Purpose: To evaluate hemodynamics and bispectral index (BIS) in bitches anesthetized with ketamine and midazolam in combination with dexmedetomidine or medetomidine and submitted to ovariohysterectomy.
Methods: Twenty bitches pretreated with levomedetomidine and buprenorphine were anesthetized with 5 mg*kg(-1) ketamine and 0.2 mg*kg(-1) midazolam i.v. Continuous infusion of 0.4 mg*kg(-1)*h(-1) midazolam and 20 mg*kg(-1)*h(-1) ketamine was initiated in combination with DEX (n=10): 20 microg*kg(-1)*h(-1) dexmedetomidine or MED (n=10): 30 microg*kg(-1)*h(-1) medetomidine over 30 minutes. A pharmacokinetic study provided dexmedetomidine plasma concentration, set to be 3.0 ng*mL(-1).
Results: BIS decreased in both groups (P<0.05), but it was lower in DEX (P<0.05) as compared to MED. No differences were found in hemodynamic parameters (heart rate, systolic, diastolic and mean arterial pressure) between groups (P>0.05), but heart rate decreased in both groups, as compared to control values (P<0.05). Respiratory rate decreased (P<0.05) and expired end tidal CO(2) increased progressively (P<0.05) and similarly in both groups. Anesthetic recovery period was similar between groups (P<0.05) with no adverse effects.
Conclusion: Continuous administration of dexmedetomidine with calculated plasma concentration equal to 3 ng.mL-1 in combination with midazolam and ketamine provides suitable anesthesia for spay surgery in bitches, hemodynamic stability and calm awakening with no adverse effects.