Anaemia and Hypoproteinaemia in Pregnant Sheep during Anaesthesia

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.