Measurement of rat foot pad swelling in rat adjuvant-induced arthritis (AA) model. Animals were injected at the base of the tail with Mycobacterium butyricum in mineral oil on day 0 to induce disease. On day 10 (arrow), pumps were implanted and foot swelling measured twice a week from day 14 to day 24. CP-690550 decreased hind paw swelling in a dose dependent manner. In the rat AA model, data were expressed as percent control with the diseased vehicle treatment group on day 24 being set to 100%. As early as day 14, both the 5 and 15 mg/kg dose of CP-690550 resulted in a statistically significant decrease in foot volume. By day 17, all doses of CP-690550 resulted in a statistically significant decrease in foot volume that remained significant for the rest of the study. Data are mean ± standard error of the mean of 10 animals per group, except for the naïve group (n = 5).