Data from the Iowa State University Veterinary Diagnostic Laboratory (ISU-VDL) shows that diagnosis of Mycoplasma hyosynoviae and Mycoplasma hyorhinis-associated arthritis has increased in swine in the Midwest United States. The two pathogens are known causative agents of arthritis in post-weaned pigs.

A report published by Iowa State summarizes disease characteristics of both pathogens and describes procedures to diagnose Mycoplasma-associated arthritis. An accurate diagnosis is critical to establishing effective treatment and prevention measures in affected herds.

Arthritis is defined as inflammation of the intra-articular tissue of one or more joints. It is characterized by an increased volume of intra-articular fluid with specific features that vary depending on the cause. Features that may have diagnostic significance include color, turbidity, hemorrhage, or exudate.

ISU-VDL researchers diagnosed 431 cases of lameness between 2003 and 2010. Overall, 69 percent of the clinical cases had evidence of infectious arthritis. Mycoplasma species accounted for an average of 17 percent of cases over the time period. An increasing frequency in recent years of up to 37 percent was reported in 2010.

Mycoplasma hyorhinis was diagnosed more frequently in animals 10 weeks of age or younger. Conversely, M hyosynoviae was diagnosed more often in animals over 10 weeks of age.