Donkey and Mule Medicine for Veterinarians: Key Clinical Differences Every Practitioner Should Know
Donkeys and mules are increasingly common patients in equine practice – yet they remain some of the least well-understood equids in veterinary education.
Despite superficial similarities to horses, donkeys and mules differ in anatomy, physiology, behaviour, pharmacology, and pain expression in ways that directly influence clinical decision-making.
Treating them as “small horses” or “horses with long ears” risks misinterpretation of clinical signs, inappropriate drug dosing, and avoidable complications during routine procedures.
This article summarises key clinical insights from the Introduction to Donkey and Mule Medicine lecture, presented by Dr. Amy McLean (UC Davis) and Dr. Claude Ragle (Washington State University) – two internationally recognised experts in donkey and mule medicine – and highlights why species-specific knowledge is essential for modern veterinary practice
Donkeys and Mules Are Not Horses: Why This Matters Clinically
One of the most important concepts for veterinarians to understand is that donkeys evolved in arid, resource-limited environments, while horses evolved in grassland systems. This evolutionary divergence has shaped everything from metabolism and thermoregulation to behaviour and anatomy.
In practice, this means:
- Normal reference ranges may differ
- Disease can present more subtly
- Behavioural responses to pain and restraint are not the same
- Common procedures (venipuncture, intubation, ophthalmic exams) may be more challenging
Recognising these differences early improves diagnostic accuracy and client confidence.
Key Anatomical Differences That Affect Everyday Procedures
Jugular Vein Access and Catheter Placement
Donkeys have a thicker cutaneous colli muscle overlying the jugular vein, an adaptation related to intraspecies fighting behaviour. The vein is often smaller in diameter and more mobile, making venipuncture and catheter placement more difficult than in horses.
Mules, by contrast, tend to resemble horses more closely in jugular anatomy – though individual variation remains significant.
Head, Skull, and Ophthalmic Considerations
Donkeys have:
- Thicker frontal and occipital bones
- Narrower orbital access
- Anatomical features that make ocular examination more difficult
Routine eye exams that are straightforward in horses may require nerve blocks or alternative handling strategies in donkeys and some mules.
Airway and Upper Respiratory Anatomy
Differences in:
- Laryngeal anatomy
- Airway angle
- Guttural pouch access
can influence endoscopy, intubation, and anesthetic management. Smaller diameter endotracheal tubes are often required, and resistance during passage is more common.
Physiological Differences: Why “Normal” Isn’t Always Normal
Temperature, Pulse, and Respiration
- Donkeys typically have a lower baseline temperature than horses
- Mules may fall closer to horses, while hinnies tend to resemble donkeys
- Pulse and respiratory rates can be higher than expected
Without species-appropriate context, these values may be misinterpreted during routine exams or emergency presentations.
Metabolism and Nutrition
Donkeys evolved under feast-and-famine conditions and appear to possess a “thrifty” metabolic strategy, efficiently storing energy when forage is abundant.
This adaptation increases the risk of:
- Obesity
- Hyperlipemia
- Metabolic disease
when donkeys are managed like horses on unrestricted pasture.
Behaviour, Pain, and Clinical Interpretation
Donkeys and mules often display a stoic response to pain, particularly compared with horses. Rather than overt lameness or dramatic behavioural change, illness may present as:
- Subtle withdrawal
- Reduced interaction
- Quiet demeanour
This makes early disease detection more challenging and places greater emphasis on careful physical examination and contextual interpretation.
From a handling perspective:
- Donkeys are more likely to freeze and resist rather than flee
- Mules may be more reactive during procedures
- Both species are highly intelligent and quickly learn from negative experiences
Understanding these behavioural tendencies improves both safety and compliance.
Sedation, Analgesia, and Medication Challenges
Donkeys and mules often respond differently to sedatives and analgesics than horses. Key considerations include:
- Altered drug metabolism
- Variable sedation depth at standard equine doses
- Difficulty administering oral medications (including deliberate retention and expulsion)
These challenges have driven research into alternative approaches, including transdermal analgesics, which have shown promising results in donkeys.
Why Hybrid Equids Require a Thoughtful Approach
Mules and hinnies combine traits from both horses and donkeys – but they are not predictable averages.
When breeding history is unknown (which is common), treating hybrids clinically as mules rather than horses or donkeys alone provides a safer baseline approach.
Want to See This Applied Clinically?
This article only scratches the surface of the full lecture.
A 5-minute video preview is available below where Dr. McLean and Dr. Ragle:
- Walk through real clinical examples
- Explain why these differences matter in practice
- Demonstrate the depth and practicality of the full training
Access the Full Lecture – and 200+ More
Introduction to Donkey and Mule Medicine is part of the Practitioner’s Program, a comprehensive postgraduate education library created specifically for veterinary practitioners.
Inside the program, you’ll find:
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- ✅ 200+ on-demand veterinary training videos
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