The effects of handling procedures, breed differences and treatment with lithium and dexamethasone on some blood parameters in sheep

Abstract

Fifteen aged Merino and 15 aged Border Leicester ewes each divided into 3 groups of 5 for infusion with lithium chloride, lithium chloride plus dexamethasone and normal saline, and then subjected to 3 jugular venous blood samplings, 1 h apart, in a 3 × 3 × 2 experimental design involving times × treatments × breeds. The blood samples were examined for packed cell volumes, plasma and erythrocyte sodium and potassium concentrations, and plasma calcium concentrations. There were significant changes in packed cell volumes (PCV) 39 v. 30%; 39 v. 31%), plasma sodium concentrations (151 v. 149 mmol l −1; 151 v. 148 mmol l −1) and plasma potassium concentrations (5.3 v. 4.6 mmol l −1; 5.3 v. 4.7 mmol l −1) between Times 0 and 1 and between Times 0 and 2, respectively. There were no significant changes in plasma calcium or erythrocyte sodium or potassium concentrations associated with times. The evidence suggests that the times-effects were caused by different methods of handling the sheep immediately prior to each blood sampling, and this is discussed. The fall in PCV was greater than that recorded by other authors. There were highly significant ( P < 0.01) breed differences in PCV (36 v. 31%), plasma calcium concentrations (2.0 v. 2.2 mmol l −1) and erythrocyte potassium concentrations (10.1 v. 15.0 mmol l −1) for Merino and Border Leicester ewes, respectively. There were no significant breed differences in plasma potassium or erythrocyte sodium concentrations. The mean plasma potassium concentration of 5.08 mmol l −1 for the lithium-treated sheep was significantly higher than the means of 4.67 and 4.77 mmol l −1 for lithium plus dexamethasone and saline-treated groups, respectively. There was no significant difference between the latter two means, and there were no significant treatment effects for any of the other blood constituents.