Investigating the effect of surface cryotherapy on equine patient compliance to infraorbital nerve block placement

OBJECTIVE: To investigate the effect of applying ice to the skin overlying the infraorbital canal on the compliance of healthy adult horses to infraorbital nerve block placement during standing sedation. STUDY DESIGN: Blinded, randomized crossover trial. ANIMALS: Thirty healthy adult horses [16 ± 3.9 years old (mean ± standard deviation), weighing 594 ± 63 kilograms (kg)]. METHODS: Each horse acted as its own control with a minimum of 7 days between treatments. Horses were sedated using detomidine hydrochloride, and sedation level was evaluated using a published simple descriptive scale. Horses were randomly assigned to 5 minutes of icing (ICE) or no icing (N-ICE) before block placement. An infraorbital nerve block was performed using 5 mL of mepivacaine 2%. Block efficacy was tested using a 25-gauge needle prick. Nerve blocks were filmed and reviewed by two investigators blinded to treatment, and horse compliance was assessed using a visual analogue scale (VAS) from 0 to 10. Investigator scores were added together for a total score out of 20. VAS scores were evaluated using a paired t-test. Any adverse effects were documented. RESULTS: There was no significant difference in compliance scores between groups (P = 0.179). VAS score for the ICE and N-ICE groups was 13.74 ± 6.2 and 11.81 ± 6.9, respectively. In the ICE group, 24/30 blocks were considered successful, versus 18/30 in the N-ICE group. No adverse effects were noted associated with icing. CONCLUSIONS AND CLINICAL RELEVANCE: Icing of the skin did not significantly improve compliance to infraorbital nerve block placement in sedated horses.