|Abstract or Summary
- The effects of alfaxalone (A-HPCD)
- The effects of alfaxalone (A-HPCD), propofol (P), ketamine-diazepam (KD) and tiletamine-zolazepam (TZ) administered IV in dogs on cardiovascular and respiratory systems, acid-base balance and electrolytes have been reported in the literature, but a study that compares IV TZ to the other induction protocols (IP) is needed. Six dogs enrolled in a randomized-crossover study were anesthetized with sevoflurane and instrumented. After at least 30 minutes post-recovery, baseline values for cardiovascular and respiratory parameters were determined, cardiac output (CO) measured via thermodilution, and arterial (Art) and mixed venous (MV) blood samples collected. Anesthesia was induced with A-HPCD (4 mg kg), P (6 mg kg), KD (7 and 0.3 mg kg, respectively), or TZ (5 mg kg) administered IV in quarter increments to effect, and maintained with isoflurane (Et[subscript Iso] 1.14 ± 0.32%) for 60 minutes. Immediately post-induction (PI) and at 10, 20, 40, and 60 minutes all measurements were repeated and blood sampled. Derived hemodynamic parameters were calculated. Cardiorespiratory and acid-base parameters compared with RM-ANOVA and a post-hoc t-test were considered significant when p < 0.05. The parameter most affected by protocol was heart rate (HR), with TZ producing the highest HR PI and at 40 and 60 minutes. Oxygen delivery (DO₂) was best maintained by TZ in the first 20 min, while A-HPCD maintained the highest DO₂ at 60 minutes. No significant differences for CO, cardiac index, mean arterial pressure, and systemic vascular resistance were found among IP. Although still within normal limits, mean MV pH, Art and MV potassium were similarly increased with TZ and KD compared to P and A-HPCD. Although statistical significance was found for EtCO₂, pH, lactate, and serum potassium, values stayed in the normal clinical range. TZ produced comparable respiratory changes to KD. Intravenous induction of general anesthesia with TZ maintained on isoflurane is a safe alternative to A-HPCD, KD, and P in healthy dogs and it is recommended for short anesthetic procedures.