Surgical and postoperative events during permanent fistulation of sheep rumen by the Schalk and Amadon method

Objective To describe and report on the course of events during and after surgical fistulation of sheep rumen by the Schalk and Amadon method and on improvements to address current trends in animal health, care and welfare. Methods A permanent re-entry fistula was created in 13 sheep using a method in which a fold of rumen is exteriorised and held by a metal clamp. Following surgery, sheep were monitored daily for any abnormalities for 4 weeks, then weekly for 6 months. Results Permanent fistulation was achieved in all 13 sheep; 2 sheep had minor complications: one during the surgery (rumen perforation) and one on the day after surgery (slipping of the metal clamp), but both recovered within 48 h with treatment. Over the 4 weeks post-surgery, 7 sheep had mildly elevated rectal temperatures, which resolved with non-steroidal anti-inflammatory drugs, systemic antibiotics and/or topical antiseptic cream. There was an 8-day variation among sheep in the time from surgery to creation of the fistula. Conclusion Rumen fistulation of sheep by the Schalk and Amadon method, as described here, is a comparatively simple, safe and ethical procedure, with minimal effect on or complications for the animal.