LEUKOCYTE COUNTS IN THE HEALTHY ENGLISH THOROUGHBRED IN TRAINING

Total and different leukocyte counts were determined by electronic counting techniques in 474, 2- to 4-yr-old healthy thoroughbreds in training. The ranges of values observed (particularly those for neutrophils and lymphocytes) were narrower than previously described. Absolute and percentage lymphocyte values were significantly decreased with advancing age causing a relative increase in percentage neutrophils. The fall in absolute lymphocyte numbers was the main cause for a significant decrease in total leukocytes with age. Frequency plots for each variable showed that, with the exception of the eosinophil count, data from other leukocyte cell types following either a normal or lognormal distribution.