Detection of Mycoplasma hyorhinis and Mycoplasma hyosynoviae in oral fluids and correlation with pig lameness scores

This study was designed to detect Mycoplasma hyorhinis and M. hyosynoviae in oral fluids and determine their correlation with lameness scores in pigs. Thirty-seven nursery and/or finisher herds were included in this study. Oral fluids were collected by pen. Using species specific real-time PCR M. hyorhinis was detected in 97% of sampled herds, whereas 70% were positive for M. hyosynoviae. Lameness scores were determined for all pigs in each pen where oral fluids were collected. Lameness was identified in 3.9% of pigs across all sampled pens. No correlation was observed between lameness in pigs in a pen and detection of M. hyorhinis in oral fluid samples (p > 0.05), whereas a significant correlation was observed between M. hyosynoviae detection in oral fluids and lameness (p < 0.05). A negative correlation was observed between the proportion of lame pigs in the pen and Ct values for M. hyosynoviae in oral fluids (p < 0.05; r = −0.27). An age-related effect was observed with M. hyosynoviae detection in oral fluids, indicating an increased prevalence of the bacterium in finishers compared to nursery pigs. Under the conditions of this study, M. hyorhinis was frequently detected in oral fluids from nursery and finisher pigs regardless of the clinical presentation of lameness, whereas the detection of M. hyosynoviae varied depending on the age of sample pigs. Our results suggest that oral fluids may not be an informative diagnostic sample for M. hyorhinis associated lameness. However, the association of lameness and M. hyosynoviae detection in oral fluids warrants prospective population-based diagnostic studies.