Investigation of some pathophysiological effects of prolonged hypocalcaemia in sheep induced by infusing Na2EDTA solution for 4 hours daily on three consecutive days.

Hypocalcaemia was induced in a group of five aged Merino ewes (with low erythrocyte potassium status) by the intravenous infusion of 4.7% Na2EDTA solution for 4 h daily on 3 consecutive days. A similar control group was infused with 5.0% dextrose solution (10 ml/h) for the same period. Blood samples were taken immediately before infusion each day, hourly for 7 h, then at 08:00 each morning for a further 5 d. Studies were made on the changes in plasma (P) Ca, PNa, PK, PMg, PProtein (PProt), P inorganic phosphorus (PiP), erythrocyte (E) Na, EK, EMg, PCVs, and mean corpuscular cell volumes (MCV). Significant decreases occurred in PiP concentrations but these were only temporary, which suggests that PiP is unlikely to be involved in the complications of prolonged hypocalcaemia. Significant prolonged decreases in PNa, PK and EK and significant prolonged increases in PCVs suggested that fluid replacement therapy supplemented with Na and K may be worthy of further study in the treatment of ruminants affected by apparent biochemical or physiological complications to prolonged hypocalcaemia.