Aberrant behavior
Many textbooks offer information about normal rat behavior. Understanding normal behavior is critical for the ability to recognize aberrant behavior. Keep in mind that different strains of rats may also show differences in 'normal' behavior. Each strain has its own characteristics. Some strains are bred and selected for specific disorders. Obese Zucker rats, for example, have metabolic symptoms such as insulin resistance and are used in obesity studies. Other strains are selected for their robust health such as the Wistar Hannover strain. This is an albino rat with a long life span and high survival rate, often used in long-term geriatric research (research into diseases of aging), toxicology and cancer studies.
Aberrant behavior in rats may have many causes, ranging from social conflicts within the group to stress, boredom, pain, or an underlying disease, particularly a brain condition such as a pituitary tumor.
The inability to engage in natural behavior may lead to aberrant behavior. Rats housed in groups may display abnormal aggressive behavior. If the social ranking in a group of rats is not yet established, a male animal may repeatedly attack his cage mates in what is known as 'bizarre fighting'. This may eventually lead to serious injury or death of the victim and sometimes even to cannibalism. Weaving is a subtle form of aberrant behavior; a stereotypic activity where the rat, while stationary, gently and continuously sways its head back and forth.
Aberrant behavior can also manifest itself by markedly increased grooming, stereotypic behavior or apathy.
