • Regression has been reported following pregnancy and lactation.
  • Since this condition is associated with progesterone domination, the treatment of choice should eliminate the progesterone stimulation by ovariohysterectomy.
    • 10 mg/kg aglepristone (Alizine; Virbac), a progesterone-receptor blocker, for five consecutive days and then again on the seventh day has been reproted to help.
      • Two days after the onset of treatment, a reduction in the size of the mammary glands was observed
      • Significant regression was seen on day 6.
      • Complete involution of the glands was achieved four weeks after the initial treatment
      • Lower doses of (0.1 mg/kg s.c. q24 hrs and then 5.0 mg/kg s.c three weeks later) have reported efficacious.
  • Surgery during the acute phase is not warranted as the condition normally will subside spontaneously. Administration of progestational hormones should be avoided.

contributed by Bruce E Eilts and modified 13 February 2012

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contributed by Bruce E Eilts on 25 September 2012


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