Why Did My Rabbit Stop Eating? Principles of Radiology and CT Interpretation of the Gastrointestinal Tract in Small Mammals with Dr Lorrie Gaschen

This lecture will cover a systematic approach to interpreting radiographs of small mammals, with a focus on the gastrointestinal tract. Case examples will center on rabbits and guinea pigs. Because small mammals have large volumes of ingesta and many superimposed structures, radiographic evaluation of the GI tract can be challenging. We will review the radiographic and CT anatomy of the stomach, cecum, appendix, and colon, comparing their expected positions on radiographs with schematics and cross-sectional images. CT plays a key role in understanding the location and appearance of these gastrointestinal structures, enabling more accurate radiographic interpretation. Assessment will begin with stomach size and position, including both subjective evaluation and objective measurements. Examples of gastric dilatation–volvulus (GDV) in rabbits and guinea pigs will be provided, with CT correlation. We will also discuss identifying signs of obstructive ileus, noting that the character of gastric contents can help differentiate mechanical obstruction. Obstruction is typically indicated by fluid and gas accumulation in the stomach, along with distended small intestines containing similar material. Trichobezoars are often difficult to detect radiographically, but they tend to have more characteristic appearances on CT. Serial radiography will also be discussed as an option to monitor content and size of the gastrointestinal tract. Cecal distention and content will be reviewed as key indicators of cecal volvulus and impaction, with corresponding radiographic and CT examples. The anatomy and appearance of the rabbit appendix will also be addressed. Appendicitis and sacculitis in rabbits is very difficult with radiography. Computed tomography is the best method to have a detailed assessment of the enlarged, thickened structures and assessment for heterogenous and even emphysematous content contents with necrosis and abscessation of these structures.