Efficacy of epidural lidocaine combined with tramadol or neostigmine on perineal analgesia in the horse.

REASONS FOR PERFORMING STUDY: Short duration of analgesia is among the limitations of a single epidural injection with lidocaine in horses.

OBJECTIVES

To evaluate the effectiveness and safety of epidural lidocaine in combination with either tramadol or neostigmine for perineal analgesia in horses.

METHODS

Epidural catheters were placed in 6 saddle horses that then were given 3 treatments: 2% lidocaine (0.2 mg/kg bwt) alone, 2% lidocaine (0.2 mg/kg bwt) plus tramadol (0.5 mg/kg bwt), and 2% lidocaine (0.2 mg/kg bwt) plus neostigmine (1.0 μg/kg bwt). The order of treatments was randomised. Haemodynamic variables, respiratory rate, rectal temperature, analgesia, motor block and behaviour scores were compared among the 3 treatments. These parameters were determined before drug administration (baseline), at 5, 10, 15, 30, 45, 60, 75 and 90 min, and every 30 min thereafter until loss of analgesia.

RESULTS

Duration of analgesia was longer with lidocaine plus tramadol (210 ± 12 min) compared with lidocaine plus neostigmine (150 ± 35 min) or lidocaine alone (70 ± 12 min; P<0.05). All treatments produced mild or moderate motor block without behavioural changes. Other adverse effects were not observed in any of the horses.

CONCLUSION AND POTENTIAL RELEVANCE: Further studies are required to demonstrate whether tramadol or neostigmine have a role in the management of post operative pain when coadministered with lidocaine.