Abnormal behavior in donkeys is often dangerously subtle, and that subtlety is itself the core problem. Unlike horses, which tend to show obvious distress through flight, vocalization, and dramatic changes in movement, donkeys evolved as desert animals that fight rather than flee and express fear, pain, and discomfort in far more muted ways. A donkey in severe pain may simply become quieter, stand slightly apart from companions, or shift its weight in ways that only a trained observer would notice. Because of this stoicism, behavioral changes that seem minor can actually signal life-threatening disease.
The Stoic Problem
Donkeys are not stubborn versions of horses. They are a different species with a different evolutionary strategy, and that strategy shapes everything about how they communicate distress. Horses evolved on open grasslands where fleeing predators at speed was the primary survival mechanism. Donkeys evolved in arid, rocky terrain where running was often impractical, so they developed a “stand and fight” response instead. This means their behavioral repertoire under threat or pain is fundamentally different from a horse’s, and people accustomed to reading equine body language often miss or misinterpret donkey signals entirely.1Journal of Equine Veterinary Science. Donkeys Are Different
The practical consequence is stark. A horse with colic will typically pace, roll, kick at its belly, and show unmistakable signs of agitation. A donkey with colic may just stand quietly with its head slightly lowered. A horse with a painful hoof abscess will limp visibly. A donkey with the same abscess may continue walking with only a barely perceptible change in gait. Veterinary teams working with donkeys have recognized that subtle behavior change in the donkey can indicate severe, life-threatening disease, and that failing to recognize those changes is one of the most common reasons donkeys receive inadequate care.2UK-Vet Equine. Donkey and mule behaviour for the veterinary team
This does not mean donkeys feel less pain. Research into donkey pain expression has led to the development of species-specific tools like the Donkey Grimace Scale, which evaluates facial changes such as ear position, nostril shape, and tension around the eyes and lips. These grimace-based tools were created precisely because donkeys do not reliably show the whole-body distress signals that work as pain indicators in horses.3PubMed Central. Development of a Donkey Grimace Scale to Recognize Pain in Donkeys (Equus asinus) Post Castration
What Pain-Related Abnormal Behavior Actually Looks Like
When donkeys are in pain, particularly from musculoskeletal problems, the behavioral signs cluster around subtle postural changes rather than dramatic reactions. A study of working donkeys found that cumulative clinical scores for limb-related problems were associated with a higher frequency of leg trembling, knuckling of the forelimb, leg-lifting, and weight-shifting behaviors. All of these correlations were moderately strong. The same study found that donkeys with worse limb conditions were significantly less likely to stand bearing weight evenly on all four feet.4Veterinary Record Open. Clinical abnormalities in working donkeys and their associations with behaviour
These are not behaviors most owners would spontaneously flag as alarming. A donkey resting one leg slightly more than usual, or trembling faintly in a hind limb, could easily be dismissed as tiredness or normal resting posture. But when those behaviors become frequent or persistent, they correlate with real clinical pathology. The lesson for anyone caring for donkeys is that the baseline matters enormously. You need to know what your individual donkey looks like when healthy, including how it stands, how it distributes its weight, and how much it moves within a group, because deviations from that baseline are the main way a donkey “tells” you something is wrong.
Other pain-related behavioral changes include reduced appetite, reluctance to move, a dull or withdrawn facial expression, separation from herd mates, and loss of normal curiosity. Donkeys are naturally inquisitive animals, so a donkey that stops approaching people or investigating new objects in its environment is already showing a significant change. Grinding teeth, lip movements, or repeatedly rubbing the face against objects can sometimes indicate oral or dental discomfort, though these signs overlap with other causes and should be evaluated alongside physical examination.
Stress Behaviors Around Humans
Donkeys involved in animal-assisted therapy or educational programs interact with unfamiliar people regularly, and research on these interactions has revealed predictable patterns of stress-related behavior. A study examining how donkeys responded to different types of human interaction found that donkeys showed significantly more stress-related behaviors when humans were standing still near them or making physical contact than when humans were simply approaching from a distance. The stress response was also distance-dependent: donkeys at close range (within one to three meters) displayed significantly higher stress levels than those with more than three meters of space.5PubMed Central. Animal-Assisted Interventions: Factors Affecting Donkey Behaviours and Attitude Toward Humans
This finding may seem counterintuitive. You might expect a person standing still to be less threatening than one walking toward the donkey. But from the donkey’s perspective, an approaching human is a known quantity with a predictable trajectory, while a stationary human at close range is an ambiguous presence. Donkeys are wary animals that prefer to assess situations carefully, and the ambiguity of a still, nearby person may register as more unsettling than someone whose intentions are clear from their movement. Physical contact from an unfamiliar person was similarly stressful.
Stress behaviors in donkeys during these interactions include increased head-raising, attempts to move away, flattening of the ears, tension in the muzzle, tail swishing, and in more extreme cases, turning the hindquarters toward the person. For facilities using donkeys in therapeutic programs, this research underscores the importance of allowing donkeys to choose whether to engage, giving them adequate retreat space, and monitoring for these stress signals. A donkey that tolerates contact without showing overt aggression is not necessarily comfortable. It may simply be exhibiting the species-typical freeze-and-endure response rather than the horse-like bolt.
When Abnormal Behavior Appears Suddenly
Gradual behavioral shifts usually point to chronic issues like pain, arthritis, or poor husbandry. Sudden, dramatic behavioral changes demand a different set of considerations, because they can signal neurological disease, toxin exposure, or acute systemic illness.
Poisoning is an underappreciated cause of sudden abnormal behavior in donkeys, especially in regions where they graze freely on mixed vegetation. In northeastern Brazil, donkeys and sheep that ingested the flowering plant Brunfelsia uniflora at the start of the rainy season developed severe convulsions and diarrhea after eating roughly ten grams per kilogram of body weight. The nervous signs appeared acutely and were directly tied to the plant’s flowering period.6PubMed Central. Poisoning by Brunfelsia uniflora in sheep and donkeys While this particular plant is geographically specific, the broader principle holds everywhere: donkeys that have access to pasture, hedgerows, or garden clippings can encounter toxic plants, and seizures, tremors, incoordination, or sudden mania should trigger immediate consideration of plant or chemical exposure.
Rabies, though rare in donkeys, is another cause of acute behavioral change that must not be overlooked in areas where the disease is endemic. During two livestock rabies outbreaks in Shanxi province, China, one donkey died from the virus, and brain samples confirmed rabies virus by laboratory testing.7PubMed. Livestock rabies outbreaks in Shanxi province, China In rabies cases, affected animals may show unprovoked aggression, excessive salivation, difficulty swallowing, and progressive paralysis, all of which represent dramatic departures from normal donkey temperament. Any donkey exhibiting these signs after potential exposure to wildlife, stray dogs, or other animals of unknown vaccination status should be treated as a potential rabies case with appropriate precautions.
Other infectious causes of sudden behavioral abnormality include equine encephalitis viruses, tetanus, and meningitis. Metabolic emergencies like hyperlipemia, which donkeys are particularly susceptible to, can also cause depression, disorientation, and behavioral dullness. Hyperlipemia tends to develop when a donkey stops eating for any reason, including stress from transport, a change in companions, or dental pain. Fat is mobilized into the bloodstream at rates the liver cannot handle, and the resulting toxicity affects the brain among other organs. The behavioral sign is often just a donkey that seems “not right,” standing quietly and showing little interest in food or surroundings.
Abnormal Maternal Behavior
Foal rejection is one of the most striking and distressing forms of abnormal behavior in equids. While much of the published research has focused on horses rather than donkeys specifically, the phenomenon has clear relevance across equid species. A study of foal rejection in Arabian mares documented that rejecting mares were more likely to avoid, threaten, squeal at, chase, bite, and kick their foals after birth compared to non-rejecting mares. Non-rejecting mares were more likely to lick, nicker at, and defend their offspring. The study also found no statistically significant relationship between foal rejection and breeding method, the presence of people at birth, the presence of other horses nearby, or whether the first nursing was assisted. However, the presence of certain sires in the pedigree of rejecting mares was statistically higher, suggesting a heritable component to the behavior.8PubMed. Prevalence and characteristics of foal rejection in Arabian mares
In donkeys, foal rejection has been reported but is less well studied. The signs mirror those documented in horses: a jenny that pins her ears, moves away from the foal, or actively threatens or attacks it after birth is showing rejection behavior that requires immediate intervention. First-time mothers (maiden jennies) are at higher risk, as are those that experienced a difficult delivery. Separating the pair and allowing supervised reunions, sometimes with mild sedation or physical restraint of the dam, can resolve mild cases. In severe cases, the foal may need to be hand-reared or fostered onto another lactating jenny.
Abnormal maternal behavior can also manifest more subtly as failure to bond. A jenny that allows the foal to nurse but does not lick it, does not nicker in response to its calls, and does not position herself protectively near it is showing a form of passive rejection. This may resolve over several days as hormonal bonding processes catch up, but it warrants close monitoring because a foal without active maternal protection is vulnerable to injury from other animals in the group.
Cognitive Decline in Older Donkeys
Donkeys live a long time compared to many domestic animals, routinely reaching their thirties and sometimes their forties. As they age, some develop behavioral changes that resemble cognitive decline in other species. A post-mortem study of thirteen donkeys aged between 33 and 44 years, along with two younger controls aged eight and nine, examined their brains for signs of neurodegeneration. Amyloid plaques were identified in nine of the aged donkeys, and structures resembling neurofibrillary tangles were found in seven. Neither pathology was present in the younger animals. Interestingly, the oldest donkey in the sample, at 44 years of age, showed neither type of brain lesion, which suggests these changes are not simply an inevitable part of donkey aging.9Oxford Academic (Brain Communications). Spontaneous mammalian models for Alzheimer’s disease and dementia
The behavioral implications are significant. Owners of elderly donkeys sometimes report changes such as getting lost in familiar spaces, standing facing a wall or fence corner, failure to recognize familiar handlers, disrupted sleep-wake cycles, loss of established social hierarchies, and reduced responsiveness to environmental cues. These signs overlap with what has been described as cognitive dysfunction syndrome in dogs and horses, and the neuropathological findings in donkeys suggest a similar underlying process. However, because the condition is still poorly characterized in donkeys, there is no standard diagnostic protocol. Any elderly donkey showing progressive behavioral changes should be evaluated for treatable conditions like pain, dental disease, and metabolic problems before cognitive decline is assumed.
Stereotypic Behaviors and Environmental Causes
Stereotypies are repetitive, apparently functionless behaviors that develop in captive or confined animals, and donkeys are no exception. The most common stereotypic behaviors observed in donkeys include weaving (swaying the head and neck from side to side while shifting weight between the front legs), cribbing (grasping a fixed surface with the teeth and pulling back while gulping air), and wood chewing. Head bobbing, wall kicking, and circling within a stall also occur.
These behaviors are widely understood to be signs of compromised welfare, not “bad habits” that develop randomly. They typically emerge in donkeys that are:
- Socially isolated: Donkeys are herd animals with intense social bonds, and housing a donkey alone is one of the strongest predictors of behavioral abnormality. A single donkey separated from companions will often develop depression-like withdrawal, vocalize excessively, or begin stereotypic behavior within days to weeks.
- Physically confined: Donkeys that spend most of their time in small stalls or yards without room to move, forage, and explore are far more likely to develop repetitive behaviors than those with access to pasture or large paddocks.
- Deprived of forage: In the wild and in natural grazing conditions, donkeys spend the majority of their waking hours browsing and walking. When their diet is delivered in concentrated meals with long gaps between them, the unoccupied time creates conditions ripe for stereotypy development.
Once stereotypies are established, they can persist even after the triggering conditions are corrected. A donkey that developed weaving during a period of solitary confinement may continue weaving for months or years after being returned to a social group. This is because the behavior appears to become self-reinforcing through neurological pathways, similar to what happens with compulsive behaviors in other species. Prevention through adequate social housing, space, and forage access is far more effective than trying to stop stereotypies after they have taken root.
Aggression That Is Not What It Seems
Donkey aggression toward humans or other animals is perhaps the behavioral category most likely to be misread. Donkeys that bite, kick, charge, or refuse to be caught are frequently labeled as “mean” or as having a bad temperament, when in reality the aggression almost always has a specific cause. Pain is at the top of the list. A donkey with a sore back that bites when a saddle is placed, or one with hoof pain that kicks when a leg is lifted for trimming, is not displaying a character flaw. It is communicating the only way it can that the handler’s actions are causing or worsening pain.
Fear-based aggression is the second major category. Because donkeys tend to freeze and fight rather than flee, a frightened donkey that feels cornered may strike out with its front hooves, swing its hindquarters to kick, or bite. This is especially common in donkeys that have been inadequately handled or have experienced rough treatment in the past. Unlike horse aggression, which often involves bolting and kicking during flight, donkey aggression tends to be deliberate and targeted because the animal is standing its ground rather than trying to escape.
Intact male donkeys (jacks) can show hormonally driven aggression that goes beyond what is typical in stallions. Jacks may attack other equids, dogs, and even humans, and are well known for their willingness to confront and kill small predators and canids. This trait has been deliberately exploited in some agricultural settings by using guard donkeys to protect livestock from coyotes and foxes. But in a domestic context, a jack’s territorial and sexual aggression can become genuinely dangerous if not managed through appropriate housing, handling, and in some cases gelding.
Reading the Whole Picture
One of the most persistent mistakes in evaluating donkey behavior is looking at a single sign in isolation. A donkey that stops eating, for example, could be experiencing dental pain, gastric ulcers, hyperlipemia, a change in social dynamics, grief after losing a companion, or the early stages of an infectious disease. The same is true for a donkey that seems unusually aggressive, withdrawn, or restless. Individual behavioral signs in donkeys are nonspecific. They gain meaning only in context: what is the donkey’s age, sex, social situation, workload, diet, environment, and medical history? Has something changed recently? What does the donkey look like when it is well?
Veterinary professionals working with donkeys increasingly emphasize the importance of owner-reported behavioral baselines, because the owner who sees the animal every day is far better positioned to detect the kind of subtle shift that signals trouble than a clinician seeing the animal for the first time. Keeping informal notes on your donkey’s normal habits, appetite patterns, social preferences, and posture can make the difference between catching a problem early and missing it until the animal is in crisis. Donkeys are not dramatic about their suffering, and that is exactly why paying attention to the undramatic matters so much.