J. Vet. Sci. 2016; 17(4): 489-496  https://doi.org/10.4142/jvs.2016.17.4.489
Two clinical isolates of Mycoplasma hyosynoviae showed differing pattern of lameness and pathogen detection in experimentally challenged pigs
Jo?o Carlos Gomes-Neto1,2,*, Matthew Raymond1,3, Leslie Bower1, Alejandro Ramirez1, Darin M. Madson1, Erin L. Strait1,4, Everett L. Rosey5, Vicki J. Rapp-Gabrielson5
1Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA
2Food Science and Technology, University of Nebraska Lincoln, Lincoln, NE 68588, USA
3Wisconsin National Primate Research Center, University of Wisconsin, Madison, WI 53703, USA
4Merck Animal Health, De Soto, KS 66018, USA
5Zoetis Inc., Global Biologics Research, Kalamazoo, MI 49007, USA
Correspondence to: João Carlos Gomes-Neto
Tel/Fax: +1-4023142255; E-mail: jgneto84@huskers.unl.edu
Received: December 28, 2015; Revised: February 19, 2016; Accepted: May 12, 2016; Published online: December 30, 2016.
Mycoplasma (M.) hyosynoviae is known to colonize and cause disease in growing-finishing pigs. In this study, two clinical isolates of M. hyosynoviae were compared by inoculating cesarean-derived colostrum-deprived and specific-pathogen-free growing pigs. After intranasal or intravenous inoculation, the proportion and distribution pattern of clinical cases was compared in addition to the severity of lameness. Tonsils were found to be the primary site of colonization, while bacteremia was rarely detected prior to the observation of clinical signs. Regardless of the clinical isolate, route of inoculation, or volume of inocula, histopathological alterations and tissue invasion were detected in multiple joints, indicating an apparent lack of specific joint tropism. Acute disease was primarily observed 7 to 10 days post-inoculation. The variability in the severity of synovial microscopic lesions and pathogen detection in joint cavities suggests that the duration of joint infection may influence the diagnostic accuracy. In summary, these findings demonstrate that diagnosis of M. hyosynoviae-associated arthritis can be influenced by the clinical isolate, and provides a study platform to investigate the colonization and virulence potential of field isolates. This approach can be particularly relevant to auxiliate in surveillance and testing of therapeutic and/or vaccine candidates. 
Keywords: Mycoplasma hyosynoviae, arthritis, lameness, swine

© 2016 The Korean Society of Veterinary Science.