Behavioral medicine is the scientific study of everything animals do, whether the animals are insects, birds, mammals, fish, or humans. The field of animal behavior is concerned with understanding the causes, functions, development, and evolution of behavior. Behavior refers to the actions or reactions of an organism. Behavior is usually in relation to the environment, and is controlled by the endocrine and nervous systems. The complexity of animal behavior is related to the complexity of the animal's nervous system. Generally, animals with complex nervous systems have a greater capacity to learn and thus adjust their behavior.

An animal's behavior is influenced by many factors. Some of these factors include genetics, experience and learning, environment, and physiology. Several studies have shown that behavior can be inherited to some degree. The effect of other kittens in the litter, the amount and type of human handling (-especially true for kittens), and exposure to new objects and experiences can influence a cat's behavior and character. The brain and its neurotransmitters also play a fundamental role in temperament and behavior. Abnormal levels of various hormones play a role in certain forms of aggression and fear. Regulatory functions of the brain decrease with age, which results in an increase in fears and anxieties.

Understanding the nature of behavior problems is essential to developing a rational basis for their treatment. While this section focuses primarily on the abnormal behavior of cats, the extent to which a cat's behavior is abnormal is defined by its deviation from “normal” or by the problem that this behavior poses to its owner.

Last full review/revision July 2011 by Karen L. Overall, MA, VMD, PhD, DACVB, ABS Certified Applied Animal Behaviorist