Dexmedetomidine as a Preanesthetic Prior to Propofol- or Thiopental-Isoflurane Anesthesia in Dogs
Orion Corporation Orion Pharma, Clinical Research and Development, Turku, Finland; 1Professor Emeritus, Cornell University, Ithaca, NY, USA
Background
Dexmedetomidine, the d-enantiomer of medetomidine, is the most specific and selective alpha-2 adrenoceptor agonist approved for veterinarians.
Aims
To evaluate the clinical efficacy and safety of dexmedetomidine preanesthesia for elective canine veterinary procedures.
Methods
Ninety-six clinically healthy dogs were studied in a double-blind placebo-controlled randomized clinical study with 6 groups of 16 dogs: 0 (placebo), 125 or 375 mcg/m2 of dexmedetomidine (D) was administered intramuscularly 20 minutes prior to intravenous propofol or thiopental induction and isoflurane maintenance. Assessments included pre-induction sedation score (SED; 0-10), dose of induction drug (IND), isoflurane concentration (ISO), number of animals observed with clinically significant (score >2) postoperative pain (PAIN; 0-9). Cardiorespiratory data were collected before treatment, during the procedure and for 180 minutes post-procedure and adverse events (AE) were recorded. Data were analyzed by ANOVA and Chi-square tests.
Results
|
|
Propofol |
Thiopental |
|
|
D0 |
D125 |
D375 |
D0 |
D125 |
D375 |
|
SED, median |
0b |
3ab |
5a |
0b |
3ab |
5a |
|
IND, mg/kg |
5.4±1.8a |
3.1±1.4ab |
2.7±1.6b |
17.5±2.7a |
12.3±4.2b |
7.4±3.9c |
|
ISO, % |
2.9±0.8a |
1.8±0.6b |
1.1±0.3c |
2.4±0.6a |
1.6±0.7b |
1.1±0.3b |
|
PAIN, n |
5a |
2ab |
0b |
6a |
0b |
0b |
|
AE, n |
6 |
6 |
5 |
4 |
6 |
5 |
a,b,c D groups differ (P < 0.05) within propofol and thiopental.
D125 or D375 resulted in dose-dependent preoperative sedation, 30-58% less propofol or thiopental required for induction, less ISO for anesthetic maintenance, and less PAIN than D0. AE was similar between groups and primarily included vomiting (n=19) or transitory arrhythmia and bradycardia (n=6).
Conclusion
Dexmedetomidine appears to be an effective and safe preanesthetic for elective canine procedures.