Current Research on Donkeys and Mules: Second Edition

A special issue of Animals (ISSN 2076-2615). This special issue belongs to the section "Equids".

Deadline for manuscript submissions: 31 October 2026 | Viewed by 2684

Special Issue Editors


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Guest Editor
1. Department of Animal Medicine and Surgery, University of Cordoba, Campus Rabanales, 14014 Cordoba, Spain
2. Veterinary Teaching Hospital, University of Cordoba, Campus Rabanales, 14014 Cordoba, Spain
Interests: donkeys; mules; clinical pathology; hematology; pathology; internal medicine
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Department of Animal Medicine and Surgery, University of Cordoba, Campus Rabanales, 14014 Cordoba, Spain
Interests: donkeys; mules; clinical pathology; hematology; pathology; internal medicine
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

We are pleased to open a new edition of this exciting and fruitful Special Issue, dedicated to the latest and most promising research on donkeys and mules. Although there is a growing interest in these species due to their more recent uses (milk and meat production, assisted therapy, and pet/companion animals), their traditional importance (packing and agricultural work), and the efforts to maintain endangered breeds all over the world, they are still neglected and forgotten in many scientific fields, with little to no specific information available on some topics. This brings new opportunities to researchers interested in characterizing their idiosyncrasies or specific attitudes. This Special Issue is aimed at highlighting species-specific findings in physiology, genetics, welfare, behavior, internal medicine, epidemiology, pathology, and pharmacology, along with any research showcasing new applications for these species. Comparative studies with other equids will also be of interest. Both reviews and original articles are welcome. By collecting manuscripts on a wide variety of cutting-edge topics, we hope to support these species and help to preserve and maintain their populations. We look forward to receiving your contributions.

Dr. Alejandro Pérez-Écija
Dr. Francisco Mendoza García
Guest Editors

Manuscript Submission Information

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Keywords

  • donkey
  • mule
  • internal medicine
  • behavior
  • pathology
  • clinical pathology
  • welfare
  • physiology
  • pathogens
  • milk
  • pharmacology

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Related Special Issue

Published Papers (4 papers)

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Research

16 pages, 1784 KB  
Article
Movement Ecology and Disease Exposure in Free-Roaming Donkeys in California, USA
by Sarah R. B. King, Amy McLean, Jacob D. Hennig and Kathryn A. Schoenecker
Animals 2026, 16(8), 1269; https://doi.org/10.3390/ani16081269 - 21 Apr 2026
Viewed by 218
Abstract
Feral donkeys (Equus asinus) are well adapted to arid ecosystems and are found in large populations in the deserts of Australia and the Americas. We assessed resource selection and seasonal home range size of female donkeys in southern California between 2020 [...] Read more.
Feral donkeys (Equus asinus) are well adapted to arid ecosystems and are found in large populations in the deserts of Australia and the Americas. We assessed resource selection and seasonal home range size of female donkeys in southern California between 2020 and 2022 based on telemetry data. We also examined whether dyads with greater encounter rates were more likely to test positive for asinine herpesvirus 5 (AHV-5) and/or Streptococcus equi zooepidemicus (SEZ). Donkey home ranges were non-significantly larger in the cool/wet season (November through March; mean 318.37 ± sd 417.65 km2) than in the hot/dry season (April through October; mean 159.35 ± 212.43 km2). Donkeys selected flatter areas closer to water year-round but selected greater herbaceous cover during the cool/wet season and lower heat loads during the hot/dry season. Individuals testing positive for SEZ selected lower elevations during the wet season and closer distances to water during the dry season; donkeys testing positive for AHV-5 selected areas farther from water during the wet season and steeper slopes during the dry season. The dyad encounter rate was unrelated to presence of either disease. Our results contribute to the understanding of donkey ecology, allowing feral populations to be better controlled by specific and focused management. Full article
(This article belongs to the Special Issue Current Research on Donkeys and Mules: Second Edition)
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15 pages, 604 KB  
Article
Both Season and Equid Type Affect Endogenous Adrenocorticotropic Hormone Concentrations in Healthy Donkeys, Mules and Hinnies in the United States
by Erin L. Goodrich, Sebastián Gonzalo Llanos-Soto, Renata Ivanek, Toby Pinn-Woodcock, Elisha Frye, Amy Wells, Stephen R. Purdy, Emily Berryhill and Ned J. Place
Animals 2026, 16(2), 290; https://doi.org/10.3390/ani16020290 - 16 Jan 2026
Viewed by 332
Abstract
Baseline plasma ACTH concentrations are frequently utilized as part of the diagnostic evaluation of equids when PPID is suspected. Baseline ACTH can be impacted by many factors including time of year, i.e., ACTH has generally been found to be elevated during late summer [...] Read more.
Baseline plasma ACTH concentrations are frequently utilized as part of the diagnostic evaluation of equids when PPID is suspected. Baseline ACTH can be impacted by many factors including time of year, i.e., ACTH has generally been found to be elevated during late summer through early autumn in the northern hemisphere. An understanding of ACTH concentrations in healthy equids over the course of a year is useful for the proper interpretation of concentrations in PPID-suspect animals. Previous studies assessing ACTH concentrations in healthy donkeys (Equus asinus) and hybrids (E. asinus × E. caballus) are limited, often utilizing very small numbers, equids from specific and limited geographical regions, limited timeframes or unspecified donkey types (miniature, standard, or mammoth). We aimed to characterize the seasonal variation in baseline ACTH concentrations in healthy miniature donkeys, standard donkeys and hybrids in the United States (US) and to compare those concentrations across these groups. Following outlier removal, 19 standard donkeys (from California (CA), Massachusetts (MA), New York (NY)), 14 miniature donkeys (CA and NY), and 28 hybrids (Texas (TX) and NY) were utilized for analysis. Samples were collected from each equid twice per month from June to November 2019 and once per month from December 2019 through May 2020. The mean ACTH concentration of all equids was higher from mid-August through the end of October compared to the rest of the year (being the highest in the second half of September with the mean (standard deviation) values of 109.6 (52.6), 134.6 (67.4), and 100.8 (189.6) in standard donkeys, miniature donkeys, and hybrids, respectively). Additionally, ACTH concentrations in hybrids were 23% (95% Confidence Interval (CI): 4–38%) and 51% (95% CI: 36–63%) lower than in standard and miniature donkeys, respectively, from mid-August through October. During the rest of the year, hybrids similarly showed 31% (95% CI: 16–43%) and 30% (95% CI: 15–42%) lower ACTH concentrations compared with standard and miniature donkeys, respectively. Full article
(This article belongs to the Special Issue Current Research on Donkeys and Mules: Second Edition)
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22 pages, 1543 KB  
Article
Morphological, Morphometric and Phaneroptic Variations of the Mediterranean Donkey and Tunisian Perspective on Conservation and Breeding
by Mohamed Aroua, Nour Elhouda Fehri, Antonella Fatica, Sana Khaldi, Samia Ben Said, Bayrem Jemmali, Mokhtar Mahouachi and Elisabetta Salimei
Animals 2026, 16(2), 207; https://doi.org/10.3390/ani16020207 - 9 Jan 2026
Viewed by 594
Abstract
The domestic donkey (Equus asinus) remains an essential component of agricultural systems worldwide, particularly in rural Tunisia. This study aims to conduct a comprehensive morphological characterization of the Tunisian donkey population, focusing on phaneroptic variation, sexual dimorphism and live weight prediction. [...] Read more.
The domestic donkey (Equus asinus) remains an essential component of agricultural systems worldwide, particularly in rural Tunisia. This study aims to conduct a comprehensive morphological characterization of the Tunisian donkey population, focusing on phaneroptic variation, sexual dimorphism and live weight prediction. A total of 556 clinically healthy donkeys, consisting of 207 males and 349 females, were sampled from various governorates in Tunisia. Descriptive statistics revealed significant variability in withers height (98–147 cm), thoracic circumference (100–165 cm) and body length (86–144 cm). Principal Component Analysis identified coat color and belly pigmentation as major contributors to phaneroptic variation, explaining 69.556% of the total variance. Hierarchical Ascendant Classification further classified the population into three distinct groups, with Group I exhibiting smaller body dimensions, Group II having medium sizes, and Group III consisting of larger donkeys. Sexual dimorphism was detected in neck circumference (females: 64.30 cm vs. males: 61.97 cm; FDR-adjusted p = 0.0468). Regression models for predicting live weight indicated that thoracic circumference was the most reliable single predictor (R2 = 95.4%). Overall, the study documents a wide range of morpho-biometric variation within the Tunisian donkey population and provides practical tools for field-based weight estimation, offering valuable insights for future conservation strategies and management programs. Full article
(This article belongs to the Special Issue Current Research on Donkeys and Mules: Second Edition)
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10 pages, 3078 KB  
Article
Pilot Study: Heart Rate and Heart Rate Variability Indices in Mules Evaluated by 24-Hour Electrocardiogram
by Lauren T. Maas, Jessica M. Morgan, Jordan Case, David D. Chell and Amy K. McLean
Animals 2025, 15(16), 2438; https://doi.org/10.3390/ani15162438 - 20 Aug 2025
Viewed by 1024
Abstract
Mules and donkeys are the 5th largest equine population in the U.S., yet basic information such as heart rate and arrhythmia prevalence in mules has not been described. Analysis of heart rate variability (HRV) provides valuable insight into physiologic and autonomic differences between [...] Read more.
Mules and donkeys are the 5th largest equine population in the U.S., yet basic information such as heart rate and arrhythmia prevalence in mules has not been described. Analysis of heart rate variability (HRV) provides valuable insight into physiologic and autonomic differences between mules, horses, and donkeys. We aimed to pilot the evaluation of heart rate and variability in a healthy population of mules using a 24 h electrocardiogram. Twenty-four-hour ambulatory electrocardiogram (aECG) recordings were collected from an athletic population of seven privately owned healthy mules in Northern California. Vision 5 Holter Analysis Software was utilized for ECG review and analysis. An average heart rate of 32–42 bpm, with a mean of 36 ± 3 bpm for 23.8 ± 0.2 h, was recorded. Minimum heart rate was 16–24 bpm, and maximum was 70–156 bpm. Individual mules had supraventricular complexes, sinoatrial heart block, and second-degree atrioventricular block during the observation period. Electrocardiographic evaluation of mules over 24 h found heart rate (HR) to be similar to horses and lower than in donkeys. Arrhythmias were consistent with the range of cardiac rhythms observed in horses and more frequent than reported in donkeys. Further investigation with a larger sample size of mules is warranted to determine if reference values for horses should continue to be used to assess mules and to investigate the prevalence of arrhythmias and their clinical relevance in the mule. Full article
(This article belongs to the Special Issue Current Research on Donkeys and Mules: Second Edition)
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