Effect of butorphanol on thermal nociceptive threshold in healthy pony foals.
Authors: McGowan K T, Elfenbein J R, Robertson S A, Sanchez L C
Journal: Equine veterinary journal
Summary
# Editorial Summary: Butorphanol Analgesia in Pony Foals Effective pain relief in foals remains challenging due to limited evidence on opioid efficacy in this age group, prompting researchers to assess whether butorphanol—a commonly administered analgesic—could reliably raise pain thresholds across different developmental stages. The study compared two intravenous butorphanol doses (0.05 and 0.1 mg/kg bodyweight) against saline placebo in seven neonatal (1–2 weeks old) and eleven older pony foals (4–8 weeks old) using a randomised crossover design, measuring thermal nociceptive threshold alongside behavioural and skin temperature responses. Only the higher dose of 0.1 mg/kg produced a statistically significant increase in thermal pain threshold in both age groups without triggering concerning behavioural changes, whilst the lower 0.05 mg/kg dose proved ineffective. These findings provide the first objective evidence that butorphanol can suppress somatic pain perception in foals, offering clinicians confidence when selecting dosing protocols for managing conditions such as fractures, surgical trauma, or septic arthritis during the critical early weeks of life. Further investigation into duration of effect and visceral pain management would strengthen guidance for practitioners treating painful foal conditions across different clinical scenarios.
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Practical Takeaways
- •Butorphanol at 0.1 mg/kg IV is an effective analgesic for somatic pain in foals from 1-8 weeks of age and can be used for pain management in neonatal and nursing care situations
- •The lower dose of 0.05 mg/kg is insufficient for analgesia in foals; practitioners should use at least 0.1 mg/kg to achieve measurable antinociceptive effects
- •This is the first objective evidence supporting opioid efficacy in foals, filling a significant knowledge gap in equine neonatal pain management protocols
Key Findings
- •Butorphanol at 0.1 mg/kg bwt significantly increased thermal nociceptive threshold in both neonatal (1-2 weeks) and older (4-8 weeks) pony foals compared to saline control
- •Butorphanol at 0.05 mg/kg bwt did not produce significant antinociceptive effects in either age group
- •No significant adverse behavioural effects were observed at the effective analgesic dose of 0.1 mg/kg bwt
- •Thermal nociceptive threshold response to butorphanol was consistent between neonatal and older foals, suggesting dose-dependent efficacy across early foal ages