Use of arterial blood gas analysis as a superior method for evaluating respiratory function in pet rabbits (Oryctolagus cuniculus).

A retrospective study compared invasive (arterial blood gas analysis) and non-invasive (capnography and pulse oximetry) methods of monitoring respiratory function in conscious rabbits. Arterial samples from 50 healthy dwarf lop rabbits, presenting for routine surgical neutering, were analysed on a point-of-care blood gas analysis machine. Reference intervals were obtained for pH (7.35-7.54), PaCO2 (mm Hg) (25.29-40.37), PaO2 (mm Hg) (50.3-98.2), base excess (mmol/l) (6.7-6.5), HCO3 (mmol/l) (17.96-29.41), TCO2 (mmol/l) (18.9-30.5). SaO2 (per cent) (88.8-98.0), Na (mmol/l) (137.6-145.2), K (mmol/l) (3.28-4.87), iCal (mmol/l) (1.64-1.94), glucose (mmol/l) (6.23-10.53), haematocrit (per cent) (23.3-40.2) and haemoglobin (mg/dl) (7.91-13.63). Pulse oximetry (SPO2) and capnography (ETCO2) readings were taken concurrently. There was no statistically significant relationship between SPO2 and SaO2 with a mean difference between SPO2 and SaO2 of 8.22 per cent. There was a statistically significant relationship between ETCO2 vs PaCO2, but a wide range of ETCO2 values were observed for a given PaCO2. The mean difference between these was 16.16 mm Hg. The study has provided reference intervals for arterial blood gas analysis in rabbits and demonstrated that capnography and pulse oximetry readings should not be relied upon in conscious rabbits as a guide to ventilation and oxygenation.