Overview

• Bacterial uterine infection that develops in the immediate postpartum period (usually within the first week); occasionally develops after an abortion or non-sterile artificial insemination-rarely after natural breeding.
• Bacteria-ascend through the open cervix to the uterus; a large, flaccid, postpartum uterus provides an ideal environment for growth; gram-negative bacteria (e.g., Escherichia coli) commonly isolated.
• Potentially life-threatening infection; may lead to septic shock.
• Directly affects uterus; systemic involvement as sepsis develops.
• Can become chronic and lead to infertility.

Signalment

• Postpartum bitch and queen
• No age or breed predilection

Signs

Causes & Risk Factors

• Dystocia
• Obstetric manipulation
• Retained fetuses or placentas
• Prolonged delivery (large litter)
• Post-abortion, and post-natural or artificial insemination (rare)

Differential Diagnosis

• Subinvolution of placental sites-no sign of infection on cytologic examination of vagina.
• Eclampsia-differentiated by serum calcium concentration.
• Mastitis-differentiated by physical examination findings.

CBC/Biochemistry/Urinalysis

• Neutrophilia with left shift.
• Leukopenia-occasionally with endotoxic shock.
• High PCV, total protein, creatinine, BUN, and urine specific gravity-secondary to dehydration. Normocytic, normochromic nonregenerative anemia may also occur.
• High liver enzyme-with endotoxemia.
• Low urine specific gravity-may see with endotoxemia.
• Hypoabluminemia, elevation of C-reactive protein, and acute phase proteins may occur.
• Urinalysis may reveal isosthenuria, bacteruria (obtain via U/S guided cystocentesis).

Other Laboratory Tests

N/A

Imaging

• Radiography-reveals a large uterus and possibly retained fetus(es).
• Ultrasonography-reveals intrauterine fluid accumulation and increased horn width, retained placenta(s), and retained fetus(es); shows abdominal effusion secondary to uterine rupture.

Diagnostic Procedures

• Vaginal cytologic examination-detect degenerative neutrophils with intracellular and extracellular bacteria.
• Guarded anterior vaginal or transcervical culture-aerobes and anaerobes; identify organism and its antibiotic sensitivity pattern.

Drug(s)

• Antibiotics-start with broad-spectrum agents (oral if patient is stable; intravenous if patient is in shock); choice confirmed by bacterial culture and sensitivity; continued at least 14 days. Give at separate time from PGF₂ administration due to risk of vomiting.
• Nursing planned-amoxicillin-clavulanic acid (dogs, 12.5–25 mg/kg PO q12h; cats, 62.5 mg/cat PO q12h); can administer q8h with Gram-negative infections; or oxacillin (22–40 mg/kg PO q8h) to start.
• Nursing not planned-enrofloxacin (2.5–10 mg/kg PO q12h) to start.
• Oxytocin 0.5–1 U/kg IM (do not exceed 20 IU total); then repeat in 1–2 hours; may note inadequate response if >48 hours since parturition.
• PGF₂ 10–50 µg/kg SC q3–5h for 3–5 days or 100 µg/kg SC q12h for 3–5 days; to evacuate uterus, ultrasound prior to cessation of treatment to ensure resolution of fluid accumulation in uterine lumen.

Contraindications/Possible Interactions

• Prostaglandin-may induce uterine rupture if the tissue is devitalized.
• Oxytocin-not effective beyond 48 hours postpartum.
• Uterine flushing-may cause rupture of devitalized wall.

Patient Monitoring

• CBC, temperature, vaginal cytologic examination, and clinical signs.
• Ultrasonography-monitor evacuation of uterine fluid.

Possible Complications

• Ovariohysterectomy-necessary when medical treatment is ineffective.
• Uterine rupture and peritonitis-may occur with medical treatment.
• Owners may need to foster or hand-raise puppies and kittens, monitor daily weight gain to ensure adequate nutrition: pups should gain 10% of birth weight per day; kittens should gain a minimum of 7–10 g/day.

Expected Course and Prognosis

• Ovariohysterectomy-prognosis for recovery good; recommended for older patients.
• Medical treatment-prognosis for recovery dependent on early recognition of problem by owner-good if early, may adversely affect future reproduction.

Abbreviations

• PCV = packed cell volume
• PGF₂ = prostaglandin F₂