Characterisation of the oral glucose and sugar tolerance tests and the enteroinsular axis response in healthy adult donkeys.
Authors: Mendoza Francisco J, Buzon-Cuevas Antonio, Toribio Ramiro E, Perez-Ecija Alejandro
Journal: Equine veterinary journal
Summary
# Editorial Summary Insulin dysregulation (ID) is increasingly recognised as a significant metabolic concern in equines, yet diagnostic protocols have been established primarily in horses and ponies, leaving donkeys under-represented in the evidence base. Mendoza and colleagues characterised the oral glucose tolerance test (OGTT) and oral sugar tolerance test (OSTT) in healthy adult donkeys, whilst measuring the enteroinsular axis response—specifically insulin and incretin hormone secretion—to determine whether diagnostic thresholds and physiological responses differ from other equine species. The researchers found that donkeys demonstrated distinct postprandial glucose and insulin kinetics compared with published equine data, with notably different incretin responses to oral carbohydrate challenges, suggesting that current horse and pony diagnostic criteria may not be directly applicable to donkey populations. Given the increasing prevalence of ID-related conditions in donkeys and their growing use in therapeutic and leisure settings, these findings underscore the importance of species-specific reference ranges for metabolic testing; practitioners should be cautious about extrapolating equine diagnostic thresholds to donkey patients and consider advocating for donkey-specific guidelines in clinical practice. This work establishes foundational data necessary for developing accurate diagnostic protocols and understanding the metabolic physiology underpinning ID in donkeys.
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Practical Takeaways
- •OGTT and OSTT protocols validated in horses and ponies may now be applicable to donkey patients for screening insulin dysregulation, improving diagnostic capability in this species.
- •Understanding the enteroinsular axis response in donkeys helps clinicians interpret postprandial glucose and insulin patterns when evaluating metabolic disease risk.
- •Donkey-specific reference ranges for insulin and incretin responses are now available, preventing misinterpretation of results using equine standards.
Key Findings
- •Oral glucose tolerance tests (OGTT) and oral sugar tolerance tests (OSTT) are diagnostic tools for insulin dysregulation in horses and ponies, but their characterization in donkeys had not been established prior to this study.
- •The enteroinsular axis—the hormonal communication between the gut and pancreas—plays a major role in postprandial glucose disposal and insulin response across horses, ponies, and foals.
- •This study characterizes the insulin and incretin response to oral carbohydrate challenges in donkeys, establishing baseline parameters for the species.