In the fractionated radiation-induced proctitis model, disease is induced with several smaller doses of radiation directed to the distal colon. Animals are monitored daily and evaluated for overall health and survival in addition to diarrhea and bloody stool incidence. A major readout in the model is proctitis severity determined via longitudinal video endoscopic assessments over the course of the study. Peak disease in the fractionated model typically occurs around Day 13 to Day 14, with disease persisting through the final evaluation which often includes histopathology.

• Advantages: short model duration, consistent disease incidence, good for screening potential drug candidates, increased clinical relevance with repeated radiation treatments.
• Disadvantages: smaller market than IBD.

• Sprague Dawley Rat, Lewis Rat
• C57Bl/6 Mice

• Percent weight change
• Survival
• Diarrhea and bloody stool Incidence
• Endoscopy: proctitis scoring
• Terminal colon weight and length measurement
• Terminal histopathology and/or IHC analyses

• Tissue protein analyses
• Peripheral lymphoid organ immunophenotyping
• Intestinal lamina propria immunophenotyping
• Custom assays