'''Frustration occurs when an anticipated event does not happen or fails to meet the individual’s expectations'''. For example when the owner fails to provide food on demand, or will not let a cat outside, or a person tries to walk away from a cat when it expects a social interaction to continue. Often the aggression is not an isolated behaviour and the cat also displays '''other frustration-related behaviours''', such as excessive vocalisation or [[Indoor Marking - Cat|indoor marking]] in situations where it appears to be thwarted by circumstance. Frustration-related aggression may be made worse if motivation is abnormally increased by illness. For example, in cats that are suffering from polyphagia due to [[Hyperthyroidism|hyperthyroidism]] or [[Diabetes Mellitus|diabetes mellitus]]. There is also usually a history of hand rearing or a pattern of regular reinforcement of demanding behaviour throughout the cat’s life. | '''Frustration occurs when an anticipated event does not happen or fails to meet the individual’s expectations'''. For example when the owner fails to provide food on demand, or will not let a cat outside, or a person tries to walk away from a cat when it expects a social interaction to continue. Often the aggression is not an isolated behaviour and the cat also displays '''other frustration-related behaviours''', such as excessive vocalisation or [[Indoor Marking - Cat|indoor marking]] in situations where it appears to be thwarted by circumstance. Frustration-related aggression may be made worse if motivation is abnormally increased by illness. For example, in cats that are suffering from polyphagia due to [[Hyperthyroidism|hyperthyroidism]] or [[Diabetes Mellitus|diabetes mellitus]]. There is also usually a history of hand rearing or a pattern of regular reinforcement of demanding behaviour throughout the cat’s life. |