This study compares the duration of epidural anesthesia using 2% lidocaine (Lido) with versus without a thermo-responsive hydrogel (TRH) in dogs.
Methods: Six Beagles (11.0 ± 0.7 kg) were sedated with intravenous medetomidine (40 µg kg-1) three times, separated by 2-weeks, for epidural injections of TRH, Lido, and Lido-TRH in random order. Heart rate, blood pressure, and oxygen saturation were monitored. In sternal recumbency, a Tuohy needle (24 G) was inserted into the sacrococcygeal epidural space, whose correct insertion site was verified with a C-arm. Treatment solution (0.2 mL kg-1) was injected epidurally, and then atipamezole (200 µg kg-1) was administered intravenously. In TRH treatment, hypersensitivity, ambulation, anal tone, and tail movement were monitored. In all treatments, a skin-pinching test using mosquito hemostatic forceps was blindly performed at 5 cm cranial to the injection site, at the injection site, and 5 cm caudal to the injection site, before sedation (baseline) and every 10 minutes after epidural injection until the sensory function returned to baseline. The TRH effect on block duration was compared using a linear mixed model.
