Antigen-induced (Dumonde Glynn) arthritis in the sheep: a large joint animal model of arthritis.

Objective. To determine if the Dumonde Glynn model of arthritis can be established in sheep since a larger model would facilitate injection and the measurement of joints. Methods. Three groups ofsheep were immunised with ovalbumin in Freund's adjuvant. Arthritis was induced in group I (n = 10) by the injection of5 mg ovalbumin in 0.5 ml to the right hock joint. Control groups received saline (n = 10) or no treatment (n = 6). Results. Following joint injection the mean AP diameter increased so that there was a 32% difference between the right and left joints at 24 hr (p < 0.001) declining gradually to 12% (p < 0.01) J9 days after the induction of arthritis. The level of haptoglobin in group 1 prior to the induction of arthritis was 0. 04 ± 0.01. Haemoglobin binding capacity (mg/ml) peaked on day 3 at 0.33 ± 0.13 (p < 0.01), and was 0.110 ± 0.05 thirteen days after joint injection. Features observed included proliferation of the joint lining, fibrin deposition and early erosion of cartilage. Synovial membrane showed an infiltrate of inflammatory cells identified as monocytes/macrophages and lymphocytes. Synovial histology scores were 1.8 ± 0.2 for the left joint and 9.3 ± 0.73 for the arthritic right joint. Conclusion. We conclude that this is a model ofmono-arthritis particularly useful when a larger joint is required for intra-articular injection or repeated joint measurements such as in a clinical trial.