A quantitative study on recovery from acute haemorrhage in adult laboratory rats. I. Blood morphology.

We evaluated changes in blood morphology for detecting acute blood loss in laboratory rats. Haematologic indices which are normally used in investigating drug effects on rat blood morphology were examined. Sublethal acute blood loss (25 ml per kg body weight) modified rat blood morphology in a few minutes; the blood picture was normal within two weeks. Blood drawing (usually up to 10 ml per kg b.w.) can modify rat blood morphology within one week. Erythrocyte counts, haemoglobin concentration and haematocrit decreased earliest, reticulocyte counts were changed longest. Comparing our results and literature data the recovery of blood morphology from acute haemorrhage seems to be more rapid in rats than in men.