Collagen-induced arthritis (CIA) is a condition induced in mice (or rats) to study

rheumatoid arthritis Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and hands are involv ...

. CIA is induced in mice by injecting them with an emulsion of complete Freund's adjuvant and

type II collagen Type II collagen is the basis for hyaline cartilage, including the articular cartilages at joint surfaces. It is formed by homotrimers of collagen, type II, alpha 1 chains. It makes up 50% of all protein in cartilage and 85–90% of collagen of ...

. In rats, only one injection is needed, but mice are normally injected twice. Arthritis in mice induced by a single immunisation with collagen
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References

Animal testing Arthritis Collagens {{disease-stub