The Effectiveness of Liposome-Encapsulated Bupivacaine Compared to Standard Bupivacaine for Anesthesia of the Maxilla in Dogs.

Medical and surgical procedures involving the canine maxilla can be painful both during and for several hours post-procedure. The length of this pain may exceed the predicted duration of standard bupivacaine or lidocaine. The goal of this study was to determine the duration and efficacy of sensory blockade of the maxilla produced by liposome-encapsulated bupivacaine (LB), compared to standard bupivacaine (B) or saline (0.9% NaCl) (S), when administered as a modified maxillary nerve block in dogs. Eight maxillae were studied bilaterally from 4 healthy dogs of the same breed and similar age. This prospective, randomized, crossover, blinded study evaluated a modified maxillary nerve block using 1.3% LB at 0.1 mL/kg, 0.5% B, or S at an equivalent volume. An electronic von Frey aesthesiometer (VFA) was used to evaluate mechanical nociceptive thresholds at 4 locations on each hemimaxilla at baseline and at specific intervals up to 72-h post-treatment. Both B and LB treatments resulted in significantly higher VFA thresholds when compared to S. Dogs that received B had VFA thresholds significantly higher than S for 5 to 6 h. Dogs that received LB had thresholds significantly higher than S for 6 to 12 h depending on the site of measurement. No complications were observed. Maxillary nerve block with B provided up to 6 h, and LB 12 h, of sensory blockade depending on the site tested.