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Basics ⬇

Outline

BASICS

Definition!!navigator!!

Fetal membranes not been passed by 3 h postpartum.

Pathophysiology!!navigator!!

Suggested Causes

  • Pathologic adherence between the endometrium and chorion; possible recurrence with future pregnancies.
  • Infections between endometrium and chorion.
  • Any debilitating condition of the mare

Systems Affected!!navigator!!

Reproductive

Incidence/Prevalence!!navigator!!

  • Most common postpartum condition, 2–10% incidence.
  • Increased incidence after dystocia or Caesarean section; in draft mares; a hydrops pregnancy; after prolonged pregnancy mares >15 years

Signalment!!navigator!!

All females of breeding age.

Signs!!navigator!!

General Comments

  • RFM visible at vulvar lips—an unreliable indicator of the portion retained within the uterus.
  • With mare movement, portions of membranes tear free.
  • Search stall bedding for additional placental pieces

Historical Findings

  • Previous history of RFM.
  • No effect—previous year's reproductive status, breeding method, sex of foal, birth of a weak foal or dead fetus

Physical Examination Findings

  • Transrectal palpation—determine uterine size and tone, gauge fluid volume in the uterine lumen.
  • Vaginal examination not always essential—depends on mare's general health, condition of the placenta and uterus

Causes!!navigator!!

See Pathophysiology.

Risk Factors!!navigator!!

See Historical Findings.

Diagnosis ⬆ ⬇

Outline

DIAGNOSIS

Differential Diagnosis!!navigator!!

  • Uterine infection.
  • Delay or failed postpartum involution

Pathologic Findings!!navigator!!

See Pathophysiology.

Treatment ⬆ ⬇

Outline

TREATMENT

Appropriate Health Care!!navigator!!

  • Oxytocin—best results.
  • Start oxytocin treatment ≤3 h postpartum if RFM
    • Repeat every 60–120 min for the first 12–18 h postpartum.
  • If >12–18 h, consider treating with intrauterine irritants, antibiotics, or prostaglandins.
  • Systemic antibiotics if systemic disease.
  • Uterine lavage of value if a portion is retained.
  • Insufflation if membranes are largely intact. Place fluid (best—isotonic saline solution; alternatively lactated Ringer's solution or water) to dilate the uterine lumen within the innermost aspect of the fetal membranes; expand uterine lumen, stimulate uterine activity
    • Gather exposed (external to the vulvae) portion of RFM; tie around it outside of the vulvae to maintain fluid within the uterus and placenta for a brief time; this maintains uterine expansion, stretches myometrium/endometrium to facilitate release of the microvilli.
  • Isolate a vessel of the umbilical cord of RFM at the vulvar lips; transect and place a 9 mm (or small diameter, if necessary) nasogastric tube into the incision; attach a low-pressure volume source of fluid for approximately 5 min; this induces edema and swelling of placental tissue; facilitates separation from the endometrium

Nursing Care!!navigator!!

  • Administer oxytocin postpartum to all mares with a history of RFM.
  • Examine membranes after passage; confirm all portions are present

Activity!!navigator!!

Normal exercise.

Diet!!navigator!!

No changes are indicated.

Client Education!!navigator!!

  • RFM is relatively common; treat if not passed within 3 h postpartum, regardless of the time of day or night when foaling occurred.
  • Advise owners to maintain a supply of oxytocin; begin treatment only after 3 h have passed; start by 2.5 h if a draft horse breed

Medications ⬆ ⬇

Outline

MEDICATIONS

Drug(s) of Choice!!navigator!!

  • Oxytocin (20 IU IV or 40 IU IM per injection), repeat injections at 60–120 min intervals.
  • After 18–24 h—can administer prostaglandin F2α or analogs; antibiotics may be infused into uterus

Contraindications!!navigator!!

Higher doses of oxytocin may lead to uterine prolapse.

Precautions!!navigator!!

Oxytocin may induce uterine cramping, with potential to harm the foal.

Alternative Drugs!!navigator!!

None as effective as oxytocin.

Follow-up ⬆ ⬇

Outline

FOLLOW-UP

Patient Monitoring!!navigator!!

  • Examine mare—determine if placenta has been expelled.
  • Evaluate uterine size (involution) and tone—determine if normal relative to the number of days postpartum

Prevention/Avoidance!!navigator!!

  • Exercise and dietary supplementation with selenium may have value.
  • Avoid fescue pasture/hay near term

Possible Complications!!navigator!!

  • Septic metritis.
  • Laminitis

Expected Course and Prognosis!!navigator!!

  • Of mares treated with oxytocin, >90% pass RFM with no other problems; excellent prognosis.
  • RFM passed without secondary involvement have no effect on foal heat breeding conception.
  • Affected mares treated with intrauterine antibiotics—higher rates of conception but higher rates of early pregnancy termination

Miscellaneous ⬆ ⬇

Outline

MISCELLANEOUS

Associated Conditions!!navigator!!

See Historical Findings.

Age-Related Factors!!navigator!!

Old mares have a higher incidence on some farms.

Pregnancy/Fertility/Breeding!!navigator!!

RFM incidence may increase with parturition induction.

Synonyms!!navigator!!

Retained afterbirth

Abbreviations!!navigator!!

RFM = retained fetal membranes

Suggested Reading ⬆ ⬇

Blanchard TL, Varner DD. Postpartum septic/toxic metritis in the mare—observation & rationale for treatment. Clin Theriogenol 2011;3(3):3.

McNaughtyon JW, Meijer M, Macpherson ML. A novel approach to removing retained fetal membranes in the mare. Clin Theriogenol 2015;7(3):338.

Author(s) ⬆

Author: Carla L. Carleton

Consulting Editor: Carla L. Carleton

Acknowledgment: The author/editor acknowledges the prior contribution of Walter R. Threlfall