The various reactions of animals to the effect in the situation they are in are an indicator of the psychological state of the animal. These psychological indicators can be determined by the various behaviors, emotional states and welfare levels of animals. They exhibit normal and abnormal behaviors depending on the emotional state of the animal. These behaviors vary depending on genetic, environmental, species, breed, age, psychological and physiological conditions of the animal. In addition, the pet's learning process, shape, encoding, storing, retrieval, etc. closely related to the process. Behaviors exhibited are exhibited outside the normal depending on various environmental factors such as stress. Various abnormal behaviors, especially in cats and dogs, are an indicator of the psychological state of the animal. Aggression behaviors in dogs (status-related attack, intermale attack, predatory attack, idiopathic anger attack, fear-induced attack, territorial attack and instinctive attack ( maternal), environmentally harmful behaviors, caprophagy, social behavior and agonistic behaviors are observed.