Physiologic and blood gas effects of xylazine-ketamine versus xylazine-tiletamine-zolazepam immobilization of white-tailed deer before and after oxygen supplementation: a preliminary study.

Objective: To compare oxygenation and ventilation in white-tailed deer (Odocoileus virginianus) anesthetized with two treatments with and without oxygen supplementation.
Study Design: Randomized, blinded, crossover study.
Animals: A total of eight healthy adult white-tailed deer weighing 49-62 kg.
Methods: Each deer was anesthetized twice intramuscularly: 1) treatment XK, xylazine (2 mg kg ^-1 ) and ketamine (6 mg kg ^-1 ) and 2) treatment XTZ, xylazine (2 mg kg ^-1 ) and tiletamine-zolazepam (4 mg kg ^-1 ). With the deer in sternal position, arterial and venous blood was collected before and at 30 minutes during administration of oxygen at 1 L minute ^-1 through a face mask. PaO ₂ and heart rate (HR) were compared using two-way repeated measures anova. pH, PaCO ₂ and lactate concentration were analyzed using mixed-effects linear models, p < 0.05.
Results: When breathing air, PaO ₂ was < 80 mmHg (10.7 kPa) in six and seven deer with XK and XTZ, respectively, and of these, PaO ₂ was < 60 mmHg (8.0 kPa) in three and five deer, respectively. With oxygen supplementation, PaO ₂ increased to 128 ± 4 and 140 ± 5 mmHg (17.1 ± 0.5 and 18.7 ± 0.7 kPa), mean ± standard error, with XK and XTZ, respectively (p < 0.001). PaO ₂ was not significantly different between treatments at either time point. HR decreased during oxygen supplementation in both treatments (p < 0.001). Lactate was significantly lower (p = 0.047) with XTZ than with XK (2.2 ± 0.6 versus 3.5 ± 0.6 mmol L ^-1 ) and decreased (p < 0.001) with oxygen supplementation (4.1 ± 0.6 versus 1.6 ± 0.6 mmol L ^-1 ). PaCO ₂ increased in XTZ during oxygen breathing.
Conclusions and Clinical Relevance: Treatments XK and XTZ resulted in hypoxemia, which responded to oxygen supplementation. Both treatments are suitable for immobilization of white-tailed deer under the study circumstances.
(Copyright © 2021 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.)