Evaluation of a potential stress effect in rat adjuvant arthritis by using a new and efficient plethysmograph

We describe the basis of a new design for a user-friendly and easily reproduced mercury-displacement plethysmograph. This system was validated using the rat adjuvant-induced arthritis model in female Lewis rats. Furthermore, 2 different caging systems were evaluated to ensure that caging did not have an effect on disease progression and severity. These groups were evaluated further under frequent- and infrequent-handling conditions. Housing had less effect on the amount of swelling seen during the disease than did the amount of handling. Frequent handling significantly reduced the degree of paw swelling. Frequently handled, arthritic rats housed 5 rats per cage in the Box B system also lost a biologically significant amount of weight by the end of the study. Therefore, we do not recommend housing more than 4 rats per cage under these conditions.