Hemodynamic effects in dogs anesthetized with the combination tiletamine-zolazepam-ketamine-xylazine

This was a prospective, experimental study, that evaluated the hemodynamic effects in dogs administered the combination tiletamine-zolazepam-ketamine-xylazine (TKX). Six healthy, adult dogs, with an average weight of 13.9 ± 1.3 kg, were anesthetized with propofol and sevoflurane for placement of an arterial and a thermodilution catheter. After instrumentation, sevoflurane was discontinued and approximately 60 min were allowed before baseline data was recorded. Dogs were then administered TKX at a dosage of 0.032 mL/kg, corresponding to 1.6 mg/kg of tiletamine, 1.6 mg/kg of zolazepam, 2.56 mg/kg of ketamine and 0.64 mg/kg of xylazine. Assessments were repeated at 15, 30 and 45 min after TKX administration (T15, T30 and T45). Comparisons between T15-T45 and the baseline were performed by one-way ANOVA followed by a Dunnett's test or a Friedman's test followed by a Dunn's test (p < 0.05). Administration of TKX decreased heart rate (27-43%), cardiac index (48-55%), stroke index (21-28%), oxygen delivery index (49-56%) and oxygen consumption index (41-44%), and increased mean arterial pressure (26-43%), systemic vascular resistance index (211-234%) and oxygen extraction ratio (17-28%). Respiratory rate decreased by as much as 41% without significantly affecting blood gases. It was concluded that TKX administration resulted in cardiovascular depression in dogs, characterized by decreased heart rate, cardiac index and oxygen delivery index. Despite respiratory rate decreased, blood gases were unchanged. These cardiorespiratory effects were well tolerated by healthy dogs. Nonetheless, the findings of this study should not be extrapolated to dogs with compromised health conditions.