Rodentia

The order Rodentia is the largest order of mammals, with 2277 species grouped together in part based on the commonality of a single pair of continuously growing upper and lower incisors. For most small rodents, frequently used imaging modalities include radiographs, CT, and US. Magnetic resonance imaging may be used in some cases, but it is typically reserved for larger rodents where the ability to perform adequate patient monitoring and perform longer anesthetics is less of a concern. The thorax of many rodent species is unique and may differ from other species of mammals. The gastrointestinal anatomy of various rodent species varies considerably. Many rodents have a simple gastrointestinal tract with a simple glandular stomach and a monogastric system. In female rodents, the urinary and reproductive tracts terminate in separate urethral and vaginal orifices. Imaging has been noted to play an important role in identifying pregnancies, and radiography is the common imaging modality.