Transdermal Application of Anesthetic Preparations Is Effective in Increasing Mechanical Nociceptive Threshold at Perineural Injection Sites in Horses

Perineural anaesthesia is an essential part of lameness investigation in horses. Painful reactions to injections imply a high risk of accidents for veterinarians. To evaluate the efficacy of two topical anaesthetic creams on desensitization of the skin at two perineural injection sites and to evaluate the effects these formulations may have on pain perception distally to the application sites. Randomized, blind, prospective study. 14 healthy horses were randomly divided in two groups of 7 horses each, one treated with EMLA and one with PLIAGLIS preparations. The mechanical nociceptive threshold (MNT) was recorded via pressure algometer at the baseline and one hour after application (T1) on palmar and palmar digital nerve blocks sites. Skin sensation was also assessed on the distal limb, recording MNT on the coronary band and on both bulbs of the heels. Data were compared with a 3-way ANOVA statistical analyses. No significant difference was encountered in the MNT values between baseline records and records at T1 at the control sites. A significant difference of MNT values was detected between the two time points in the treated limbs. The significant sources of variation in our study were the time and the presence of anaesthetic cream. The type of treatment did not determine any differences. Furthermore, no significant difference of MNT values at sites distal to treatment was recorded between the two time points, both in the treated limb and control limbs. Both formulations are effective to obtain superficial skin desensitization