Clinical studies on daily low dose oxytocin in mares at term.
Authors: Camillo F, Marmorini P, Romagnoli S, Cela M, Duchamp G, Palmer E
Journal: Equine veterinary journal
Summary
# Editorial Summary: Low-Dose Oxytocin for Predicting and Inducing Parturition in Mares Timing parturition in mares remains challenging for stud farm management, particularly when attempting to ensure veterinary supervision of delivery. Camillo and colleagues investigated whether a low-dose oxytocin protocol could serve a dual purpose: reliably inducing labour in ready mares whilst predicting which animals would not foal overnight if labour did not commence within two hours of treatment. Their study of 51 near-term Haflinger mares involved administering a single 2.5 iu intravenous injection of oxytocin in the early evening, with 41 mares receiving active treatment and 10 serving as controls, with labour response monitored over the following hours and overnight. Results showed that 95% of treated mares delivered normally within 120 minutes, with approximately two-thirds responding to the first injection, one-quarter to the second, and the remainder to a third treatment; critically, only 5% of treated mares foaled during the night regardless of injection response, compared to 70% of controls. The selectivity of this low-dose protocol—its ability to trigger labour only in truly ready mares whilst predicting negative responders—offers practical advantages for stud farm operations seeking to schedule supervision without forcing labour in immature fetuses, though application requires reliable pre-treatment assessment of fetal maturity via mammary calcium testing.
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Practical Takeaways
- •A single 2.5 IU IV oxytocin injection in evening can reliably induce parturition in mares confirmed ready by calcium strip test, delivering foals within 2 hours in most cases
- •If parturition does not occur within 2 hours of treatment, the mare is unlikely to foal overnight, allowing prediction of foaling timing for management planning
- •The low dose's selectivity for mature, ready foetuses minimizes risk of premature induction or complications from forcing immature pregnancies
Key Findings
- •Low-dose oxytocin (2.5 IU) induced delivery of normal foals within 120 minutes in 95% of treated mares (36/38)
- •First oxytocin injection induced foaling in 63% of responsive mares (24/38), second in 24% (9/38), and third in 8% (3/38)
- •Only 5% of treated mares foaled during night despite treatment versus 70% of control mares (7/10), indicating selective action on ready mares
- •Low-dose oxytocin appears to induce delivery only in mares with mature fetuses ready for parturition, serving as both induction method and readiness predictor