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

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.

Blinded, randomized crossover trial.

Thirty healthy adult horses [16 ± 3.9 years old (mean ± standard deviation), weighing 594 ± 63 kilograms (kg)].

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.

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.

Icing of the skin did not significantly improve compliance to infraorbital nerve block placement in sedated horses.