Reference ranges and the influence of age and sex on hematologic and serum biochemical values in donkeys (Equus asinus)

Hematologic and serum biochemical values were determined in blood samples from 217 donkeys (Equus asinus). Donkeys were classified on the basis of size, sex, age, and whether they were domestic or feral. Parametric (mean +/- 2 SD) and nonparametric (2.5th to 97.5th percentile) reference ranges were calculated for each analyte. For all donkeys, 26 of 46 analytes significantly departed from gaussian distribution. Serum lactate dehydrogenase activity in miniature donkeys was higher than that in other donkeys. Differential leukocyte counts in feral donkeys differed from those in other types in ways that suggested that the former had smaller parasite loads or experienced greater stress. Erythrocyte, lymphocyte, and platelet counts and fibrinogen, glucose, inorganic phosphorus, and potassium concentrations decreased with age. Eosinophil counts, mean corpuscular volume, and plasma protein, serum protein, and serum globulin concentrations increased with age. Female donkeys had significantly (P less than 0.05) higher mean corpuscular hemoglobin concentration and leukocyte and neutrophil counts than did male donkeys. Mean corpuscular hemoglobin increased with age, and females had higher values than did males of all age groups. An interaction between age and sex was observed for alkaline phosphatase activity, with a trend for decreased activity with age.