Comparative Clinical Pathology

, Volume 25, Issue 4, pp 871–878 | Cite as

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

  • Amy K. McLeanEmail author
  • Wei Wang
  • Francisco Javier Navas-Gonzalez
  • João B. Rodrigues
Original Article


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.


Mules Hinnies Donkeys Blood chemistry Hematology 



The authors would like to express sincere gratitude and thanks to Dr. Jesus of Toro, Spain, for donating many of the animals used in this study as well as helping identify other owners and clients with equines that were sampled. We would also like to thank all clients in Miranda, Portugal, and Toro, Spain, who were a part of this study.

Compliance with ethical standards

Informed consent was obtained from all individual participants included in the study. All owners/clients agreed to a consent either in written form for Spanish owners or verbal for the Portuguese to allow their animals to be subjected to sampling for this study. Consents were relayed in the appropriate language, Spanish and Portuguese. In addition, the protocol was approved by the North Carolina State University Animal Care and Use Committee (approval #13-039-A).

Conflict of interest

There is no conflict of interest for any of the authors. Author McLean did receive funding from North Carolina State University and a previous institution, University of Wyoming, but the remaining authors had no other funding or conflicts.


Author McLean received two grants, one from the University of Wyoming College of Agriculture Department, Global Perspectives and an International Seed Grant, and funds from her startup package at North Carolina State University Animal Science Program that helped fund this project.


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Copyright information

© Springer-Verlag London 2016

Authors and Affiliations

  • Amy K. McLean
    • 1
    Email author
  • Wei Wang
    • 2
  • Francisco Javier Navas-Gonzalez
    • 3
  • João B. Rodrigues
    • 4
  1. 1.Animal ScienceNorth Carolina State UniversityRaleighUSA
  2. 2.Palo Alto Medical Foundation Research InstitutePalo AltoUSA
  3. 3.Genetics Department, Veterinary SciencesUniversity of CórdobaCórdobaSpain
  4. 4.FMV-ULHT, Faculty of Veterinary MedicineUniversity Lusófona de Humanidades e TecnologiasLisbonPortugal

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