treatment should begin with an identification of the underlying cause. Pain-induced stress should then be alleviated by removal of the cause of the pain or through administration of analgesics, but non-pain-induced stress is seldom amenable to pharmacologic treatment alone. Rather, environmental stressors or factors should be addressed. The use of tranquilizers can sometimes help an animal adapt to necessary changes in its environment, but is seldom sufficient in itself.

This report places considerable emphasis on the importance of recognizing maladaptive behaviors resulting from stress with which an animal is unable to cope effectively as evidence of distress. Some conditions of acute stress in which an animal's behavior is normal and adaptive also suggest that intervention is warranted. Such conditions are brought on typically when an animal is strongly motivated to avoid or escape a stimulus or set of conditions. Such behaviors, like maladaptive ones, should be interpreted as causing harm to the animal and producing unwanted variability in research data.

The tranquilizers and sedatives used in animals today include drugs in four groups: phenothiazines, butyrophenones, benzodiazepines, and α2-Adrenergic agonists. Phenothiazines and butyrophenones have many common properties, especially general sympatholytic activity. They used to be considered "major" tranquilizers in human medicine; currently preferred terms are antipsychotics and neuroleptics. Benzodiazepines, once considered "minor" tranquilizers, are now thought of as antianxiety-sedative agents. α2-Adrenergic agonists have emerged as a very important group of drugs for tranquilizing and sedating animals.

Promazine (Sparine®) and acetylpromazine (Acepromazine®).

Phenothiazines depress many physiologic functions, decrease motor activity, produce mental calming, and increase the threshold of response to environmental stimulation. Thus, they are useful for animal restraint. They do not produce sleep, analgesia, or anesthesia. The sedation produced by phenothiazines differs from the state produced by barbiturates and opioids, in that sedation occurs without hypnosis and the effects produced in animals can be reversed with an adequate stimulus.

In animals, adequate doses produce a quieting effect that includes sedation, ataxia, an increase in the threshold of response to environmental stimuli, relaxation