Stress is a physiological phenomenon that motivates a cat to flee or attack when threatened by a predator, while increased stress can lead to abnormal cat functioning and behavioural disorders. Stereotypical behaviours and compulsive disorders are among other things a consequence of chronic stress. The thesis describes the course of the stress response. The differences between acute and chronic stress are discussed, causes of chronic stress and its effects are given. It explains what stereotypical behaviours and compulsive disorders are and how they manifest themselves.