ABSTRACT
The rat is the most commonly used animal in drug metabolism and disposition studies because it can be easily acquired, is relatively inexpensive, easily housed and handled, and if selected properly has low genetic variability, resulting in a narrower range of response than many other laboratory species. The smaller size of the rat compared with other laboratory species such as the dog and the monkey usually implies the need for a smaller amount of test compound, an important consideration particularly during the early stages of development of the compound. The rat also demonstrates a good survival rate from surgical trauma and, therefore, is frequently used in studies requiring surgical preparations of the animal model. The rat is firmly held by the skin of the neck and back, and is positioned so that the mouth is in line with the esophagus.
