Can animals have mental illness?

The health of the mind has traditionally been understood as an anthropocentric reality , the exclusive heritage of our species. Animals, despite their quality as living beings, would thus be devoid of the intellect and sensitivity necessary to suffer emotionally.

The truth, however, is that every emotion that we can experience comes from very ancient brain areas phylogenetically, shared with countless other organisms that populate this planet. Therefore, it should not be strange that we also had in common some emotional experience, and perhaps even some problem in this area.

To dispossess the rest of the animals of everything that could bring them closer to our reality would position them in an ideal setting to be used as a fungible resource, in all the areas in which they were susceptible to it (livestock, industry, etc.).

In this article we will abound in the empirical evidence that allows us to answer the simple question of: can animals have mental illness? The purpose of the text is to better understand the way in which they suffer from emotional distress and what situations precipitate it.

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Can animals have mental illness?

In recent years, society has sharpened its sensitivity to the subjective experience of animals, so that there is even a scientific specialty (Animal Psychopathology) aimed at studying this phenomenon. In this text, eight of the most common emotional problems that can present will be cited.

1. depression

Depression is described as a state of sadness and decreased ability to feel pleasure (anhedonia), resulting from a loss perceived as significant. It is one of the great disorders of our time, and there are signs that animals can also suffer it when exposed to specific situations; such as a loss of control over the environment, a reduction of incentives and even the death of a member of your group.

The first scientific descriptions of animal depression come from works on learned helplessness, at a time in history when the ethical guarantees of laboratories were more lax than at present. These investigations tried to explore the negative affective reactions of a living being when experiencing adverse circumstances over which it lacked control.

Models were sought that allowed generalizing any finding to man, with the aim of extracting environmental risk factors that could predict the decline of his mood. In these studies it was used to introduce a dog into a special cage, at the base of which two separate metal surfaces were located, which covered the entire length of it.

The experimenter proceeded to electrify one of them, to which the animal responded by changing its location and locating itself where the stimulus was not present (in the sheet without electricity). The dog repeated it without problems on all occasions when the experimental condition was administered, with which he could assume effective control over his own environment (experiencing a discomfort that did not extend beyond a brief moment).

After several trials, the researcher would apply the electric current to the two surfaces simultaneously, so that the dog found no shelter on either side of the cage. In this case, he would try to find a place where his discomfort would end first, but when corroborating the absence of viable options, he would adopt a dejected attitude. Thus, he would lie down to support all the discharges with a very deep apathy, developing a progressive abandonment of his most basic needs.

With studies like this, not only was evidence obtained about how depression is triggered in humans, but similar emotional states could be inferred in other animals .

2. Duel

Some mammals (such as elephants or chimpanzees) seem to have a precise idea of ​​what death is, and even develop parting “rituals” upon the death of a member of their herd . In fact, there is evidence that they are not only aware of the finiteness of their organism, but that they also have rules regarding what is considered “good” or “bad”, adapting these notions to the field of life and life. death (looking for the first and fearing the second).

These animals go through a process of mourning at the loss of a loved one, in a very similar way to what has been described in classic models for humans. They can resort to physical spaces in which to watch over the remains of those who preceded them (“cemeteries” near rivers in which the corpses of dying elephants that tried to drink in their last death rattle accumulate), and even show behaviors suggestive of be dealing emotionally with absence (such as reduced food intake, sleep disturbance, etc.).

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3. Suicide

There is evidence of marine mammals (such as dolphins) that may make the decision to kill themselves in certain circumstances , both in the wild and in captivity.

The mechanism they usually use is to beach their bodies on the coasts or on the shores, on a terrestrial surface on which their tissues suffer until death. There have been many causes that have been postulated for this tragic phenomenon, until recently restricted to the human sphere.

The research carried out in this regard yields two different conclusions: that the dolphin’s autolytic behavior is due to a spatial disorientation resulting from the use of sonars and other human technologies, or that it may be the consequence of unbearable suffering derived from physical pathology. In the latter case, it would be a behavior analogous to that which can be observed in humans , when suicide is motivated by a state of very intense organic or emotional pain.

4. Addictions

Animal addictions are very rarely observed when living in the wild , so the evidence for them comes from laboratory studies. Thus, it has been observed that rats and mice show a preference for water mixed with substances such as cocaine, or simply with sugar (which is a natural enhancer), and the existence of the fundamental symptoms of any addiction has been demonstrated. : tolerance (need to consume a larger quantity of the drug to achieve the same effect) and withdrawal syndrome (discomfort in the absence of the substance).

And it is that the brain structures involved in addiction, the nucleus accumbens and the ventral tegmental area, are common to a wide variety of animals. Dopamine would be the neurotransmitter that would orchestrate the neural network; activating before the stimuli that facilitate survival (sex, food, etc.), generating pleasure (high hedonic tone) and increasing motivation for them. The effect of the drug would alter its allostasis and reduce the search for what was once gratifying, which would end up completely dominating the behavior of the animal.

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5. Activity anorexia

Activity anorexia is an eating disorder that has been observed in rats in laboratory conditions, when their access to food is restricted and the indiscriminate use of a wheel in which to exercise is allowed . In conditions in which both elements are present, the animal learns to make proper use of them, but in the new situation, it resorts to physical exercise until exhaustion or even death.

When the problem is consolidated, the animal persists in this pattern (poor feeding and intense physical exercise), even after restoring normal access to food. Theories suggest that it is a behavior aimed at promoting the search for a new environment when the previous one has stopped providing the material sustenance necessary to guarantee the maintenance of life.

6. Pica

Pica is an eating disorder in which the subject ingests non-nutritive elements, such as sand or clay, and may suffer parasitic infections or damage to the digestive system. This behavior has been observed in farm animals subjected to the restriction of basic nutrients , such as feed or grain, who develop the habit of eating inorganic elements (wood, plastics, etc.) whose digestion may be impossible. These animals include roosters, chickens, and other poultry.

On other occasions, the deficiency situation (in phosphorus) would make it easier for herbivorous animals to nibble on bones in order to compensate for their deficit (osteophagy). Although it is an adaptive behavior, it can persist despite reestablishing appropriate diets, which would dilute its usefulness for survival. Finally, the problem has also been evident in cats, in which the intake of threads or fabrics can be seen, which can cause very serious problems in the intestines.

7. Ritualized behaviors

Ritualized behaviors frequently occur in wild animals that are subjected to states of captivity, in which they have a very different physical space than they could enjoy in freedom. These are repetitive behaviors that lack a clear purpose , and that do not contribute to the satisfaction of the essential needs for their survival. They have been described in a wide variety of animals, and suppose an aberration of habits that incapacitates them to reintegrate into nature.

In birds, alterations in singing and pecking have been observed, which erode the ability to communicate with other individuals and damage the structure of the organs necessary for feeding and cleaning. It is also common in animals used for show or exhibition, such as rhinos and cats, that when living in confined spaces for a long time, their motor skills are altered (limiting themselves to turning in small diameter circles even when they are released into their environment of origin. ).

8. Stress

Stress is a physiological response common to many species, and not exclusively human. There are many situations that can cause stress to an animal: from its confinement to reduced spaces to excessive manipulation (by people) or isolation from other members of its species. This last factor is key in certain primate varieties , which live inserted in hierarchical communities and which can have disparate levels of stress depending on their place in them (higher among intermediate-level non-dominant males).

It has also been observed that social and environmental isolation can lead to self-injurious actions in many animal species, especially primates and birds, which can harm themselves when they are caged or isolated from the environment (in socially poor spaces). Common self-punitive actions involve scratches and bites on different parts of the body, as well as plucking plumage from birds.


Animals are susceptible to emotional problems , especially when they are removed from their natural environment (in zoos, circuses, etc.). Research on this issue is currently increasing, and it is expected that in the future it will become an area of ​​deep scientific interest.


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