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Standards of Care December 2008 (Vol 10, No 11)

Acute Metritis

by Autumn P. Davidson, DVM, MS, DACVIM (Internal Medicine), Tomas Baker, MS

    CETEST This course is approved for 1.0 CE credits

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    Acute infection of the postpartum endometrium should be suspected if lethargy, anorexia, decreased lactation, and poor mothering occur accompanied by fever and malodorous vaginal discharge. Metritis is serious and sometimes preceded by dystocia, contaminated obstetric manipulation, or retained fetuses and/or placentas. Bacterial ascension from the lower genitourinary tract is more common than hematogenous origin, and Escherichia coli is the most common causative organism in both bitches and queens. Metritis can become chronic and cause infertility.

    Diagnostic Criteria

    Historical Information

    Gender Predisposition

    • Intact, postpartum female.

    Age/Breed Predisposition

    • None.

    Owner Observations

    • Lethargy.
    • Deterioration in maternal behavior.
    • Partial to total anorexia.
    • Malodorous vaginal discharge.
    • Diminished lactation.

    Other Historical Considerations/Predispositions

    • Prolonged or difficult labor (dystocia).
    • Contaminated obstetric intervention.
    • Placental or fetal retention.
    • Intrauterine death of fetus(es).
    • Septic mastitis.

    Physical Examination Findings

    • Copious, malodorous vaginal discharge in the postpartum period. Normal postpartum discharge (lochia) is not odorous.
    • Fever.
    • Lethargy.
    • Diminished lactation.
    • Signs of sepsis if advanced: hypovolemia, tachycardia, injected mucous membranes, weakness.
    • Persistent palpably enlarged uterus (lack of normal involution).

    Laboratory Findings

    Blood work.

    • Hemogram:
      — Neutrophilia with left shift (may be degenerative) or neutropenia. Hemogram can be normal early in the course of metritis.
      — Anemia (of pregnancy and chronic illness).
    • Chemistry panel:
      — Hypoalbuminemia.
      — Hyperglobulinemia.
      — Hypoglycemia in more severely affected dams may indicate sepsis.
    • Coagulopathy in more severely affected dams may indicate sepsis.
    • Cytology of vaginal discharge demonstrates neutrophilic inflammation with both extracellular and intracellular bacteria (septic inflammation). Normal postpartum lochia can be neutrophilic and hemorrhagic but without evidence of sepsis.
    • Aerobic and anaerobic culture of the cranial vagina is often positive for a single organism rather than normal mixed vaginal flora.

    Other Diagnostic Findings

    • Abdominal ultrasonography:
      — Fluid-filled uterine horns that do not decrease in size over time as anticipated during normal postpartum involution (Figures 1 and 2).
      — Retained placenta(s) or fetus(es).
      — Evidence of peritonitis (hyperechoic mesentery, ascites).
    • Radiography is of limited use.
    Figure 1: Acute Metritis
    Figure 2: Acute Metritis

    Summary of Diagnostic Criteria

    • Febrile, inappetent, lethargic, postpartum bitch or queen with malodorous vaginal discharge.
    • Cytology of vaginal discharge demonstrates septic inflammation.
    • Positive aerobic or anaerobic culture of the cranial vagina.
    • Complete blood count consistent with acute inflammation or sepsis.
    • Ultrasound images demonstrating an abnormal amount of fluid within the uterine lumen, lacking typical involution of the postpartum uterus.

    Diagnostic Differentials

    • Normal lochia—vaginal discharge is not purulent, septic, or malodorous.
    • Subinvolution of placental sites—vaginal discharge is hemorrhagic, nonpurulent, and nonseptic.
    • Vaginitis, cystitis, urethritis—vaginal discharge is scant.
    • Coagulopathy causing prolonged postpartum hemorrhage—vaginal discharge is hemorrhagic.
    • Retained or macerated fetus—seen with ultrasonography.
    • Retained placenta—seen with ultrasonography.
    • Uterine torsion—"acute abdomen," rapid clinical deterioration, confirmed with ultrasonography.
    • Uterine rupture/peritonitis—"acute abdomen," rapid clinical deterioration, confirmed with ultrasonography.

    Treatment Recommendations

    Initial Treatment

    • Broad-spectrum bactericidal antibiotics should be initiated while awaiting culture and sensitivity results. $
      — IV delivery of antibiotics is indicated if the dam is significantly ill or septic. $$
      — If the dam is eating and relatively stable, oral administration of antibiotics can be attempted. $
      — The decision to treat the dam as an outpatient, permitting her to continue nursing the neonates, should be based on her status. Nursing is advised only if the dam is stable and responding to outpatient therapy and the neonates continue to thrive (weight gain, vigorous). If nursing continues, the selection of antibiotics is limited to those noted to be safe for neonates with limited metabolic capabilities.
      — First-generation cephalosporins (cephalexin 20 mg/kg PO or IV q8h for 14+ days) or potentiated penicillins, amoxicillin with clavulanic acid (dose based on the amoxicillin fraction; 12-13.75 mg/kg PO for 14+ days), or ticarcillin with clavulanic acid (50 mg/kg of ticarcillin with 1.7 mg/kg of clavulanic acid IV or IM q6-8h). $$
      — If culture and sensitivity results dictate the use of antibiotics contraindicated for nursing puppies and kittens (e.g., fluoroquinolones), the neonates should be weaned and given supplemental feeding. Veterinarians should consult the package insert or Physicians' Desk Reference (PDR) for potential adverse effects of any drug they contemplate giving a nursing dam.
    • Hospitalization with supportive care as indicated by the dam's condition (e.g., intravenous fluids). $$$
    • Prostaglandin therapy for uterine evacuation. $
      — Prostaglandin F2-α (Lutalyse, Pharmacia): 0.10-0.20 mg/kg SC q12-24h to effect.
      — Cloprostenol (Estrumate, Schering): 1-3 μg/kg SC q24h to effect (fewer adverse effects).

    Alternative/Optional Treatments/Therapy

    • Ovariohysterectomy once stabilized. $$
    • Neonates should be hand raised and fed if the dam's condition is serious. $$

    Supportive Treatment

    • Hospitalization for supportive care: IV fluids and parenteral antibiotics if indicated by the dam's condition.
    • Antiemetics (metoclopramide: 0.1-0.2 mg/kg SC or PO bid) can be used if nausea occurs in association with the use of prostaglandins. (The antiemetic must be safe for neonates if nursing is continued.) $

    Patient Monitoring

    • Serial ultrasonography to evaluate the size of the uterine horns and fluid content of the uterine lumen (Figures 1, 2, 3, and 4).
    • Serial physical examination to evaluate clinical signs and vital parameters.
    • Serial blood work, as appropriate for the patient's condition, to evaluate complete blood count and resolution of biochemical and coagulation abnormalities.
    • Serial vaginal discharge cytology to evaluate amount and degree of inflammation.
    Figure 3: Acute Metritis
    Figure 4: Acute Metritis

    Home Management

    • Administration of antibiotics as prescribed, including the complete duration as indicated.
    • Prostaglandin therapy can be conducted on an outpatient basis in stable dams so they may continue to nurse neonates. However, all prostaglandin therapy should be administered in the hospital due to the narrow therapeutic range and potentially life-threatening adverse effects.
    • Consider the use of probiotic supplements if diarrhea occurs in association with the use of antibiotics.
    • Feedings should be timed to minimize nausea from prostaglandin administration.
    • Good hygiene of the whelping or queening box should be maintained.
    • Neonatal monitoring (daily weight, vigor, normal behavior) is essential due to the dam's condition.

    Milestones/Recovery Time Frames

    • Clinical improvement is anticipated within 24 hours of the initiation of appropriate therapy.
    • Resolution of uncomplicated postpartum metritis (no fetal or placental remnants) with medical therapy (antibiotics and prostaglandins) is usually quicker than resolution of pyometra because no luteal production of progesterone is present.
    • Prostaglandin therapy can be necessary for 3 to 7+ days. The duration is dictated by ultrasound findings, laboratory test results, and clinical signs.

    Treatment Contraindications

    • Oxytocin is unlikely to promote effective uterine evacuation when administered >24 to 48 hours postpartum.
    • Any drug administered to a nursing dam will be administered to the nurslings as well. Drugs can be concentrated in milk, resulting in increased doses to the nurslings. Nephrotoxic and hepatotoxic drugs should be avoided.
      — NSAIDs (immature neonatal renal and hepatic development).
      — Aminoglycosides (nephrotoxicity).
      — Sulfa drugs (myelotoxicity).
      — Chloramphenicol (myelotoxicity).
      — Fluoroquinolones (arthropathy).
      — Antiemetics not known to be safe in nursing dams (always consult the package insert or PDR).


    Favorable Criteria

    • Early recognition and intervention.
    • Response to antibiotics and prostaglandin administration.
    • Return of normal appetite and maternal behavior.
    • Lack of fever.
    • Lack of toxic neutrophils, hypoglycemia, or leukopenia.

    Unfavorable Criteria

    • Sepsis.
    • Peritonitis.
    • Fetal or placental retention.
    • Concurrent disease affecting the immunocompetency of the dam.
    • Concurrent mastitis.

    Grundy SA, Davidson AP. Acute metritis secondary to retained fetal membranes and a retained nonviable fetus. Theriogenology question of the month. JAVMA 2004;224(6):844-847.

    Feldman EC, Nelson RW. Periparturient diseases. In: Canine and Feline Endocrinology and Reproduction. 3rd ed. Philadelphia: Elsevier; 2007:827-828.

    Johnston SD, Root Kustritz MV, Olson PN. Diseases of the canine uterus and uterine tubes (oviducts). In: Canine and Feline Theriogenology. Philadelphia: Elsevier; 2003:206-224.

    Johnston SD, Root Kustritz MV, Olson PN. Periparturient disorders in the bitch. In: Canine and Feline Theriogenology. Philadelphia: Elsevier; 2003:129-145.

    Watts JR, Wright PJ, Lee CS, Whitehear KG. New techniques using transcervical uterine cannulation for the diagnosis of uterine disorders in bitches. J Reprod Fertil 1997;51(suppl):283-293.

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    CETEST This course is approved for 1.0 CE credits

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