Epidural analgesia using dexmedetomidine and its combinations with local anaesthetics for elective ovariohysterectomy in dogs

Twenty healthy client owned adult dogs presented for elective ovariohysterectomy were randomly divided into four equal groups (A, B, C and D). All the animals were premedicated with atropine 0.04 mg/kg b.wt, i.m and after 5 min midazolam 0.7 mg/kg b.wt, i.v. After 10 min of premedication, in group A dexmedetomidine 7 μg/kg body weight and in groups B, C and D, in addition to dexmedetomidine, lidocaine 4.4 mg/kg body weight, bupivacaine 2 mg/kg body weight and ropivacaine 2 mg/kg body weight, respectively were administered at the lumbosacral epidural space. Anesthesia was maintained with propofol (1%) as and when needed. Muscle relaxation was moderate in group A and profound in the other three groups. Complete analgesia at different regions was observed in groups B, C and D and mild to moderate analgesia was observed in group A. Onset and duration of analgesia was fastest in group C. Recovery time was longer in group C and shorter in group A. An initial increase in HR was followed by a significant (P<0.05) decrease from 60 min onwards in group A, however, HR remained marginally (P>0.05) above the baseline in groups B and C and marginally (P>0.05) below the baseline in group D. RR did not change significantly in any group. RT decreased significantly (P<0.05) in all the groups. It was concluded that epidural dexmedetomidine in combination with local anaesthetics causes minor changes in clinicophysiological parameters, provides better extent and depth of intra-operative analgesia than local anaesthetics alone and therefore, can be considered for elective ovariohysterectomy in dogs.