All the high drinking lines continue to drink until they reach a blood alcohol level of approximately 60–70 mg%. While this level is slightly above the 50 mg% criterion for driving under the influence in the USA, it is not sufficient to induce overt intoxication in rodents. Under some conditions (e.g., when alcohol is administered for months, or offered sporadically), some animals can be induced to drink excessive amounts. The effective procedures, however, are arduous (Rodd et al. 2009). The most effective method, and in our view the method with the most face validity, is to combine periods of free access to alcohol with periods where alcohol is forced upon the animals, usually through forced inhalation of alcohol vapor. Alternating these conditions can lead to a substantial increase in preference drinking, which has been proposed to be due to self-medication of an alcohol withdrawal state (Becker and Lopez 2004; Spanagel 2009; O'Dell et al. 2004).
