Do animals have mental health problems?

Many scientists believe at least some animals can have problems that are similar to human mental health disorders. We can’t ask them how they feel, so we look for changes in behaviour, body chemistry, and brain activity that match what we see in stressed or unwell humans.

Some companion animals make for clear examples. Some dogs develop separation anxiety: they panic when their humans leave them alone, bark continuously, destroy objects or harm themselves. Others have been known to display behaviour resembling depression after a bereavement, becoming withdrawn, inactive, and losing their appetite. Veterinarians sometimes use anti-anxiety or antidepressant drugs, along with training and changes in the home, to help them.

Wild and captive animals have also been known to show patterns of concern. Zoo primates kept in bare or crowded enclosures may pace in circles, rock back and forth, and/or bite themselves. Captive elephants often sway for hours. Parrots in small cages sometimes pluck out their feathers. These repetitive, seemingly purposeless actions are called stereotypies and are often linked to long-term stress and frustration.

Brain and hormone studies have also suggested continuity with humans. Stressed animals have raised levels of stress hormones such as cortisol and have changes in brain chemicals such as serotonin.

This said, scientists are careful not to simply copy human labels like “depression” or “schizophrenia” onto animals. Instead, the main idea is that animals can suffer mentally, especially in poor environments, and that the evidence supports better housing, social contact, and enrichment to protect their welfare.