Haematology of the racing Thoroughbred in Australia 1: reference values and the effect of excitement.

Eight hundred and sixteen blood samples were collected from horses at Sydney race tracks, 1 to 3 h before racing, and subjected to haematological analysis. Haemograms were also performed on 65 blood samples taken from horses at rest in their stalls. These were used as reference values of prerace and resting haemograms, respectively. The haemograms of 29 of the resting horses were compared with the haemograms of the same 29 horses the following day at the race track. Both samples were considered to be representative of their reference populations. In general, there was a significant increase from the resting to prerace packed cell volume, haemoglobin, red cell count, white cell count and total plasma protein, although the extent of the increases varied between horses and, in a minority, levels were unchanged or decreased. The degree of variability in the prerace samples was not greater than that of the resting samples.