Can animals have mental illnesses?
Are mental disorders unique to the human species, or do they also appear in other animals?
The health of the mind has traditionally been understood as an anthropocentric reality, the exclusive patrimony of our species.The health of the mind has traditionally been understood as an anthropocentric reality, the exclusive patrimony of our species. Animals, despite their quality as living beings, would thus be deprived of the intellect and sensitivity necessary to suffer at the emotional level.
What is certain, however, is that any emotion we may experience comes from phylogenetically very ancient brain areas, shared with countless other organisms that populate this planet. Therefore, it should not be strange that we also have in common some affective experience, and perhaps even a problem in this area.
To deprive the rest of the animals of everything that could bring them closer to our reality would place them in an ideal scenario to be used as a fungible resource, in all areas where they are susceptible to this (livestock, industry, etc.).
In this article we will abound in empirical evidence that allows us to answer the simple question: can animals have mental illnesses? The purpose of the text is to learn more about how they suffer from affective distress and what situations precipitate it.
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Can animals have mental illnesses?
In recent years, society has become more sensitive to the subjective experience of animals, so that there is even a scientific specialty (Animal Psychopathology) aimed at the study of this phenomenon. In the present text, eight of the most common emotional problems that may occur will be mentioned.
Depression is described as a state of sadness and decreased capacity for pleasure (anhedonia) resulting from a perceived significant loss. It is one of the great disorders of our time, and there is evidence that animals can also suffer from it when exposed to specific situations, such as a loss of control over the environment, a reduction in incentives and even the death of a member of their group.
The first scientific descriptions of animal depression come from work on learned helplessness, at a time in history when ethical safeguards in laboratories were more lax than they are today. These investigations sought to explore the negative affective reactions of a living being when experiencing adverse circumstances. over which he had no control.
Models were sought that would allow any findings to be generalized to humans, with the aim of extracting environmental risk factors that could predict the decline of their mood. In these studies, a dog was usually placed inside a special cage, at the base of which two separate metal surfaces were placed, which covered the entire length of the cage.
The experimenter proceeded to electrify one of them, to which the animal responded by changing its location and placing itself where the stimulus was not present (on the sheet without electricity). The dog repeated this without any problems on every occasion that the experimental condition was administered, thus The dog was able to assume effective control over its own environment (experiencing discomfort that did not extend beyond a brief moment).
After several trials, the investigator would apply the electric current to both surfaces simultaneously, so that the dog would find no shelter on either side of the cage. In this case, it would first try to look for a place where its discomfort would end, but when it corroborated the absence of viable options, it would adopt a dejected attitude. Thus, he would lie down to endure all the discharges with a very deep apathy, developing a progressive abandonment of his most basic needs.
With studies such as this one, not only was evidence obtained on how depression is triggered in humans, but it was also possible to infer similar emotional states in others. inferred similar emotional states in other animals..
Some mammals (such as elephants or chimpanzees) seem to have a precise idea of what death is, and even develop "rituals" to say goodbye. develop farewell "rituals" when a member of their herd dies.. In fact, there is evidence that they are not only aware of the finiteness of their organism, but also have rules regarding what is considered "good" or "bad", adapting these notions to the realm of life and death (seeking the former and fearing the latter).
These animals go through a mourning process in the face of the loss of a loved one, in much the same way as described in the classical models for humans. They may even resort to physical spaces in which to mourn the remains of those who preceded them ("cemeteries" near rivers where corpses of dying elephants that tried to water in their last breath accumulate), and even show behaviors suggestive of dealing affectively with the absence (such as reduced food intake, sleep disturbance, etc.).
There is evidence of marine mammals (such as dolphins) that may take can make the decision to take their own lives in certain circumstances, both in the wild and in captivity.both in the wild and in captivity.
The mechanism they usually use consists of stranding their body on the shore or on the shore, on a land surface on which their tissues suffer until death. Many causes have been postulated for this tragic phenomenon, until recently restricted to the human sphere.
The research carried out on this subject has yielded two different conclusions: that the dolphin's autolytic behavior is due to a spatial disorientation resulting from the use of sonar and other human technologies, or that it may be the consequence of unbearable suffering derived from a physical pathology. In the latter case, it would be a behavior analogous to that which can be observed in the human being, when the suicide is motivated by a very intense organic or emotional pain.when the suicide is motivated by a state of very intense organic or emotional pain.
Addictions in animals are very rarely observed when they live in the wild.Therefore, the evidence on these addictions 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 (the need to consume a greater quantity of the drug to achieve the same effect) and withdrawal syndrome (discomfort in the absence of the substance).
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 in the face of 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, so that it would end up completely dominating the animal's behavior.
- You may be interested in, "Addiction: disease or learning disorder?"
5. Activity anorexia
Activity anorexia is an eating behavior disorder that has been observed in rats under laboratory conditions, when their access to food is restricted and indiscriminate use of a wheel on which to exercise is allowed.. In conditions where 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 re-establishing normal access to food. Theories suggest that this is a behavior aimed at promoting the search for a new environment when the previous one has ceased to provide the material sustenance necessary to ensure the maintenance of life.
Pica is an eating disorder in which the subject ingests non-nutritive elements, such as sand or clay, and may suffer from parasitic infections or damage to the digestive system. This behavior This behavior has been observed in farm animals subjected to basic nutrient restriction.The animals, such as feed or grain, that develop the habit of eating inorganic elements (wood, plastics, etc.), the digestion of which may be impossible. Among these animals are roosters, hens and other poultry.
On other occasions, the deficiency situation (in phosphorus) would make it easier for herbivorous animals to nibble bones in order to compensate for their deficit (osteophagia). Although this is an adaptive behavior, it may persist despite the reestablishment of appropriate diets, thus diluting its usefulness for survival. Finally, the problem has also been observed in cats, in which the ingestion of threads or fabrics that can cause very serious problems in the intestines has been observed.
7. Ritualized behaviors
Ritualized behaviors occur frequently in wild animals that are subjected to a state of captivity, in which they have a physical space that is very different from the one they would enjoy in the wild. These are repetitive behaviors that lack a clear purpose and do not contribute to the satisfaction of the animal's needs.They are repetitive behaviors that lack a clear purpose and do not contribute to the satisfaction of essential survival needs. They have been described in a wide variety of animals, and represent an aberration of habits that makes them unable to reintegrate in 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 grooming. It is also common in animals used for show or exhibition, such as rhinoceroses and felines, which, living in confined spaces for long periods of time, have their motor skills altered (limited to circling in small diameter circles even when released back to their original environment).
Stress is a physiological response common to many species, and by no means exclusive to humans. There are many situations that can cause stress to an animal: from confinement to small spaces to excessive handling (by people) or isolation from other members of its species. This last factor is key in certain varieties of primates, which live in hierarchical communities.which live in hierarchical communities and may have different levels of stress depending on their place in them (higher among non-dominant males of intermediate degree).
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 may harm themselves when caged or isolated from the environment (in socially poor spaces). Common self-harming actions involve scratching and biting on different parts of the body, as well as plumage plucking in birds.
Animals are susceptible to emotional problemsespecially when they are removed from their natural environment (in zoos, circuses, etc.). Research on this issue is currently increasing, and it is expected to become an area of profound scientific interest in the future.
- Bielecka, K and Marcinów, M. (2017). Mental Misrepresentation in Non-human Psychopathology. Biosemiotics, 10, 195-210.
- Laborda, M., Míguez, G., Polack, C.W. and Miller, R.R. (2012). Animal models of psychopathology: Historical models and the Pavlovian contribution. Terapia Psicológica, 30(1), 45-49.
(Updated at Mar 28 / 2023)