Today an animal's psychological constitution is recognised by veterinary surgeons as an important part of its living conditions in domestication or captivity.

A common cause of disordered behaviour in captive or pet animals is lack of stimulation, inappropriate stimulation, or overstimulation, leading to a change in psychological constitution or behaviour when they are not stimulated enough, stimulated in the wrong way, or overstimulated. This can lead to disorders, unpredictable and unwanted behaviour, and sometimes even physical symptoms and diseases. For example rats that are exposed to loud music for a long period will ultimately develop unwanted behaviours that have been compared with human psychosis, like biting their owners.

The way dogs behave when understimulated is widely believed to depend on the breed as well as on the individual animal's character. For example, huskies have been known to completely ruin gardens and houses, if they are not allowed enough activity. Dogs are also prone to psychological damage if they are subjected to violence. If they are treated very badly, they may become dangerous.

The systematic study of disordered animal behaviour draws on research in comparative psychology, including the early work on conditioning and instrumental learning, but also on ethological studies of natural behaviour. However, at least in the case of familiar domestic animals, it also draws on the accumulated experience of those who have worked closely with the animals.