Can animals have depression?

Can animals develop depression? Extrapolating mental disorders to animals but based on human criteria is something that may not be 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 are going to deal with it below, trying to give a well-documented answer on whether it is possible for animals to suffer from depressive symptoms.

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Is it possible for an animal to develop depression?

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

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 based on what is understands by being a human being adjusted in vital aspects such as family, social relationships, work/studies, and else. These aspects, as can be understood, are not all of them found in other species.

So, since depression is understood as a set of human symptoms based on criteria, also humanHow is it possible to diagnose it in other animals? The DSM and ICD criteria can be helpful in trying to give an animal a diagnostic label, but never it can be set aside that this 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 are going to try to give a better explained answer about why animals can have depression, but always keeping in mind that the way in which depressive symptomatology is seen in non-human animals should be considered as provisional.

Animals and humans: can they be compared?

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

Trying to see whether or not animals have mental disorders, and especially depression, is really complicated, since the The researcher who carries out the study that addresses this issue will not be able to disassociate himself from his human conception of the psychopathology. Interpreting depression in animals will always be done, like it 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 based on animal models. The idea behind this type of research, which tends to take an evolutionary view, is that the brain mechanisms seen in humans are also shared in other species. This would come to say that neurological problems in animals could be replicated in humans.

It's hard to think that animals could have depression, but ironically, many antidepressant drugs have been tested on animals, seeing how brain structures homologous to ours function in the absence or presence of neurotransmitters such as dopamine and serotonin, involved in the depression.

Many neurologists and neurosurgeons, such as Philip R. Weinstein, argue that many brain structures are shared by various species of vertebrates, especially among mammals. These structures perform, in the vast majority of cases, similar functions. Among them, the brain of various species of primates, such as chimpanzees, is especially noteworthy.

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The case of animals in captivity

When studying depression in other species, the most studied has been animals that have been bred in captivity, especially in places where they have had little space, have suffered mistreatment and have not been able to carry out a behavior typical of their species in a state of wild.

The debate on animal experimentation is as hot a topic as 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 with an objective and must pass an ethical committee

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

Unfortunately, many of the animals in these types of places suffer mistreatment, they are subjected to hard training that entails great physical, psychological and emotional stress, and this causes deep wounds in their mental health, which will end up manifesting in the form of behavior 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 belonging to the same species in the wild. This means that, by not being able to show their true nature, confined to a few square meters, they forced to reserve their energies, which sooner or later will rise to the surface in very varied.

Due to this, and especially in highly mistreated animals, which end up displaying unhealthy behaviors, such as self-harm, pulling out their hair or feathers, 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 in a more or less similar way in all species. This is not like this. In the same way that animals have different plumage and fur, they eat a wide variety of things and perform a different role in the trophic chain, their depressive behaviors will also be variable depending on the species.

However, it has not been possible to study all the animal species in the world, and the idea that certain species, such as corals or barnacles, may have depression as we understand it behaviorally is not conceivable either. Most of the research has focused on mammals, especially chimpanzees, and pets such as dogs and cats.

Within the field of primatology, despite the fact that many apes have shown some abilities to learn human language far superior to that of other animals, it can be said that their linguistic prowess is limited. It does not allow them to reveal their internal world, a fundamental aspect in the diagnosis of depression with people, since it is important to know how they experience their problems.

Most chimpanzee researchers use observation to learn about their mental health. While they observe them, they look at their social behavior, their sexual interest, what is their motivation in front of food, if they decide to face a life-threatening threat, if they become separated from the group, and if their sleep patterns have been disturbed without apparent environmental cause.

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

Flint lived with his mother until she passed away. Since then, she began a period of mourning, isolating herself from the rest of the chimpanzees and remaining still, looking towards infinity, without eating anything at all. He did not stop looking towards the horizon, hoping that his mother would return. Meanwhile, she gradually weakened until, finally, she died from starvation.

Leaving chimpanzees aside, we move on to pets, especially dogs. Veterinarians often see dogs who exhibit all kinds of behaviors when their owners leave home, showing separation anxiety, crying, howling, and behaving very impulsively. Self-harm, such as scratching until bloody and banging on the door so violently that they injure themselves, have also been seen. There are even dogs who, being depressed, start catching 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 cage 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.