Cardiorespiratory and antinociceptive effects of two different doses of lidocaine administered to horses during a constant intravenous infusion of xylazine and ketamine.
Authors: Nóbrega Neto Pedro I, Luna Stelio P L, Queiroz-Williams Patricia, Mama Khursheed R, Steffey Eugene P, Carregaro Adriano B
Journal: BMC veterinary research
Summary
# Editorial Summary Xylazine-ketamine anaesthesia is widely used in equine practice, but managing intraoperative pain remains challenging; this investigation examined whether adding lidocaine infusions could enhance antinociception during maintenance and whether dose-dependent effects existed. Six mares underwent three separate anaesthetic protocols combining xylazine and ketamine maintenance with either high-dose lidocaine (5 mg/kg loading dose followed by 100 μg/kg/min infusion), low-dose lidocaine (2.5 mg/kg loading followed by 50 μg/kg/min infusion), or saline control, with pain responses measured via electrical stimulation threshold and bispectral index monitoring over a 75-minute period. Both lidocaine regimens significantly improved antinociception compared to placebo, with the higher dose providing superior pain suppression, whilst cardiorespiratory variables and depth-of-anaesthesia indices were measured to assess safety margins. For equine practitioners, these findings suggest that lidocaine infusions administered during routine xylazine-ketamine procedures can meaningfully reduce pain perception without compromising haemodynamic stability, potentially improving intraoperative conditions and post-operative recovery, though dose optimisation remains important for balancing analgesia against systemic effects.
Read the full abstract on PubMed
Practical Takeaways
- •Lidocaine infusions may enhance pain control during general anesthesia in horses when combined with xylazine and ketamine protocols
- •Two dosing regimens were tested; higher dose (100 µg/kg/min) and lower dose (50 µg/kg/min) effects should inform clinical decision-making for intra-operative analgesia
- •Monitoring BIS and cardiorespiratory parameters helps optimize anesthetic depth and safety when using multi-drug protocols with lidocaine
Key Findings
- •Two different doses of lidocaine CRI (100 µg/kg/min and 50 µg/kg/min) were compared for antinociceptive effects during xylazine-ketamine anesthesia in horses
- •Antinociception was measured by response to electrical stimulation and correlated with cardiorespiratory variables, BIS, and plasma lidocaine concentrations
- •Study evaluated whether lidocaine supplementation provides additional analgesic benefits during maintenance of equine general anesthesia