Modification to the RITARD surgical model.

The Removable Intestinal Tie-Adult Rabbit Diarrhea (RITARD) procedure is the surgical model of choice for studying pathogenesis of diarrheas of Campylobacter, Escherichia coli, and Aeromonas origin. Other than nonhuman primates, the RITARD rabbit is the only model that closely resembles human infection. Classically, the RITARD model is created by isolating the terminal ileum using umbilical tape placed in a slipknot fashion, and injecting the occluded segment with the organism of choice. The slipknot is removed at 4 h postinoculation and patency of the gut reestablished. We found removal of the umbilical tape to be extremely difficult, usually requiring a second surgery to gently untie the material and prevent destruction of the fragile intestinal tissue. This complication of the described procedure appeared to be related to the absorptive and abrasive nature of the tape material. The modification described uses the same idea, but a different material and a different knot pattern. The tubing was easily removed at the prescribed 4 h postsurgery, without an additional surgery. The tubing did not adhere to or damage the gut, yet did provide the occlusive seal required for a 4-h static gut. Histologically, no evidence of pressure could be found at the tie site.