Can Dogs Have Schizophrenia? Psychosis In Human Vs. Dogs

You may have seen your dog displaying behavior that you can’t explain, such as responding to stimuli you can’t see or acting in ways that serve no apparent purpose. In some cases, if your pets are behaving in a very bizarre manner, you might even wonder if they’re experiencing psychosis. Can dogs have schizophrenia or similar mental illnesses, or are these only found in humans?

The short answer is that schizophrenia most likely can’t affect animals. This severe psychiatric disorder usually involves disruptions of the kinds of complex cognition that may be unique to humans, such as language, self-concept, and volitional control of behavior. Exploring the reasons why non-human animals don’t experience schizophrenia may shed light on what makes our own species distinct. If you’re living with schizophrenia or other mental health challenges, consider reaching out to a therapist for support and guidance.

Can a dog have mental illnesses?

Saying anything definitive about the minds of non-human animals can be difficult since researchers can’t ask them what they’re thinking and feeling. However, various kinds of behavioral disturbances have been observed in numerous non-human species.

A 2017 article in the Journal of Entomology and Zoology Studies notes that many of these conditions in dogs can be modeled as psychiatric disorders and may be treated using some of the same pharmaceuticals used for humans. Examples include the following:

• Repetitive and often self-harming behaviors that may have links with obsessive-compulsive disorder (OCD)
• Conditions much like anxiety disorders, such as separation anxiety or generalized anxiety 
• Lingering reactions to traumatic events, similar to post-traumatic stress disorder (PTSD)

In some cases, veterinarians may diagnose animals with conditions normally found in humans, such as generalized anxiety disorder (GAD). They may be treated with a combination of medication and behavioral interventions, such as increased exercise.

Behavioral disorders in animals may even be treated with some of the same medications used to manage psychiatric symptoms in humans. For example, increasing numbers of people are using antidepressants to help their pets with anxiety.

Can animals have schizophrenia symptoms?

Although many animals may experience emotional and behavioral disruptions that can resemble mental illness, schizophrenia is likely unique to humans. 

It’s not clear how a veterinarian could accurately identify this condition in an animal. Current guidelines from the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) state that a diagnosis of schizophrenia requires several of the following symptoms:

• Delusions: Fixed beliefs that do not correspond to reality, such as a belief that your actions are being controlled by electromagnetic waves broadcast from a hidden machine
• Hallucinations: Sensory perceptions that differ markedly from reality, such as hearing voices telling you to carry out certain actions
• Disorganized speech: Incoherent speech patterns, such as linking concepts based on rhymes between words rather than logical relationships
• Disruption in social relationships or occupational function: An inability to maintain social relationships or navigate roles and responsibilities at work
• Negative symptoms: The loss of functions like emotional expression, motivation to initiate actions, or complex speech

While body language observations suggest that some non-human animals may experience hallucinations, it’s hard to verify this because we can’t interview them about their perceptions. Other characteristic symptoms of schizophrenia could most likely never be confirmed in a non-human animal. For instance, there’s no way to tell if your dog has any beliefs about the world, let alone whether those beliefs are delusional.

Schizophrenia may be inherently unique to humans

Non-human animals may possess some of these capacities in a limited form, like engaging with imagined scenarios. However, researchers generally believe the functions listed above are significantly more developed in humans than other creatures. For instance, while some primates can learn to communicate simple phrases through sign language, current evidence suggests that only humans can use language to express complex thoughts.

Schizophrenia and other psychotic disorders tend to be characterized by the impairment of these kinds of complex functions. As such, finding truly psychotic animals may be impossible. 

The origin of schizophrenia in human evolution

Scientists have found that schizophrenia is likely partly caused by genetic factors, with some estimates suggesting that it’s roughly 79% heritable. Recent research suggests this disorder may have emerged through the same evolutionary pathway separating humans from other great apes.

There’s no single genetic marker for psychosis, but a 2022 study published in Natureidentified 10 genes that sharply increase the risk for schizophrenia. All were found near sections of the human genome known as “human accelerated regions (HARs).”

These portions of the genetic code are normally found in all human populations and differ a great deal from similar genes in our nearest evolutionary relatives, chimpanzees. They’re usually called “human accelerated” because the genetic differences in question seem to have emerged during a period of rapid evolution — they’re believed to have changed faster than any other segment of the human genome.

In other words, schizophrenia might result in large part from mutations in the very genes that make us human. 

The genetic and neurodevelopmental basis of schizophrenia and psychosis

Many of the genes found in HARs tend to be involved in the development of the brain and nervous system. They appear to play a large role in the expansion of the cerebral cortex, particularly the areas that are larger in humans than in other creatures. This may be a key requirement for the development of the highly complex brain structures that enable functions like language processing and abstract thought.

The structures in question have well-established links with schizophrenia. For instance, many studies have found that people with this disorder tend to possess abnormalities in the dorsolateral prefrontal cortex (DLPFC). The DLPFC is usually involved in high-level cognitive control tasks, such as the following:

• Decision-making
• Planning
• Working memory
• Cognitive flexibility (switching between mental tasks or strategies)

This is also considered one of the most “human-specific” areas of the brain, having emerged later in evolution than most other regions. The size and complexity of the DLPFC are greater in primates than in other animals, and the region tends to be disproportionately large in humans, even compared to other apes. Genes found in HARs may play a significant role in the growth of this brain structure.

Schizophrenic risk: Could it be an evolutionary tradeoff?

Researchers investigating these links found evidence that some of the genes that confer risk for schizophrenia may also enrich neurological development. Specifically, they’re often correlated with increased size and connectivity in brain cortex tissue.

This may be why they’ve persisted in the human genome despite the danger they pose. These genetic variants may offer a combination of risk and reward. Having too many of them can predispose a person to schizophrenia, but having too few might limit the size and complexity of the human brain. 

This may explain why dogs don’t get schizophrenia. They didn’t follow the evolutionary pathway that led humans to develop a larger and more interconnected frontal cortex. As a result, they likely haven’t developed the complex cognitive skills we have, but it’s probable they also didn’t develop our vulnerability to schizophrenia.

In addition to shedding light on the origins of schizophrenia, this type of research may help scientists find new ways to treat it. Identifying the particular genes and proteins that differ between healthy people and those with schizophrenia might point to new treatment targets for medication. 

Can dogs help protect against schizophrenia or another mental illness?

Not only are dogs thought to be immune to schizophrenia, but they might also lower humans’ risk of the disease.

A 2019 study found that people who had pet dogs in early childhood usually had a 24% lower chance of developing schizophrenia later in life. If there was a dog in the household at the time they were born, their risk was typically 55% lower. These findings may still need to be replicated by other studies, but if confirmed, they could offer additional clues to how schizophrenia develops and how it can be prevented.

It’s not yet clear exactly how being around dogs could lower your schizophrenia risk. The researchers suggested a few possibilities.

One possible explanation is immune system modification. Exposure to dogs seems to reduce the immune system’s inflammatory response to harmless stimuli, often leading to a lower risk of allergies and asthma. Some researchers believe that reduced inflammation in childhood may also decrease the odds of developing schizophrenia.

Another potential explanation involves changes in the microbiome. Having pets in the household may change the kinds of symbiotic bacteria living in your body, which could also impact schizophrenia risk.

How do you manage schizophrenia symptoms and other mental illnesses?

Although schizophrenia may have a significant neurodevelopmental component, people who have already developed this illness can often experience significant symptom relief. In many cases, this can involve antipsychotic medications, which are typically considered the first-line treatment option for managing symptoms like hallucinations, delusions, and disordered behavior.

Psychotherapy can help by relieving negative symptoms, such as apathy and lack of pleasure or satisfaction, which are often resistant to antipsychotics. 

In some cases, treatments like cognitive-behavioral therapy (CBT) can also assist with positive symptoms like delusions and hallucinations.

Many people with schizophrenia find it difficult to regularly attend in-person therapy due to symptoms that present challenges to social interaction or life circumstances that pose transportation limitations. Internet-enabled therapy can be a convenient alternative that usually eliminates the need to commute to sessions.

Though research is in the early stages, there’s evidence that online mental health care can be an effective treatment for schizophrenia, although individuals experiencing acute psychosis may need to seek in-person care. A study published in 2016 reported significant reductions in both depressive and positive symptoms from a CBT-based treatment delivered over the Internet.