Can animals get depression?

Can a wild or domestic animal develop depression? Let's see what we know so far.

Can animals develop depression? Extrapolating mental disorders to animals based on human criteria is perhaps not entirely accurate.

However, it has been possible to see behaviors in animals that would coincide with psychopathology that, until now, was diagnosed in humans.

The question is very complex, and we will discuss it below, trying to give a well-documented answer as to whether it is possible for animals to suffer from depressive symptoms.

• Related article, "What is Ethology and what is its object of study?"

Is it possible for an animal to develop depression?

In the same way that humans can present a wide repertoire of psychological problems, which have a negative impact on our well-being, it has been shown that many animals, especially mammals, can also suffer from psychopathology.

However, the study of animal psychopathology the study of animal psychopathology is a very complex issue.However, the study of animal psychopathology is a very complex issue, without being able to say with a resounding "yes" that animals suffer from mental disorders. The reason for this is that the conception of current mental disorders has been made on the basis of what is understood to be an adjusted human being in vital aspects such as family, social relations, work/studies, and so on. These aspects, as will be understood, are not all of them to be found in other species.

Thus, given that depression is understood as a set of human symptoms based on human criteria, how is it possible to diagnose it in humans?how is it possible to diagnose it in other animals? The DSM and ICD criteria can be helpful in trying to give a diagnostic label to an animal, but it can never be overlooked that such a diagnosis would not be exhaustive or entirely accurate for the 'patient' to whom it has been given.

Taking all this into account, in the following sections we will try to give a better explained answer as to why animals can have depression, but always bearing in mind that the way depressive symptomatology is seen in non-human animals should be considered provisional.

Animals and humans: can they be compared?

Humans have a wide repertoire of behaviors. Some of them are healthy, providing us with well-being and a correct social adjustment, while others are detrimental, bringing us all kinds of psychological problems, or are caused by a psychological problem behind them.

Trying to see whether or not animals have mental disorders and, in particular, depression, is something really complicated, since the researcher who carries out the study that addresses this issue will not be able to dissociate himself from his human conception of psychopathology. Interpreting depression in animals will always be done, whether one wants to or not, from a human perspective..

Despite the difficulty of extrapolating human mental disorders to animals, it is curious how most of the research on psychopathology has been done using animal models. The idea behind this type of research, which usually takes an evolutionary view, is that the brain mechanisms seen in humans are also shared in other species. This would mean that neurological problems in animals could be replicated in humans.

It is difficult to believe that animals can have depression but, ironically, many Antidepressant drugs have been tested in animals, showing how brain structures homologous to ours function in the absence or presence of neurotransmitters such as dopamine and serotonin, which are implicated in depression.

Many neurologists and neurosurgeons, such as Philip R. Weinstein, maintain that many brain structures are shared by several vertebrate species, especially among mammals. These structures perform, in the vast majority of cases, similar functions. Among them, the brains of several primate species, such as chimpanzees, are particularly noteworthy.

The case of animals in captivity

When it comes to studying depression in other species, the most studied have been animals that have been bred in captivity, especially in places where they have had reduced space, have suffered mistreatment and have not been able to perform a behavior typical of their species in the wild.

The debate on animal experimentation is as hot a topic as that of the existence of zoos and circuses.. Researchers, for better or worse, have at their disposal animals with which they can carry out situations such as sensory deprivation, forced separation and food limitation. Despite the fact that all animal experimentation is done for a purpose and must pass an ethical committee.

However, one situation where ethics is conspicuous by its absence is in animal shows, especially in circuses and zoos with few scruples. This should not be interpreted as a generalization, since we are not saying that all animal shows abuse animals. Zoos carry out an impeccable task of species conservation in most cases, and many circus companies are releasing their animal-actors.

Unfortunately, many of the animals in such places are mistreated, are subjected to harsh training that involves great physical, psychological and emotional stress.This causes deep wounds in their mental health, which will eventually manifest itself in the form of behavioral problems, depression and anxiety.

However, regardless of whether there is mistreatment or not, what must be understood about these animals is that they are not in their habitat. They do not develop in the same way as animals of the same species would in the wild. This means that, unable to show their true nature, confined to a few square meters, they are forced to reserve their energies, which sooner or later will emerge to the surface in a variety of ways.

Because of this, and especially in very mistreated animals, which end up showing unhealthy end up showing unhealthy behaviors, such as self-injury, pulling out their hair or feathers, scratching until blood comes out.scratching until blood comes out, as well as being apathetic, with acquired helplessness and nervousness.

How to know if an animal is depressed?

When we talk about depression in animals, many people have the preconceived idea that the symptoms associated with this mood disorder will manifest themselves in a more or less similar way in all species. This is not the case. In the same way that animals have different plumage and fur, eat different things and play different roles in the food chain, their depressive behaviors will also vary depending on the species.

However, it has not been possible to study it has not been possible to study all the animal species in the world.However, it has not been possible to study all the animal species in the world, nor is it conceivable that certain species, such as corals or barnacles, could have depression as we understand it behaviorally. Most of the research has focused on mammals, especially chimpanzees and pets such as dogs and cats.

Within the field of primatology, although many apes have shown abilities to learn human language far superior to other animals, it must be said that their linguistic skills are limited. It does not allow them to reveal their inner world, a fundamental aspect in the diagnosis of depression in humans, since it is important to know how they experience their problems.

Most researchers with chimpanzees use observation to learn about their mental health. While observing them, they look at their social behavior, their sexual interest, what their motivation is in front of food, whether they decide to cope with a situation or not.They look at their social behavior, their sexual interest, their motivation in front of food, whether they decide to face a potentially lethal threat, whether they separate from the group, and whether their sleep patterns have been altered without an apparent environmental cause.

An example of depression in chimpanzees is the case of Flint, a chimpanzee who was studied by primatologist Jane Goodall in Tanzania's Gombe National Park and who can be read about in her book Through a window (1990).

Flint lived with her mother until she died. Since then, she began a period of mourning, isolating herself from the rest of the chimpanzees and remaining still, staring into infinity, eating absolutely nothing. She kept looking towards the horizon, hoping that her mother would return. In the meantime, she grew weaker and weaker until she finally died of starvation.

Leaving chimpanzees aside, we move on to pets, especially dogs. Veterinarians often see dogs who display all sorts of behaviors when their owners leave home, showing separation anxiety, crying, howling and behaving in a very impulsive manner.. Self-injury has also been seen, such as scratching until they bleed and hitting the door so violently that they hurt themselves. There are even dogs who, when depressed, start chasing imaginary flies.

As for cats, when they are very depressed they do just the opposite of dogs: they remain still, immobile, afraid to make any movement.

Bibliographic references:

• Brent L, Lee DR, Eichberg JW (1989) The effects of single caging on chimpanzee behavior. Lab Anim Sci 39: pp. 345 - 346.
• Koob GF, Ehlers CL, Kupfers DJ, editors. (1989) Animal models of depression. New York: Springer-Verlag. 300 p.
• Harlow HF, Dodsworth RO, Harlow MK (1965) Total social isolation in monkeys. Proc Natl Acad Sci U S A 54: pp. 90 - 97.