Mycoplasma Hyorhinis Swine Arthritis. II. Morphologic Features

Mycoplasma hyorhinis arthritis, induced in young Yorkshire swine, can be considered as a three‐stage process. The first 3 weeks of the disease were characterized by a severe polyserositis and mild synovitis. In the second stage, mononuclear cell infiltration of the synovium and other tissues was apparent. In the final stage, beginning about 3 months after inoculation, lymphocytic aggregates had become nodular, synovial hypertrophy was pronounced, and bone and cartilage destruction by pannus was common. Continued activity was apparent to Day 224.