A rabbit grinding its teeth. A novice owner might think it is a sign of contentment (purring). A veterinary behaviorist knows bruxism in rabbits is a classic, late-stage sign of severe abdominal pain. The intersection of ethology (the science of animal behavior) and pathology saved that rabbit’s life.

In human medicine, vital signs are pulse, respiration, temperature, and blood pressure. In veterinary science, a growing consensus argues for a fifth: .

When medical causes are ruled out, primary behavioral disorders are diagnosed. The most prevalent seen in practice include: