Behavioural problems in pets can be seen as acquired disorders. They develop due to circumstances such as inappropriate husbandry conditions (ie. conditions that are alien to their species), isolation or deprivation of social interaction. A common example of a situation leading to abnormal behaviour in dogs and cats is that of the owner having to leave the animal alone at home, which might produce separation anxieties and possibly to destructive and/or aggressive reactions. For dogs, another common scenario is that they may have been trained to display aggressive behaviour in order to protect the owners or their property. If handled in an inappropriate way, this kind of behaviour can go out of hands thus leading to dangerous animals.

In order to understand the mechanisms and reasons for canine and feline behaviour to take on undesirable dimensions it is useful to have a look at the evolution and domestication of these species.