Rat adjuvant arthritis is an experimental model of polyarthritis.
The hallmarks of this model are reliable onset and progression of robust, easily measureable, polyarticular inflammation, marked bone resorption and periosteal bone proliferation.
Cartilage destruction occurs but is disproportionally mild in comparison to the inflammation and bone destruction that occurs.
The primary endpoints for rat adjuvant arthritis are body weight, paw swelling, splenomegaly, histology for inflammation and bone resorption and splenic changes of inflammation, increased extramedullary hematopoiesis and lymphoid atrophy.
Cartilage damage is not scored in this particular model since it is considered a minor feature and not reliable for evaluation of treatment effects.
The stain most commonly used to evaluate this animal model of disease is Hematoxylin and Eosin.