Manual of Equine Neonatal Medicine
Back to Table of Contents
Add to My Library
Comments
Print this article
Share:

Induction of Parturition

Author(s):
Madigan J.E.
In: Manual of Equine Neonatal Medicine - Revised by Madigan J.E.
Updated:
FEB 26, 2024
Languages:
Back to Table of Contents
Add to My Library
Print this article

Inappropriate and ill-timed inductions of parturition in mares can produce individual foal disasters. Remember, gestation length alone is not an indicator the mare is ready to foal. When performed carefully, and with adequate post foaling care, the procedure has recently been demonstrated to be relatively safe.1

Indications and Previous Uses of Induction of Parturition6

  • Allows daytime observation of foaling, permits scheduled veterinary or team supervision or teaching demonstration.
    Editorial Comment - I don't believe this is a good reason.
  • Previous history of complications at parturition such as premature placental separation.
  • Severe maternal illness, lameness, fracture, hydrops, etc.2

Determination of Readiness for Induction

Editorial comment

Foals mature in the very late stages of gestation and inducing delivery even a day too early can cause serious adverse consequences.

Methods 1-6

A. Oxytocin alone

  • A study evaluated the clinical applications and limitations of daily low-dose oxytocin injections for the induction of parturition in pregnant at term mares focusing on the efficacy of the treatment and on its possible negative effects on mare and foal. Mares in the study group were treated daily with 3.5 IU of oxytocin i.m. when mammary secretion showed a calcium concentration ≥ 200 ppm. Administration of oxytocin resulted in the delivery of a normal foal within 120 min in 68.9% of treated mares. No significant difference between treated and control mares was observed in the gestational length, duration of foaling, incidence of dystocia, failure of rupture of the allantochorion and the placental retention. Physical and behavioral characteristics were normal in foals of both groups. Study concluded that low doses of oxytocin in at term mares showed only moderate efficacy for inducing parturition.7 
  • Administration of 2.5 IU oxytocin, twice 2 hours apart in a previous study resulted in the delivery of a normal foal within 120 min in 95% of term mares. Authors concluded that a low dose induces delivery only in mares carrying a mature fetus and which are ready to foal8.
  • Low dose - 5 IU administered intravenously at 20 minute intervals to effect5
    • Interval to onset of parturition in term mares was 38-85 minutes.
  • Higher dose - 40-120 IU - may be associated with more complications.
  • Lower dose preferred method.
  • Earlier study suggests no difference with either 75 IU IM once, 15 IU IM q 15 minutes for 5 injections or 75 IU in 1 Liter saline @ 1 IU/min.9
    • Cervical dilation very important for normal outcome.9
    • Frequent premature placental separation 
      Editorial Comment - always break chorioallantois at start of labor.
    • For best chance of good outcome: 3/5 zones in Predict A foal test - udder development
Editorial comment

Recent review of oxytocin protocols suggest: Mares selected on clinical criteria receive 1 dose of 2.5 to 3.5 IU of oxytocin. Mares not responding to oxytocin are judged not yet ready for foaling and treatment is repeated the earliest after 24 h. parturition in mares12

B. Prostaglandin analogues

Not currently recommended

C. Corticosteroids

Dexamethasone: must be administered at high doses, 100 mg/day IM for 4 days - not recommended for non-emergency induction circumstances. Steroids administered to mares may cause acceleration of lung maturation in fetus.

Editorial comment

Can be tried in mares that cannot live to complete gestation.

  • Use in sheep10 (1-6 daily doses of 20 mg hydrocortisone sodium succinate) and women11 (0.1-0.2 mg/kg betamethasone. IM) suggest in horses we should dose steroids for minimum of 48 hours prior to birthing.
  • This dose may not induce parturition in mares.

Complications that have been Associated with Induction of Parturition in the Mare

  • Premature placental separation.
  • Delivery of premature foal that fails to adapt.
  • Dystocia - malposition of fetus.
  • Weakness in foals - maladjustment syndrome
  • Failure of passive transfer.
  • Myometrium hyperstimulation and colic in mare.

Post Parturition Management

  • Observe parameters post birth, time to stand and suck.
    Editorial Comment - If foal is not considered entirely normal, treat as a high risk foal and start antibiotics immediately and treat for maladjustment syndrome (Chapter 27 - Neonatal Maladjustment syndrome)
  • Routine post foaling care.
  • Provide follow-up with careful evaluation.
References
  1. Ley, W.B., Hoffman, J.L., Crisman, M.V., et al. Daytime foaling management of the mare 2: Induction of parturition. Equine Vet Sci 9:95-100, 1989
  2. Hillman, R.B. Induction of parturition in the mare. IN: Current Therapy in Theriogenology Diagnosis, Treatment and Prevention of Reproduction Diseases in Animals. D.A. Morrow (ED), WB Saunders, Co., Philadelphia, pp 753-755, 1980.
  3. Jeffcott, L.B., et al. A critical review of current methods for induction of parturition in the mare. Equine Vet J 9(4):208-215,1977.
  4. Hughes, J.: Personal Communication, 1990.
  5. Pashen, R.L. Low dose oxytocin can induce foaling at term. Equine Vet J 12(2):85-87, 1980.
  6. Leaden, D.P., et al. A comparison of agents for inducing parturition in the mare. Equine Vet J 16:256-259, 1982.
  7. Villani M, Romano G.: Induction of parturition with daily low- dose oxytocin injections in pregnant mares at term: clinical applications and limitations. Reprod Domest Anim. 2008. Aug;43(4):481
  8. Camillo F, Marmorini P, Romagnoli S, Cela M, Duchamp G, Palmer E.: Clinical studies on daily low dose oxytocin in mares at term Equine Vet J. 2000. Jul;32 (4):307-10.
  9. Macpherson, ML, Chaffin, MK, Carrol, GL, et al.: Three methods for oxytocin-induced parturition: Effects on the neonatal foal. Proceed. Am Assoc Equine Pract 42:150-151,1996.
  10. DeLemos, R. Acceleration of pulmonary surfactant in the fetal lamb by administration of corticosteroids. Am Rev Resp Dis 102:459-461, 1970.
  11. Liggins, G.C., Howie, R.N. A controlled trial of antepartum glucocorticoid treatment for prevention of the respiratory distress syndrome in premature infants. Pediatrics 50:515-525, 1972.
  12. Nagel, C. Aurich C. Induction of parturition in horses – from physiological pathways to clinical applications. Domestic Animal Endocrinology 78 (2022) 106670
Back to Table of Contents
Add to My Library
Print this article

Ask the author

0 comments
Submit

How to reference this publication (Harvard system)?

Madigan, J. E. (2024) “Induction of Parturition”, Manual of Equine Neonatal Medicine - Revised. Available at: https://www.ivis.org/library/manual-of-equine-neonatal-medicine-revised/induction-of-parturition (Accessed: 12 September 2024).

Author(s)

  • John Madigan

    Madigan J.E.

    Professor of Medicine and Epidemiology
    MS DVM Dipl. ACVIM ACAW
    Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California
    Read more about this author

Copyright Statement

© All text and images in this publication are copyright protected and cannot be reproduced or copied in any way.

Readers also viewed these publications

Buy this book

The eagerly awaited REVISED 4th edition is now available for download in ePDF format. For those who prefer the convenience of the traditional pocket-sized Manual, it's also accessible in that familiar form, perfect for slipping into your glove box or coverall pocket. Now, you can have it with you in whichever format suits your needs best.

For more details and to get your copy, visit https://www.equineneonatalmanual.com/.

Manual of Equine Neonatal Medicine
Back To Top