Evaluation of cardiorespiratory and biochemical effects of ketamine-propofol and guaifenesin-ketamine-xylazine anesthesia in donkeys (Equus asinus).

Objectives: To evaluate the cardiorespiratory and biochemical effects of ketamine-propofol (KP) or guaifenesin-ketamine-xylazine (GKX) anesthesia in donkeys.

Study Design: Prospective crossover trial.

Animals: Eight healthy, standard donkeys, aged 10 ± 5 years and weighing 153 ± 23 kg.

Methods: Donkeys were premedicated with 1.0 mg kg(-1) of xylazine (IV) in both treatments. Eight donkeys were administered ketamine (1.5 mg kg(-1)) and propofol (0.5 mg kg(-1) for induction, and anesthesia was maintained by constant rate infusion (CRI) of ketamine (0.05 mg kg(-1) minute(-1)) and propofol (0.15 mg kg(-1) minute(-1)) in the KP treatment. After 10 days, diazepam (0.05 mg kg(-1)) and ketamine (2.2 mg kg(-1)) were administered for induction, and anesthesia was maintained by a CRI (2.0 mL kg(-1) hour(-1)) of ketamine (2.0 mg mL(-1), xylazine (0.5 mg mL(-1)) and guaifenesin (50 mg mL(-1)) solution. Quality of anesthesia was assessed along with cardiorespiratory and biochemical measurements.

Results: Anesthetic induction took longer in GKX than in KP. The induction was considered good in 7/8 with KP and in 6/8 in GKX. Anesthetic recovery was classified as good in 7/8 animals in both treatments. Xylazine administration decreased heart rate (HR) in both treatments, but in KP the HR increased and was higher than GKX throughout the anesthetic period. Respiratory rate was higher in GKX than in KP. PaO(2) decreased significantly in both groups during the anesthetic period. Glucose concentrations [GLU] increased and rectal temperature and PCV decreased in both treatments. Arterial lactate [LAC] increased at recovery compared with all time points in KP. [GLU] and calcium were higher in GKX than in KP at recovery.

Conclusion And Clinical Relevance: These protocols induced significant hypoxemia but no other cardiorespiratory or metabolic changes. These protocols could be used to maintain anesthesia in donkeys, however, they were not tested in animals undergoing surgery.