Serum biochemical indicators of hepatobiliary function in dogs following prolonged anaesthesia with sevoflurane or isoflurane.

OBJECTIVE To investigate the changes in serum enzymes considered as biochemical indicators of hepatobiliary function in dogs following 5 hours of anaesthesia with isoflurane (ISO) or sevoflurane (SEVO). STUDY DESIGN Experimental randomized crossover study, with intervals of at least 15 days between successive treatments. ANIMALS Eight healthy adult mongrel dogs, four male, four female, weight 13.6-21.6 kg. METHODS Treatments consisted of anaesthesia with ISO or SEVO at 1 or 1.5 minimum alveolar concentration (MAC) delivered in oxygen. MAC was taken as 1.39% for ISO and 2.36% for SEVO. Anaesthesia was induced by mask then, after endotracheal intubation, maintained according to the treatment protocol using a small animal circle system. Cardiopulmonary monitoring was carried out. Venous blood samples, obtained by needle puncture, were taken at 24 hours and 2, 7 and 14 days post anaesthesia. Serum concentrations of total protein, aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase, (LDH), alkaline phosphatase (ALP), gamma-glutamyltransferese and total bilirubin were measured. Changes with time and with treatment were compared by Friedman analysis, Wilcoxon Signed test and Kruskal-Wallis test as relevant. p- value < 0.05 was considered significant. RESULTS Compared to base-line values, at 24 hours post-anaesthesia there were significant increases in AST, ALT, ALP and LDH following one or more of the treatments, but by 2 days residual changes were not significant. At 24 hours, AST for treatment 1.5 MAC ISO was higher than 1 MAC ISO (p < 0.002), and LDH higher for 1.5 MAC SEVO than 1 MAC SEVO. CONCLUSION AND CLINICAL RELEVANCE Both ISO and SEVO, at concentrations used for clinical anaesthesia, produce transient moderate effects on some hepatobiliary enzyme concentrations in dogs.