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Basics ⬇

Outline

BASICS

Definition!!navigator!!

  • Premature detachment of the CA membrane from the endometrium before delivery of the term fetus.
  • The CA is responsible for supplying the fetus with oxygen and nutrients and for removing its waste products; with PPS (e.g. parturition late stage 1, early stage 2), the fetus may die unless immediate aid in delivery is provided

Pathophysiology!!navigator!!

  • Proposed origins—alterations in the CA membrane in the area of the internal cervical os or abnormal attachment of the CA membrane to the endometrium, predisposing to PPS.
  • Occurs secondary to cervical relaxation (hormonal, ascending infection, cervical incompetency) and development of low-grade placentitis

Incidence/Prevalence!!navigator!!

  • Incidence increases significantly with induction of parturition.
  • Incidence of <1% in medium-sized to large breeds of horses; higher in miniature horses

Signalment!!navigator!!

All ages and breeds; increased occurrence in miniature horses.

Signs!!navigator!!

  • An emergency—abrupt reduction in O2 delivery to the fetus, immediate delivery assistance is essential as soon as the CA membrane protrudes through the vulvar lips.
  • Often a history of PPS.
  • Physical examination findings are normal.
  • CA membrane, when presented at the vulva, may appear to be characteristically red, velvety, and roughened

Causes!!navigator!!

  • Miniature horses.
  • Induction of parturition.
  • Older mares.
  • Placentitis, high-risk pregnancy

Risk Factors!!navigator!!

See Causes.

Diagnosis ⬆ ⬇

Outline

DIAGNOSIS

Differential Diagnosis!!navigator!!

  • Evagination of the vaginal wall.
  • Eversion of the urinary bladder.
  • Prolapse of the vaginal wall.
  • Lacerations of the vaginal wall and prolapse of the intestines

CBC/Biochemistry/Urinalysis!!navigator!!

N/A

Other Laboratory Tests!!navigator!!

N/A

Imaging!!navigator!!

US

  • Prepartum examination may reveal an area of detachment cranial to the cervix (ventral aspect of the uterine body and its placental attachment), which also may indicate a mare at risk for placentitis; record combined thickness of uterus and placenta to assess the severity of placentitis.
  • Intrapartum appearance of the CA membrane protruding through the vulvar lips (i.e. “red velvet” or “red bagging”) is diagnostic in itself.

Other Diagnostic Procedures!!navigator!!

Best diagnostic method—visual examination of the exposed tissue.

Pathologic Findings!!navigator!!

N/A

Treatment ⬆ ⬇

Outline

TREATMENT

When PPS is observed, tear the CA membrane, then the amniotic membrane (closest sac) surrounding the fetus and assist in its delivery.

Appropriate Health Care!!navigator!!

N/A

Client Education!!navigator!!

  • Knowledge regarding the normal appearance of a placenta at term.
  • With normal parturition—CA first to break = breaking water, but it is internal. When it tears (following pressure by fetal extremities), allantoic fluid is observed in a gush, but not the membrane at that time. The first membrane observed at the vulva should be the amnion—smooth and white, opaque, or pale pink.
  • Any reddish or roughened protruding membrane indicates a problem requiring immediate action (it is the CA).
  • This is a true emergency. Because of fetal hypoxia, insufficient time is available to seek outside assistance and still deliver a live foal.
  • Examine the placenta when freshly delivered, serves as an excellent teaching tool to educate clients regarding what is normal vs. abnormal.
  • If PPS is observed and the client cannot/will not tear the CA and assist in delivery, instruct the client to walk the mare until the veterinarian arrives.
    • May reduce further/full abdominal contractions and thus decrease further/full placental separation (still only partial usefulness) for a few minutes until your arrival

Medications ⬆ ⬇

Outline

MEDICATIONS

Drug(s) of Choice!!navigator!!

N/A

Contraindications/Possible Interactions!!navigator!!

Oxytocin is contraindicated before fetus has been delivered.

Follow-up ⬆ ⬇

Outline

FOLLOW-UP

Patient Monitoring!!navigator!!

  • Mares do well after delivery.
  • If alive when delivered, the neonate can suffer permanent damage due to O2 deprivation during delivery

Prevention/Avoidance!!navigator!!

  • No known method to prevent this condition.
  • Observe parturition for any mare with a history of PPS

Possible Complications!!navigator!!

  • Mare—none.
  • Fetus—this is a high-risk delivery; death caused by lack of oxygenation; dummy foal postpartum; prepare for neonatal intensive care.

Expected Course and Prognosis!!navigator!!

Delayed delivery results in hypoxia, and either a dummy foal and/or fetal death.

Miscellaneous ⬆ ⬇

Outline

MISCELLANEOUS

Associated Conditions!!navigator!!

N/A

Age-Related Factors!!navigator!!

N/A

Zoonotic Potential!!navigator!!

N/A

Pregnancy/Fertility/Breeding!!navigator!!

Only occurs at the end of gestation.

Synonyms!!navigator!!

  • Red bag.
  • Red bagging

Abbreviations!!navigator!!

  • CA = chorioallantoic/chorioallantois.
  • PPS = premature placental separation.
  • US = ultrasound, ultrasonography

Suggested Reading ⬆ ⬇

Bucca S, Fogarty U, Collins A, Small V. Assessment of feto-placental well-being in the mare from mid-gestation to term: transrectal and transabdominal ultrasonographic features. Theriogenology2005;64:542–557.

Cheong SH, Lawlis SM, Gilbert RO. Parturition augmentation in mares—efficacy and safety. Clin Theriogenol 2015;7(3):303.

Roberts SJ. Veterinary Obstetrics and Genital Diseases (Theriogenology), 3e. Woodstock, VT: SJ Roberts, 1986:251–252.

Author(s) ⬆

Author: Carla L. Carleton

Consulting Editor: Carla L. Carleton

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