Reference intervals for hematological and blood biochemistry reference values in healthy mules and hinnies

Little scientific information is known regarding mules and even less is known about hinnies. Due to increased popularity of both as recreational animals which are still commonly found as working equids, there is a need for such basic information for practitioners and owners. The purpose of this study was to begin to establish reference ranges for hematological and biochemical parameters of clinically healthy mules and hinnies compared to those of their sires and dams (horses and donkeys of similar genotype, phenotype within species) used for hybrid offspring production. Such information will contribute to our understanding and attempts to improve management and disease diagnosis of hinnies and mules. Eighty-one healthy equids (n = 30 hinnies, 20 mules, 20 donkeys, and 11 horses) were sampled. Clinical data recorded age, gender, BCS, and temperature. Two 10-mL blood samples were collected by venipuncture of the jugular vein, using “vacutainer” plain and EDTA tubes. These samples were analyzed for RBC, PCV, Hb, WBC, platelets, proteins, fatty acids, electrolytes, enzymes, and glucose. Average and standard deviations were calculated. Kruskal-Wallis test was used to test the significant value. Findings were considered to be significant if P ≤ 0.05. When comparing all parameters among four groups of equids, differences were found for temperature, red blood cell lines, white blood cell lines, electrolytes, and enzymes. Differences in mules and hinnies were seen in RBC, WBC, magnesium, bilirubin, creatinine, and AST. The results are constricted to very few known populations of equid hybrids with similar genetics. In this study, hinnies and mules showed results that were closer to those of horses than those of donkeys. Some differences recorded in hinnies may be related to age: RBC, WBC, MCH, MCV, eosinophils, magnesium, total bilirubin, creatinine, and AST. Findings may help establish new, relevant hematological and biochemical parameters which may prevent medical misdiagnosis. Additional research is needed with larger populations of healthy mules and hinnies.