The left knees of twelve mongrel puppies, eight weeks old, were injected, daily for twelve to eighteen weeks with autologous preserved whole blood or blood and aqueous penicillin. The opposite knees served as controls and were either merely penetrated with a needle without injection or given equivalent volumes of saline solution or saline solution and penicillin daily. Seven animals were given five grams of epsilon aminocaproic acid daily to inhibit plasminogen activation.
In the knees injected with blood, findings similar to those found in human hemophilic arthritis were observed including synovial pigmentation and fibrosis, cartilage fibrillation on the tibia, enlargement of the distal femoral epiphyses, changes in shape of the patella, and changes in the configuration of the joint surfaces. Epsilon aminocaproic acid did not influence the joint changes. Articular cartilage was markedly thickened in all joints injected with blood. The significance of this finding is discussed.