The aim of this study was to document the packed cell volume (PCV), haemoglobin concentration and total protein concentration of maternal blood before, during and after anaesthesia. Six singleton Merino-cross pregnant ewes at 116-117 days of gestation were premedicated with intramuscular acepromazine (0.02 mg/kg) and buprenorphine (0.01 mg/kg), and anaesthesia was induced with intravenous midazolam and ketamine. Anaesthesia was maintained with isoflurane in 100% oxygen. Serial blood samples were collected the day before anaesthesia (baseline), immediately prior to induction of anaesthesia (pre-op), at the end of the procedure (intra-op) and the following day (post-op). There was a significant change in the PCV during the study (p = 0.003) with an initial decrease of 12.5% from the baseline (0.36 (0.36-0.4) to 0.315 (0.29-0.34), p = 0.044), a further intraoperative decrease of 41.7% from the baseline (0.21 (0.195-0.245), p = 0.002) and an increase the day afterwards (0.3 (0.285-0.35), p > 0.99 compared with baseline). The haemoglobin concentration also changed (p < 0.0001) (baseline: 114 (111.8-123); pre-op: 97 (77.25-104.5), 14.9% decrease, p = 0.022; intra-op: 70 (61.5-83.25), 38.5% decrease, p = 0.0009; post-op: 101.5 (96.25-114) g/L, p > 0.99). Likewise the change in total protein during the study was significant (p = 0.0003) and decreased from the baseline [70 (67.25-70.75) g/L] prior to anaesthesia (61 (58.25-64.5) g/L, 12.9% decrease, p = 0.0437) and further during anaesthesia (55.5 (53.75-63.25) g/L, 20.7% decrease, p = 0.0021) with an increase [63 (61.25-67) g/L, p > 0.99] on the first post-op day. In conclusion, intraoperative anaemia and hypoproteinaemia occurred in this study. These alterations are attributed to a combination of the side effects of acepromazine and haemodilution.
Keywords: anaemia; anaesthesia; pregnant sheep.