Aggressive behaviors in domestic cats (Felis catus) Behavioral issues of cats include: furniture scratching, aggression, anxiety, over-stimulation, exaggerated vocalizations and excreting outside the litter box. Among these, aggression - both passive and active – is the most commonly encountered problem. Aggressive behavior is a complex phenomenon, dependent on both genetic and environmental factors. Among the factors leading to agonistic behavior two categories are distinguished: psychobiological factors (which include biochemical and physiological processes, disposition and mood, emotional reactions, motor actions and vegetative reactions) and environmental factors (such as incorrect socialization, unfriendly surroundings or irresponsible animal owners) . The most widespread type of aggression in cats reared in groups is linked to the desire to gain and maintain their territory. Another type of agonistic behavior is one born out of fear, exhibited by cats in a crisis situation once there is no escape route, and the animal is certain it has to fight to survive. This behavior differs from others in that aggression is here the last resort and not the first response to a disturbing situation. Another source of aggression may be anxiety caused by a sudden change in the environment, the presence of people and other animals. An interesting type of aggression linked to the natural hunting sequence of cats is aggression during play, which especially affects cats during adolescence. While working with an aggressive animal, a caregiver has a range of different mitigating and calming measures at hand, but their proper selection requires experience and cooperation with a veterinarian and a behaviorist).